British Telecommunications 20-F 5 Jun 19 2019 FY Annual report (foreign) Financial data

Document and Entity Information

Document and Entity Information	12 Months Ended
	Mar. 31, 2019shares
Document Information [Line Items]
Document Type	20-F
Amendment Flag	false
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Entity Registrant Name	BRITISH TELECOMMUNICATIONS PLC /ADR
Entity Central Index Key	0000820534
Current Fiscal Year End Date	--03-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding	8,689,755,905

Group income statement

Group income statement - GBP (£) £ in Millions		12 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Statements [Line Items]
Revenue		£ 23,428	£ 23,723	£ 24,062
Operating costs		(20,004)	(20,339)	(20,892)
Operating profit (loss)		3,424	3,384	3,170
Finance expense		(833)	(794)	(842)
Finance income		306	215	232
Net finance expense		(527)	(579)	(610)
Share of post tax profit (loss) of associates and joint ventures		1	(1)	(9)
Profit (loss) before taxation		2,898	2,804	2,551
Taxation		(551)	(620)	(485)
Profit (loss) for the year		2,347	2,184	2,066
Before Specific Items [Member]
Statements [Line Items]
Revenue	[1]	23,459	23,746	24,082
Operating costs		(19,610)	(19,752)	(19,944)
Operating profit (loss)	[1]	3,849	3,994	4,138
Finance expense		(694)	(576)	(632)
Finance income		306	215	232
Net finance expense		(388)	(361)	(400)
Share of post tax profit (loss) of associates and joint ventures		1	(1)	(9)
Profit (loss) before taxation		3,462	3,632	3,729
Taxation		(663)	(707)	(702)
Profit (loss) for the year		2,799	2,925	3,027
Specific Items [Member]
Statements [Line Items]
Revenue	[2]	(31)	(23)	(20)
Operating costs	[2]	(394)	(587)	(948)
Operating profit (loss)	[2]	(425)	(610)	(968)
Finance expense	[2]	(139)	(218)	(210)
Net finance expense	[2]	(139)	(218)	(210)
Profit (loss) before taxation	[2]	(564)	(828)	(1,178)
Taxation	[2]	(112)	(87)	(217)
Profit (loss) for the year	[2]	£ (452)	£ (741)	£ (961)
[1]	Before specific items.
[2]	For a definition of specific items, see page [210]. An analysis of specific items is provided in note 10.

Group statement of comprehensiv

Group statement of comprehensive income £ in Millions	12 Months Ended
	Mar. 31, 2019GBP (£)
Statement Of Comprehensive Income [Abstract]
Profit for the year	£ 2,347
Items that will not be reclassified to the income statement
Remeasurements of the net pension obligation	(2,102)
Tax on pension remeasurements	384
Items that have been or may be reclassified to the income statement
Exchange differences on translation of foreign operations	64
Fair value movements on assets at fair value through other comprehensive income	3
Movements in relation to cash flow hedges:
net fair value gains (losses)	176
recognised in income and expense	(18)
Tax on components of other comprehensive income that have been or may be reclassified	(41)
Other comprehensive income (loss) for the year, net of tax	(1,534)
Total comprehensive income (loss) for the year	£ 813

Group balance sheet

Group balance sheet - GBP (£) £ in Millions	Mar. 31, 2019	Apr. 01, 2018	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Non-current assets
Intangible assets	£ 14,393	£ 14,455	£ 14,455	£ 15,037
Property, plant and equipment	17,835	17,000	17,000	16,498
Derivative financial instruments	1,481		1,312	1,818
Investments	13,519		13,354	11,606
Associates and joint ventures	47		38	31
Trade and other receivables	445	431	317	360
Contract assets	249	198
Deferred tax assets	1,347	1,326	1,326	1,717
Non current assets	49,316	48,114	47,802	47,067
Current assets
Programme rights	310		272	264
Inventories	369		239	227
Trade and other receivables	3,238	3,692	4,029	3,860
Contract assets	1,353	1,417
Assets held for sale	89
Current tax receivable	110		77	73
Derivative financial instruments	111		197	428
Investments	3,486		3,224	1,740
Cash and cash equivalents	1,664	521	521	526
Current assets	10,730	9,639	8,559	7,118
Current liabilities
Loans and other borrowings	3,140	2,298	2,298	2,791
Derivative financial instruments	48		50	34
Trade and other payables	5,827	5,781	7,190	7,476
Contract liabilities	1,225	1,406
Current tax liabilities	15	331	83	197
Provisions	424		603	625
Current liabilities	10,679	10,469	10,224	11,123
Total assets less current liabilities	49,367	47,284	46,137	43,062
Non-current liabilities
Loans and other borrowings	15,837	13,038	13,038	11,105
Derivative financial instruments	892		787	869
Contract liabilities	200	87
Retirement benefit obligations	7,182	6,847	6,847	9,088
Other payables	1,479		1,326	1,298
Deferred tax liabilities	1,407		1,340	1,240
Provisions	582		452	536
Non current liabilities	27,579	23,877	23,790	24,136
Equity
Ordinary shares	2,172	2,172	2,172	2,172
Share premium	8,000		8,000	8,000
Other reserves	1,425		1,241	1,591
Retained earnings	10,191	11,994	10,934	7,163
Total shareholders equity	21,788	23,407	22,347	18,926	£ 21,325
Total equity and Liabilities	£ 49,367	£ 47,284	£ 46,137	£ 43,062

Group statement of changes in e

Group statement of changes in equity - GBP (£) £ in Millions	Total	Issued Capital [Member]	Share Premium [Member]	Other Reserves [Member]	Retained Earnings (Loss) [Member]
Beginning balance at Mar. 31, 2016	£ 21,325	£ 2,172	£ 8,000	£ 1,392	£ 9,761
Statements [Line Items]
Profit for the year	2,066				2,066
Other comprehensive income (loss) – before tax	(1,671)			1,108	(2,779)
Tax on other comprehensive income (loss)	445			29	416
Transferred to the income statement	(938)			(938)
Total comprehensive income (loss) for the year	(98)			199	(297)
Share-based payments	57				57
Tax on share-based payments	(6)				(6)
Dividends to parent company	(2,350)				(2,350)
Other movements	(2)				(2)
Ending balance at Mar. 31, 2017	18,926	2,172	8,000	1,591	7,163
Statements [Line Items]
Profit for the year | Previously reported [Member]	2,184
Profit for the year	2,184				2,184
Other comprehensive income (loss) – before tax	1,615			(545)	2,160
Tax on other comprehensive income (loss) | Restated Member Previously Stated [Member]	(345)			1	(346)
Tax on other comprehensive income (loss)	(262)
Transferred to the income statement | Previously reported [Member]	277
Transferred to the income statement	277			277
Total comprehensive income (loss) for the year | Previously reported [Member]	3,731			(267)	3,998
Total comprehensive income (loss) for the year	3,338
Share-based payments	84				84
Tax on share-based payments	(2)				(2)
Transfer to realised profit				(83)	83
Other movements	1				1
Ending balance (Previously reported [Member]) at Mar. 31, 2018	22,740
Ending balance at Mar. 31, 2018	22,347	2,172	8,000	1,241	10,934
Statements [Line Items]
Equity before pension restatement	22,740	2,172	8,000	1,241	11,327
Pension restatement	(393)				(393)
IFRS opening balance adjustment	1,308				1,308
Tax on IFRS opening balance adjustment	(248)				(248)
Ending balance	23,407	2,172	8,000	1,241	11,994
Profit for the year	2,347				2,347
Other comprehensive income (loss) – before tax	(1,859)			243	(2,102)
Tax on other comprehensive income (loss)	343			(41)	384
Transferred to the income statement	(18)			(18)
Total comprehensive income (loss) for the year	813			184	629
Share-based payments	67				67
Dividends to parent company	(2,500)				(2,500)
Unclaimed Dividend	5				5
Other movements	(4)				(4)
Ending balance at Mar. 31, 2019	£ 21,788	£ 2,172	£ 8,000	£ 1,425	£ 10,191

Group statement of changes in_2

Group statement of changes in equity (Parenthetical) - GBP (£) £ in Millions	Mar. 31, 2019	Apr. 01, 2018	Mar. 31, 2018	Mar. 31, 2017
Statement Of Changes In Equity [Abstract]
Ordinary shares	£ 2,172	£ 2,172	£ 2,172	£ 2,172
Number of ordinary shares	8,689,755,905
Par value per share	£ 0.25

Group cash flow statement

Group cash flow statement - GBP (£) £ in Millions		12 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Cash flow from operating activities
Profit (loss) before taxation		£ 2,898	£ 2,804	£ 2,551
Share of post tax (profit) loss of associates and joint ventures		(1)	1	9
Net finance expense		527	579	610
Operating profit (loss)		3,424	3,384	3,170
Other non-cash charges		(112)	33	20
Loss (profit) on disposal of businesses		5	(1)	(16)
Depreciation and amortisation		3,546	3,514	3,572
Increase in inventories		(138)	(14)	(33)
Decrease (increase) in programme rights		49	(34)	(95)
(Increase) decrease in trade and other receivables	[1]	(59)	(156)	168
Decrease in contract assets	[2]	15
Increase (decrease) increase in trade and other payables		60	(367)	(150)
Decrease in contract liabilities	[2]	(72)
Decrease in other liabilities	[3]	(1,934)	(775)	(307)
(Decrease) increase in provisions		(92)	(203)	401
Cash generated from operations		4,692	5,381	6,730
Income taxes paid		(431)	(473)	(551)
Net cash inflow from operating activities		4,261	4,908	6,179
Cash flow from investing activities
Interest received		23	7	7
Dividends received from associates and joint ventures				2
Acquisition of subsidiaries	[4]		(16)	18
Proceeds on disposal of subsidiaries, associates and joint ventures	[4]	23	2	46
Acquisition of joint ventures		(9)	(9)	(13)
Outflow on non-current amounts owed by ultimate parent company	[5]	(1,508)	(1,677)	(1,571)
Proceeds on disposal of current financial assets	[6]	12,887	11,134	10,834
Purchases of current financial assetsf	[6]	(13,088)	(12,629)	(9,411)
Proceeds on disposal of non-current investments	[7]	1	19
Purchases of non-current asset investments				(22)
Proceeds on disposal of property, plant and equipment		41	21	26
Purchases of property, plant and equipment and software	[6]	(3,678)	(3,362)	(3,145)
Net cash outflow from investing activities		(5,308)	(6,510)	(3,229)
Cash flow from financing activities
Interest paid		(531)	(555)	(629)
Repayment of borrowings	[8]	(1,423)	(1,401)	(1,805)
Proceeds from bank loans and bonds		3,972	3,760	3
Cash flows from derivatives related to net debt		124	(188)	119
Repayment of acquisition facility				(181)
Repayment of EE revolving credit facility				(438)
Net cash inflow (outflow) from financing activities		2,142	1,616	(2,931)
Net increase in cash and cash equivalents		1,095	14	19
Opening cash and cash equivalentsi	[9]	492	509	452
Net increase in cash and cash equivalents		1,095	14	19
Effect of exchange rate changes		5	(31)	38
Closing cash and cash equivalentsi	[9]	£ 1,592	£ 492	£ 509
[1]	Includes a prepayment of £nil (2017/18: £325m 2016/17: £nil) in respect of the acquisition of Spectrum.
[2]	Contract assets and contract liabilities arise following adoption of IFRS 15 on 1 April 2018. See notes 1 and 2 to the consolidated financial statements
[3]	Includes pension deficit payments of £2,024m (2017/18:£872m, 2016/17: £274m).
[4]	Acquisitions and disposals of subsidiaries are shown net of cash acquired or disposed of and in 2017 included £20m true-up of consideration following the audit of the completion balance sheet relating to the acquisition of EE.
[5]	There are non-cash movements in this intra-group loan arrangement which principally relate to the settlement of dividends with the parent company and amounts the ultimate parent company was owed by the parent company which were settled through their loan accounts with British Telecommunications plc. Refer to note 28 for further information.
[6]	Primarily consists of investment in and redemption of amounts held in liquidity funds.
[7]	Relates to sale of fair value through equity investment in 2018/19 and assets held for sale classified within trade and other receivables in 2017/18.
[8]	Repayment of borrowings includes the impact of hedging and repayment of lease liabilities.
[9]	Net of bank overdrafts of £72m (2017/18: £29m, 2016/17: £17m).

Group cash flow statement (Pare

Group cash flow statement (Parenthetical) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Statements [Line Items]
Pension deficit payments	£ 2,024	£ 872	£ 274
Acquisitions and disposals of subsidiaries true-up of consideration			20
Net of bank overdrafts	72	29	17
Spectrum [Member]
Statements [Line Items]
Prepayments in respect of acquisition	£ 0	£ 325	£ 0

Group plc balance sheet

Group plc balance sheet - GBP (£) £ in Millions	Mar. 31, 2019	Mar. 31, 2018
Non-current assets
Intangible assets	£ 14,393	£ 14,455
Property, plant and equipment	17,835	17,000
Derivative financial instruments	1,481	1,312
Associates and joint ventures	47	38
Trade and other receivables	445	317
Contract assets	249
Deferred tax assets	1,347	1,326
Non current assets	49,316	47,802
Current assets
Programme rights	310	272
Inventories	369	239
Trade and other receivables	3,238	4,029
Contract assets	1,353
Current tax receivable	110	77
Derivative financial instruments	111	197
Cash and cash equivalents	1,664	521
Current assets	10,730	8,559
Current liabilities
Loans and other borrowings	3,140	2,298
Derivative financial instruments	48	50
Trade and other payables	5,827	7,190
Contract liabilities	1,225
Provisions	424	603
Current liabilities	10,679	10,224
Total assets less current liabilities	49,367	46,137
Non-current liabilities
Loans and other borrowings	15,837	13,038
Derivative financial instruments	892	787
Contract liabilities	200
Retirement benefit obligations	7,182	6,847
Other payables	1,479	1,326
Deferred tax liabilities	1,407	1,340
Provisions	582	452
Non current liabilities	27,579	23,790
Equity
Ordinary shares	2,172	2,172
Share premium	8,000	8,000
Other reserves	1,425	1,241
Retained earnings	10,191	10,934
Total shareholders equity	21,788	22,347
Total equity and Liabilities	49,367	46,137
British Telecommunications plc [Member]
Non-current assets
Intangible assets	2,076	2,031
Property, plant and equipment	14,842	13,995
Derivative financial instruments	1,481	1,312
Associates and joint ventures	19,192	23,889
Other investments	14,730	14,805
Trade and other receivables	200	134
Contract assets	15
Deferred tax assets	1,172	1,127
Non current assets	53,708	57,293
Current assets
Programme rights	310	272
Inventories	106	72
Trade and other receivables	1,915	2,300
Contract assets	265
Current tax receivable	646	217
Derivative financial instruments	113	201
Other investments	5,293	5,748
Cash and cash equivalents	1,445	288
Current assets	10,093	9,098
Current liabilities
Loans and other borrowings	14,854	18,494
Derivative financial instruments	48	50
Trade and other payables	3,684	4,239
Contract liabilities	797
Provisions	280	428
Current liabilities	19,663	23,211
Total assets less current liabilities	44,138	43,180
Non-current liabilities
Loans and other borrowings	17,613	14,916
Derivative financial instruments	892	787
Contract liabilities	96
Retirement benefit obligations	6,740	6,434
Other payables	1,974	1,888
Deferred tax liabilities	966	918
Provisions	304	291
Non current liabilities	28,585	25,234
Equity
Ordinary shares	2,172	2,172
Share premium	8,000	8,000
Other reserves	824	703
Retained earnings	4,557	7,071
Total shareholders equity	15,553	17,946
Total equity and Liabilities	£ 44,138	£ 43,180

Group plc balance sheet (Parent

Group plc balance sheet (Parenthetical) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statements [Line Items]
Cash	£ 493	£ 439
Dividends to shareholders	2,500
British Telecommunications plc [Member]
Statements [Line Items]
Cash	310	232
Cash equivalents	1,135	56
Dividends received	1,614	£ 2,057
Dividends to shareholders	£ 2,500

Group plc statement of changes

Group plc statement of changes in equity - GBP (£) £ in Millions	Total	Issued Capital [Member]	Share Premium [Member]	Other Reserves [Member]	Retained Earnings (Loss) [Member]	British Telecommunications plc [Member]	British Telecommunications plc [Member]Issued Capital [Member]	British Telecommunications plc [Member]Share Premium [Member]	British Telecommunications plc [Member]Other Reserves [Member]	British Telecommunications plc [Member]Retained Earnings (Loss) [Member]
Beginning balance at Mar. 31, 2016	£ 21,325	£ 2,172	£ 8,000	£ 1,392	£ 9,761
Statements [Line Items]
Profit for the year	2,066				2,066
Share-based payments	57				57
Tax on share-based payments	(6)				(6)
Dividends to parent company	(2,350)				(2,350)	£ (2,350)
Transferred to the income statement	(938)			(938)
Ending balance at Mar. 31, 2017	18,926	2,172	8,000	1,591	7,163	14,507	£ 2,172	£ 8,000	£ 857	£ 3,478
Statements [Line Items]
Profit for the year	2,184				2,184	2,057				2,057
Actuarial gain (loss)						2,142				2,142
Tax on actuarial gain (loss)						(365)				(365)
Share-based payments	84				84	71				71
Tax on share-based payments	(2)				(2)	(1)				(1)
Tax on items taken directly to equity						12			12
Net fair value loss on cash flow hedges						(360)			(360)
Transferred to the income statement	277			277		277			277
Transfer to realised profit				83	(83)				(83)	83
Other						(1)				(1)
Ending balance at Mar. 31, 2018	22,347	2,172	8,000	1,241	10,934	17,946	2,172	8,000	703	7,071
Statements [Line Items]
Equity before pension restatement	22,740	2,172	8,000	1,241	11,327	18,339	2,172	8,000	703	7,464
Pension restatement	(393)				(393)	(393)				(393)
IFRS opening balance adjustment	1,308				1,308	(16)				(16)
Tax on IFRS opening balance adjustment	(248)				(248)	3				3
Ending balance	23,407	2,172	8,000	1,241	11,994	17,933	2,172	8,000	703	7,058
Profit for the year	2,347				2,347	1,614				1,614
Actuarial gain (loss)						(2,055)				(2,055)
Tax on actuarial gain (loss)						377				377
Share-based payments	67				67	57				57
Tax on share-based payments						1				1
Tax on items taken directly to equity						(38)			(38)
Net fair value loss on cash flow hedges						176			176
Dividends to parent company	(2,500)				(2,500)	(2,500)				(2,500)
Transferred to the income statement	(18)			(18)		(17)			(17)
Unclaimed Dividend	5				5	5				5
Ending balance at Mar. 31, 2019	£ 21,788	£ 2,172	£ 8,000	£ 1,425	£ 10,191	£ 15,553	£ 2,172	£ 8,000	£ 824	£ 4,557

Group plc statement of change_2

Group plc statement of changes in equity (Parenthetical) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017	Apr. 01, 2018
Statements [Line Items]
Ordinary shares	£ 2,172	£ 2,172	£ 2,172	£ 2,172
Number of ordinary shares	8,689,755,905
Par value per share	£ 0.25
Total profit for the period including dividend income	£ 2,347	2,184	2,066
Dividends to shareholders	2,500		2,350
British Telecommunications plc [Member]
Statements [Line Items]
Ordinary shares	£ 2,172	£ 2,172
Number of ordinary shares	8,689,755,905	8,689,755,905
Par value per share	£ 0.25	£ 0.25
Total profit for the period including dividend income	£ 1,614	£ 2,057
Dividends to shareholders	£ 2,500		£ 2,350

Basis of preparation

Basis of preparation	12 Months Ended
	Mar. 31, 2019
Basis Of Preparation [Abstract]
Basis of preparation	Preparation a c n These consolidated financial statements have been prepared in accordance with the Companies Act 2006 as applicable to companies using International Financial Reporting Standards (IFRS), Article 4 of the IAS Regulation and International Accounting Standards (IAS) and IFRS and related interpretations, as adopted by the European Union. The consolidated financial statements are also in compliance with IFRS as issued by the International Accounting Standards Board (the IASB) and interpretations as issued by the IFRS Interpretations Committee. The consolidated financial statements are prepared on a going concern basis. These financial statements consolidate British Telecommunications plc, the parent company, and its subsidiaries (together the ‘group’, ‘us’, ‘we’ or ‘our’). T h o i i n a a t e n p p i n a u n u n a a e ea e a u h n d a e a a t en p n e n h u n u o l p a n o p n New and amended accounting standards The following standards have been adopted during the year and have a significant impact on the financial statements. IFRS 15 ‘Revenue from Contracts with Customers’ a IFRS 15 sets out the requirements for recognising revenue and costs from contracts with customers and includes extensive disclosure requirements. It replaced IAS 18 ‘Revenue’ and related interpretations. The standard requires us to apportion revenue earned from contracts to individual promises, or performance obligations, on a relative stand-alone selling price basis, based on a five-step model. Transition We chose to adopt IFRS 15 using the cumulative effect method. Under this transition method: – the standard has been applied only to contracts in progress but not completed as at 1 April 2018 – for contracts that were modified before 1 April 2018, the aggregate effect of all of the modifications that occurred before this date are reflected as at 1 April 2018 – prior year comparatives have not been restated for the effect of IFRS 15 and continue to be reported under IAS 18. Instead our 1 April 2018 opening retained earnings have been adjusted for the full cumulative impact of adopting the standard. Financial Impact In the prior year Annual Report The cumulative increase in retained earnings is mainly due to the acceleration of handset revenues and, to a lesser extent, deferral of costs, notably third party contract acquisition costs primarily associated with post pay contracts. The financial impact of each business area is as follows: – Under our previous accounting policy, mobile handset revenue was recognised based on the amount the customer pays for the handset when it is delivered to the customer. Generally mobile handsets are either provided free or for a small upfront charge. Under IFRS 15, additional revenue is allocated to the mobile handset at the start of the contract. This is calculated with reference to its relative standalone value within the contract, regardless of the contract pricing. For each mobile handset contract, the revenue recognition profile changes with greater day one recognition of revenue for the handset and a corresponding reduction in ongoing mobile service revenue over the contract period. The difference between the mobile handset revenue recognised and the amounts charged to the customer has been recognised as a contract asset. Over time, we expect the contract asset generated to remain at similar levels as old contracts expire and new ones are signed. However, we will see short-term volatility, for example around key handset launches. This primarily impacted Consumer, and to a lesser extent, mobile handset revenues in Enterprise in respect of the legacy EE business division. There is a similar effect in respect of subsidised equipment although this had a less significant impact due to its lower relative standalone value. – Previously, sales commissions and other third party acquisition costs resulting directly from securing contracts with customers were expensed when incurred. Under IFRS 15, these costs are recognised as an asset, and amortised over the period in which the corresponding benefit is received, resulting in earlier profit recognition. The impact is greatest in Consumer in respect of third-party acquisition costs partially associated with post-pay contracts. – The above two impacts are partly offset by the change in accounting for connections revenue. Previously, the group recognised connections revenue upon performance of the connection activity. Under IFRS 15, connections revenue is deferred and recognised on a straight-line basis over the associated line/circuit contractual period. This means that revenue and profits are recognised later. On transition this created a contract liability as revenue and profits are deferred to future periods. Openreach and Enterprise deliver the majority of this service and therefore experienced the majority of the impact. Over time, this liability is expected to remain at similar levels as old contracts expire and new ones are signed. – We will provide for expected lifetime losses on contract assets as required by IFRS 9 as set out below. – The IFRS 15 impact on other areas was not material. This included certain contract fulfilment costs which are recognised as an asset and amortised over the period in which benefit is received and certain expenses that are recognised as a deduction from revenue. The impact of the adoption of IFRS 15 on opening retained earnings at 1 April 2018 is shown in note 2. The following tables show, for the year ended 31 March 2019, the impact had the IFRS 15 standard not been adopted on the financial statement line items affected for the income statement and balance sheet. There was no net impact on the key cash flow captions (net cash flow from operating activities, net cash flow from investing activities or net cash flow from financing activities). Group income statement Year ended 31 March 2019 As reported (IFRS 15) £m Adjustments £m Amounts without adoption of IFRS 15 (IAS 18) £m Revenue 23,428 (252 ) 23,176 Operating costs (20,004 ) 1 (20,003 ) Operating profit 3,424 (251 ) 3,173 Profit before tax 2,898 (251 ) 2,647 Tax (551 ) 48 (503 ) Profit for the year 2,347 (203 ) 2,144 Group balance sheet As at 31 March 2019 As reported (IFRS 15) £m Adjustments £m Amounts without adoption of IFRS 15 (IAS 18) £m Non-current assets Contract assets 249 (249 ) — Trade and other receivables 445 (149 ) 296 Current assets Contract assets 1,353 (1,353 ) — Trade and other receivables 3,238 180 3,418 Current tax receivable 110 296 406 Current liabilities Trade and other payables 5,827 1,313 7,140 Contract liabilities 1,225 (1,225 ) — Total assets less current liabilities 49,367 (1,363 ) 48,004 Non-current liabilities Trade and other payables 1,479 102 1,581 Contract liabilities 200 (200 ) — Equity Retained earnings 10,191 (1,265 ) 8,926 Total equity and non-current liabilities 49,367 (1,363 ) 48,004 Group cash flow statement Disclosures IFRS 15 requires additional disclosures in our Annual Report. To reflect these expanded requirements we have added a dedicated revenue note (note 6). The key disclosure changes are as follows: – we have changed our revenue disclosures to comply with the requirements to disaggregate revenue recognised from contracts with customers into categories that depict how the nature, amount, timing and uncertainty of revenue and associated cash flows are affected by economic factors – we have provided further detail around contract balances and their movements in the year – we have provided an aggregate amount of the transaction price allocated to performance obligations that are unsatisfied as at the end of the reporting period and an explanation of when these are expected to be recognised as revenue. IFRS 9 ‘Financial Instruments’ IFRS 9 sets out requirements for classification, measurement, impairment and de-recognition of financial assets and liabilities, and includes a new hedge accounting model. It replaces IAS 39 ‘Financial Instruments: Recognition and Measurement’. The standard has not had a material impact on our results, with the key impacts set out below. Impairment of financial assets We have revised the methodologies we use to impair financial assets to reflect the forward-looking ‘expected credit loss’ model introduced by IFRS 9, in contrast to the backward-looking ‘incurred credit loss’ model used under IAS 39. As a result we now recognise a loss allowance for all expected credit losses on initial recognition of financial assets, including trade receivables and the contract assets recognised on transition to IFRS 15. Providing for loss allowances on our existing financial assets has not had a material impact on the financial statements. Classification of financial instruments IFRS 9 introduces new categories of financial instrument: fair value through profit and loss, fair value through other comprehensive income, and amortised cost. These replace the IAS 39 categories of fair value through profit and loss, available-for-sale, loans and receivables, and held-to-maturity. We have reclassified our financial instruments based on these new categories. Certain investments in liquidity funds, disclosed in note 21, were classified as available-for-sale under IAS 39 but have been reclassified to amortised cost under IFRS 9, because they are held to collect contractual cash flows. All other financial instruments classified as available-for-sale under IAS 39, including all equity instruments, have been reclassified as fair value through other comprehensive income under IFRS 9. All financial instruments previously classified as loans and receivables and held-to-maturity under IAS 39, including amounts owed by and due to the immediate and ultimate parent company, have been reclassified as amortised cost under IFRS 9. The classification of all instruments classified as fair value through profit and loss under IAS 39 is unchanged under IFRS 9. Reclassification of liquidity fund investments has not had a material impact on the accounting as they are short-term in nature and amortised cost can reasonably be expected to equate to fair value. The reclassifications have not changed the accounting for any other instruments and therefore their carrying amounts are unchanged under IFRS 9. Hedging We have chosen to adopt the IFRS 9 hedge accounting requirements because they enable us to our align hedge accounting more closely with our risk management activities in the future. Adoption of the revised requirements has had no impact on the effectiveness of our existing hedges, however it has been necessary for us to revise hedge documentation to ensure compliance with enhanced IFRS 9 documentation requirements. We have taken the exemption not to restate comparative information for prior periods with respect to classification and measurement requirements, including the move to the expected credit loss model. Consequently, we have not restated prior period comparatives on adoption of IFRS 9. Other standards The following amended standards and interpretations were also effective during the year, however they have not had a significant impact on our consolidated financial statements. - Classification and Measurement of Share-based Payment Transactions (Amendments to IFRS 2) - Applying IFRS 9 Financial Instruments with IFRS 4 Insurance Contracts (Amendments to IFRS 4) - Transfers of investment property (Amendments to IAS 40) - Annual Improvements to IFRS Standards 2014–2016 Cycle – various standards - IFRIC 22 Foreign currency transactions and advance consideration New and amended accounting standards that have been issued but are not yet effective IFRS 16 ‘Leases’ is effective for the accounting period starting 1 April 2019 and will have a material impact on our financial statements. Background IFRS 16 was published in January 2016 and replaces IAS 17 ‘Leases’ and related interpretations. The standard requires lessees to recognise a right-of-use asset and lease liability for all leases meeting the lease definition set out by the standard unless certain exemptions are available. Accounting for lessors is largely unchanged. Transition We will adopt IFRS 16 on a modified retrospective basis. On transition, remaining payments payable under lease arrangements will be discounted using an appropriate incremental borrowing rate and recognised as lease liabilities. Right-of-use assets will be recognised equivalent to the lease liability, adjusted for any pre-existing prepaid lease payments, accrued lease expenses, and related onerous lease and decommissioning provisions. We will recognise the cumulative effect of initially applying the standard as an adjustment to the opening balance of retained earnings at 1 April 2019, i.e. the date of initial application. Results in the 2019/20 financial year will be reported under IFRS 16 and the Annual Report 2020 will be the first Annual Report to include the results on this basis. We have made significant progress in implementing the standard. A cross-functional project team has been engaged in identifying arrangements in scope of IFRS 16, determining appropriate accounting policies and judgements, and implementing a system solution capable of quantifying the impact of the standard and processing accounting entries on a business-as-usual basis. Practical expedients We have elected to make use of the following practical expedients and exemptions available under IFRS 16: - low-value leases and short-term leases will be excluded from IFRS 16 accounting, i.e. they will be accounted for in the same manner as operating leases currently are - onerous lease provisions in existence at the date of initial adoption will be derecognised and applied against the corresponding right-of-use asset as a proxy for impairment - leases of intangible assets such as software licenses will continue to be accounted for under IAS 38 ‘Intangible Assets’ - where we are lessee in a contract containing both lease components and non-lease components, we will account for the arrangement as though it comprises a single lease component - initial direct costs will be excluded when measuring the right-of-use asset - hindsight will be used when assessing the lease term. BT as lessee All arrangements previously disclosed as operating lease commitments will now be recognised on the balance sheet. A key driver will be group’s portfolio of leased land and buildings, the majority of which is currently recognised off balance sheet following a sale and operating leaseback transaction in 2001. Cell and switch site leases represent another material element, due to the long lease terms associated with these arrangements. On the basis of progress made in implementing the standard, we expect the following impact on adoption: - lease liabilities of between £5.6bn - - the increase in liabilities will have a corresponding impact on net debt and gearing ratios - depreciation expense and interest expense will replace the current operating lease expense, resulting in increased EBITDA - profit after tax will see a reduction in the periods immediately following transition to IFRS 16, driven by interest expense charged in respect of the new leases being ‘frontloaded’ when compared to the previous straight-line operating lease expense - within the cash flow statement, lease payments will now be presented within cash flows from operating activities and cash flows from financing activities in respect of depreciation and interest expense respectively. The timing of cash flows will remain unchanged. BT as lessor Lessor accounting is substantially unchanged under IFRS 16 and we do not expect the standard to have a material impact on the accounting for arrangements currently identified as leases. However, “last mile” arrangements provided by Openreach to communications providers and currently accounted for as service contracts meet the revised IFRS 16 lease definition, with Openreach as lessor. Connection fees received will now be deferred over the lease term, which is longer than the current contractual deferral period as it also covers the duration that we are ‘reasonably certain’ that communications providers will retain the use of the line beyond the contractual period. We have determined that this is 6 months for all last mile arrangements with the exception of FTTP, which is unchanged. Additional deferred income will be recognised in respect of active arrangements at the transition date, with a corresponding adjustment to retained earnings. This is not expected to have a material impact on the balance sheet or income statement. Other standards The following standards and interpretations are applicable in future periods but are not expected to have a significant impact on the consolidated financial statements. - IFRIC 23 Uncertainty over Tax Treatments - IFRS 17 Insurance Contracts Presentation of specific items O u i n a t e n g a n a p a a e d a d n u b e p te m h i e e a i e e a u n d e n d n u n i a p e f n e i d e n o i i o i n T h e n a o en w a h i a a e o i e u b a g e n a n e o e h a n h Executive C o mmitt e e n p d n n a n a u d n l t i n h e a e n a n o e a a n on d u n a w l a i a i a a q e e d a l u e e F u h e e o i o n e a t i a p p p i i o h h e e n t a o n o i e a h na a e o n a u b a e n p o o n Executive Committee . Speci f t o b d e n h f t n a g g n e n t e e u t p t h e Specific items for the current and prior years are disclosed in note 10.

Prior Year Restatement and Open

Prior Year Restatement and Opening Balance Adjustments	12 Months Ended
	Mar. 31, 2019
Prior Year Restatement And Opening Balance Adjustments [Abstract]
Prior year restatement and opening balance adjustments	2. Prior year restatement and opening balance adjustments Revision of segment results During the year we reduced the number of our customer-facing units with a corresponding impact on reportable segments. Our BT Consumer and EE customer-facing units were brought together on 1 April 2018, and our Business and Public Sector and Wholesale and Ventures customer-facing units were combined on 1 October 2018. The group now has four customer-facing units: - Consumer (formerly BT Consumer and EE); - Enterprise (formerly Business and Public Sector and Wholesale and Ventures); - Global Services; and - Openreach. During the year we also transferred our Northern Ireland Networks business from Enterprise to Openreach. Where appropriate, comparative results for all four customer-facing units have been revised to be presented on a consistent basis. This affects the segment information and employees disclosures. See notes 5 and 8 respectively. Restatement of previously issued financial statements for IAS 19 accounting valuation of retirement benefit obligations On 27 July 2018 we announced that we had been alerted to an error made by our independent external actuary in the actuary’s calculation of our IAS 19 accounting valuation of retirement benefit obligations at 31 March 2018. Our independent external actuary is employed as an expert to calculate the IAS 19 accounting valuation on behalf of management. The error resulted from the incorrect application of changes to demographic assumptions. Management determined that the error was material with respect to the statement of comprehensive income and would require us to restate its previously issued consolidated financial statements for the year ended 31 March 2018. The accounting error understated the net pension obligation, after tax, at 31 March 2018 by £393m (£476m gross of deferred tax) and overstated total equity in the balance sheet by £393m. The re-measurement gain of the net pension obligation recorded within the statement of comprehensive income for the year ended 31 March 2018 was overstated by £476m and tax expense on the pension re-measurement was overstated by £83m. The error has no effect on the income statement or the cash flow statement or any amounts included in the financial statements for the year ending 31 March 2017. It also has no effect on the 2017 triennial funding valuation of the BT Pension Scheme, associated cash contributions or on the pension scheme members. Opening balance adjustments resulting from implementation of IFRS 15 and IFRS 9 The transition methods we have chosen in applying IFRS 9 and IFRS 15 means there is no need to restate comparative information for the impact of these standards. We have however adjusted the 1 April 2018 balance sheet to reflect the impact on opening retained earnings of recognition of the IFRS 15 contract asset and liability, and for the IFRS 9 expected loss allowance. Impact of restatement and opening balance adjustments Set out below is the impact of these items on the group statement of comprehensive income and balance sheet. They are already reflected in the group statement of changes in equity as presented on page [XX]. Group statement of comprehensive income Year ended 31 March 2018 (as published) Pension restatement Year ended 31 March 2018 (restated) £m £m £m Profit for the period 2,184 - 2,184 Other comprehensive income (loss) Items that will not be reclassified to the income statement: Remeasurements of the net pension obligation 2,160 (476 ) 1,684 Tax on pension remeasurements (346 ) 83 (263 ) Items that have been or may be reclassified subsequently to the income statement: Exchange differences on translation of foreign operations (188 ) - (188 ) Fair value movements on available-for-sale assets 11 - 11 Movements in relation to cash flow hedges: - net fair value (losses) gains (368 ) - (368 ) - recognised in income and expense 277 - 277 Tax on components of other comprehensive income that have been or may be reclassified 1 - 1 Other comprehensive profit (loss) for the period, net of tax 1,547 (393 ) 1,154 Total comprehensive income (loss) for the period 3,731 (393 ) 3,338 Group balance sheet At 31 March 2018 (as published) Pension restatement At 31 March 2018 (restated) IFRS 9 & 15 opening balance adjustment At 1 April 2018 £m £m £m £m £m Non-current assets Intangible assets 14,455 - 14,455 - 14,455 Property, plant and equipment 17,000 - 17,000 - 17,000 Trade and other receivables 317 - 317 114 431 Contract assets - - - 198 198 Deferred tax assets 1,243 83 1,326 - 1,326 Other non-current assets 14,704 - 14,704 - 14,704 47,719 83 47,802 312 48,114 Current assets - Trade and other receivables 4,029 - 4,029 (337 ) 3,692 Contract assets - - - 1,417 1,417 Cash and cash equivalents 521 - 521 - 521 Other current assets 4,009 - 4,009 - 4,009 8,559 - 8,559 1,080 9,639 Current liabilities Loans and other borrowings 2,298 - 2,298 - 2,298 Trade and other payables 7,190 - 7,190 (1,409 ) 5,781 Contract liabilities - - - 1,406 1,406 Current tax liabilities 83 - 83 248 331 Other current liabilities 653 - 653 - 653 10,224 - 10,224 245 10,469 Total assets less current liabilities 46,054 83 46,137 1,147 47,284 Non-current liabilities Loans and other borrowings 13,038 - 13,038 - 13,038 Contract liabilities - - - 87 87 Retirement benefit obligations 6,371 476 6,847 - 6,847 Other non-current liabilities 3,905 - 3,905 - 3,905 23,314 476 23,790 87 23,877 Equity - Share capital 2,172 - 2,172 - 2,172 All other reserves 9,241 - 9,241 - 9,241 Retained earnings 11,327 (393 ) 10,934 1,060 11,994 Total equity 22,740 (393 ) 22,347 1,060 23,407 46,054 83 46,137 1,147 47,284

Critical accounting estimates a

Critical accounting estimates and key judgements	12 Months Ended
	Mar. 31, 2019
Critical Accounting Estimates And Key Judgements [Abstract]
Critical accounting estimates and key judgements	The preparation of financial statements in conformity with IFRS requires the use of accounting estimates and assumptions. It also requires management to exercise its judgement in the process of applying our accounting policies. We continually evaluate our estimates, assumptions and judgements based on available information and experience. As the use of estimates is inherent in financial reporting, actual results could differ from these estimates. Management has discussed its critical accounting estimates and associated disclosures with the Audit and Risk Committee We have the following critical accounting estimates (E) and key judgements (J): – Current and deferred income tax, see note 11 (E, J). – Goodwill impairment, see note 13 (E, J). – Government grants relating to Broadband Delivery UK (BDUK) contracts, see note 14 (J). – Provisions and contingent liabilities, see note 18 (E, J). – Pension obligations, see note 19 (E, J).

Significant accounting policies

Significant accounting policies that apply to the overall financial statements	12 Months Ended
	Mar. 31, 2019
Significant Accounting Policies [Abstract]
Significant accounting policies that apply to the overall financial statements	The significant accounting policies applied in the preparation of our consolidated financial statements are set out below. Other significant accounting policies applicable to a particular area are disclosed in the most relevant note. We have applied all policies consistently to all the years presented, unless otherwise stated. Basis of consolidation The group financial statements consolidate the financial statements of British Telecommunications plc and its subsidiaries, and include its share of the results of associates and joint ventures using the equity method of accounting. The group recognises its direct rights to (and its share of) jointly held assets, liabilities, revenues and expenses of joint operations under the appropriate headings in the consolidated financial statements. All business combinations are accounted for using the acquisition method regardless of whether equity instruments or other assets are acquired. No material acquisitions were made in the year. A subsidiary is an entity that is controlled by another entity, known as the parent or investor. An investor controls an investee when the investor is exposed, or has rights, to variable returns from its involvement with the investee and has the ability to affect those returns through its power over the investee. Non-controlling interests in the net assets of consolidated subsidiaries, which consist of the amounts of those interests at the date of the original business combination and non-controlling share of changes in equity since the date of the combination, are not material to the group’s financial statements. The results of subsidiaries acquired or disposed of during the year are consolidated from and up to the date of change of control. Where necessary, accounting policies of subsidiaries have been aligned with the policies adopted by the group. All intra-group transactions including any gains or losses, balances, income or expenses are eliminated in full on consolidation. When the group loses control of a subsidiary, the profit or loss on disposal is calculated as the difference between (i) the aggregate of the fair value of the consideration received and the fair value of any retained interest and (ii) the previous carrying amount of the assets (including goodwill), and liabilities of the subsidiary and any non-controlling interests. The profit or loss on disposal is recognised as a specific item. Inventories Network maintenance equipment and equipment to be sold to customers are stated at the lower of cost or net realisable value, taking into account expected revenue from the sale of packages comprising a mobile handset and a subscription. Cost corresponds to purchase or production cost determined by either the first in first out (FIFO) or average cost method. Government grants Government grants are recognised when there is reasonable assurance that the conditions associated with the grants have been complied with and the grants will be received. Grants for the purchase or production of property, plant and equipment are deducted from the cost of the related assets and reduce future depreciation expense accordingly. Grants for the reimbursement of operating expenditure are deducted from the related category of costs in the income statement. Estimates and judgements applied in accounting for government grants received in respect of the BDUK programme and other rural superfast broadband contracts are described in note 14. Once a government grant is recognised, any related deferred income is treated in accordance with IAS 20 ‘Accounting for Government Grants and Disclosure of Government Assistance’. Foreign currencies Foreign currency transactions are translated into the functional currency using the exchange rates prevailing at the date of the transaction. Foreign exchange gains and losses resulting from the settlement of transactions and the translation of monetary assets and liabilities denominated in foreign currencies at period end exchange rates are recognised in the income statement line which most appropriately reflects the nature of the item or transaction. On consolidation, assets and liabilities of foreign undertakings are translated into sterling at year end exchange rates. The results of foreign undertakings are translated into sterling at average rates of exchange for the year (unless this average is not a reasonable approximation of the cumulative effects of the rates prevailing on the transaction dates, in which case income and expenses are translated at the dates of the transactions). Foreign exchange differences arising on the retranslation of foreign undertakings are recognised directly in a separate component of equity, the translation reserve. In the event of the disposal of an undertaking with assets and liabilities denominated in a foreign currency, the cumulative translation difference associated with the undertaking in the translation reserve is charged or credited to the gain or loss on disposal recognised in the income statement. Research and development Research expenditure is recognised in the income statement in the period in which it is incurred. Development expenditure, including the cost of internally developed software, is recognised in the income statement in the period in which it is incurred unless it is probable that economic benefits will flow to the group from the asset being developed, the cost of the asset can be reliably measured and technical feasibility can be demonstrated, in which case it is capitalised as an intangible asset on the balance sheet. Capitalisation ceases when the asset being developed is ready for use. Research and development costs include direct and indirect labour, materials and directly attributable overheads. Leases Under IAS 17, the determination of whether an arrangement is, or contains, a lease is based on the substance of the arrangement and requires an assessment of whether the fulfilment of the arrangement is dependent on the use of a specific asset or assets and whether the arrangement conveys the right to use the asset. Leases of property, plant and equipment where we hold substantially all the risks and rewards of ownership are classified as finance leases. Finance lease assets are capitalised at the commencement of the lease term at the lower of the present value of the minimum lease payments or the fair value of the leased asset. The obligations relating to finance leases, net of finance charges in respect of future periods, are recognised as liabilities. Leases are subsequently measured at amortised cost using the effective interest method. Leases where a significant portion of the risks and rewards are held by the lessor are classified as operating leases. Rentals are charged to the income statement on a straight line basis over the period of the lease. Termination benefits Termination benefits (leaver costs) are payable when employment is terminated before the normal retirement date, or when an employee accepts voluntary redundancy in exchange for these benefits. We recognise termination benefits when they are demonstrably committed to the affected employees leaving the group.

Segment information

Segment information	12 Months Ended
	Mar. 31, 2019
Disclosure Of Operating Segments [Abstract]
Segment information	Significant accounting policies that apply to segment information Operating and reportable segments Our operating segments are reported based on financial information provided to the Executive Committee Our organisational structure reflects the different customer groups to which we provide communications products and services via our customer-facing units: Consumer, Enterprise, Global Services and Openreach. The customer-facing units are supported by an internal service unit, Technology, and corporate units including procurement and property management. The customer-facing units are our reportable segments and generate substantially all of our revenue. Technology and the group’s corporate units are not reportable segments as they did not meet the quantitative thresholds as set out in IFRS 8 ‘Operating Segments’ for any of the years presented. We aggregate the remaining operations and include within the ‘Other’ category to reconcile to the consolidated results of the group. The ‘Other’ category includes unallocated Technology costs and our corporate units. Allocation of certain items to segments Provisions for the settlement of significant legal, commercial and regulatory disputes, which are negotiated at a group level, are initially recorded in the ‘Other’ segment. On resolution of the dispute, the full impact is recognised in the results of the relevant customer-facing unit and offset in the group results through the utilisation of the provision previously charged to the ‘Other’ segment. Settlements which are particularly significant or cover more than one financial year may fall within the definition of specific items as detailed in note 10. The costs incurred by Technology and corporate units are recharged to the customer-facing units to reflect the services it provides to them. Depreciation and amortisation incurred by Technology in relation to the networks and systems it manages and operates on behalf of the customer-facing units is allocated to the customer-facing units based on their respective utilisation. Capital expenditure incurred by Technology for specific projects undertaken on behalf of the customer-facing units is allocated based on the value of the directly attributable expenditure incurred. Where projects are not directly attributable to a particular customer-facing unit, capital expenditure is allocated between them based on the proportion of estimated future economic benefits. Specific items are detailed in note 10 and are not allocated to the reportable segments as this reflects how they are reported to the Executive Committee Measuring segment performance Performance of each reportable segment is measured based on adjusted EBITDA. EBITDA is defined as the group profit or loss before interest, taxation, depreciation and amortisation. Adjusted EBITDA is defined as EBITDA before specific items, net non-interest related finance expense, and share of profits or losses of associates and joint ventures. Adjusted EBITDA is considered to be a useful measure of the operating performance of the customer-facing units because it approximates the underlying operating cash flow by eliminating depreciation and amortisation and also provides a meaningful analysis of trading performance by excluding specific items, which are disclosed separately by virtue of their size, nature or incidence. Revenue recognition Our revenue recognition policy is set out in the following note. Internal revenue and costs Most of our internal trading relates to Openreach and arises on rentals, and any associated connection or migration charges, of the UK access lines and other network products to the customer-facing units, including the use of BT Ireland’s network. This occurs both directly, and also indirectly, through Technology which is included within the ‘Other’ segment. Enterprise internal revenue arises from Consumer for mobile Ethernet access and Technology for transmission planning services. Internal revenue arising in Consumer relates primarily to employee broadband and wi-fi services. Intra-group revenue generated from the sale of regulated products and services is based on market price. Intra-group revenue from the sale of other products and services is agreed between the relevant customer-facing units and therefore the profitability of customer-facing units may be impacted by transfer pricing levels. Geographic segmentation The UK is our country of domicile and we generate the majority of our revenue from external customers in the UK. The geographic analysis of revenue is based on the country of origin in which the customer is invoiced. The geographic analysis of non-current assets, which exclude derivative financial instruments, investments and deferred tax assets, is based on the location of the assets. S e e e e a i As explained in note 2, our reportable segments changed during the year as a result of a reduction in the number of our customer-facing units. The BT Consumer and EE segments disclosed in last year’s accounts have been combined into a single reportable segment named ‘Consumer’, and the Business and Public Sector and Wholesale and Ventures segments now form a single reportable segment, ‘Enterprise’. We also transferred our Northern Ireland Networks business from Enterprise to Openreach and reclassified certain internal revenues generated by our Ventures businesses as segmental revenue rather than as an internal recovery of cost. The prior year comparatives presented in this note have been restated to reflect these changes. Year ended 31 March 2019 (IFRS 15) Consumer £m Enterprise £m Global Services £m Openreach £m Other £m Total £m Segment revenue 10,695 6,292 4,735 5,075 3 26,800 Internal revenue (107 ) (359 ) – (2,875 ) – (3,341 ) Revenue from external customers a 10,588 5,933 4,735 2,200 3 23,459 Adjusted EBITDA b 2,534 1,990 505 2,423 (57 ) 7,395 Depreciation and amortisation a (1,024 ) (634 ) (370 ) (1,468 ) (50 ) (3,546 ) Operating profit (loss) a 1,510 1,356 135 955 (107 ) 3,849 Specific items (note 10) (425 ) Operating profit 3,424 Net finance expense c (527 ) Share of post tax profit (loss) of associates and joint ventures 1 Profit before tax 2,898 Year ended 31 March 2018 (restated) (IAS 18) Consumer £m Enterprise d £m Global Services £m Openreach d £m Other £m Total £m Segment revenue 10,360 6,647 5,013 5,278 8 27,306 Internal revenue (103 ) (441 ) – (3,016 ) – (3,560 ) Revenue from external customers a 10,257 6,206 5,013 2,262 8 23,746 Adjusted EBITDA b 2,376 2,077 434 2,615 6 7,508 Depreciation and amortisation a (992 ) (635 ) (424 ) (1,401 ) (62 ) (3,514 ) Operating profit (loss) a 1,384 1,442 10 1,214 (56 ) 3,994 Specific items (note 10) (610 ) Operating profit 3,384 Net finance expense c (579 ) Share of post tax profit (loss) of associates and joint ventures (1 ) Profit before tax 2,804 Year ended 31 March 2017 (restated) (IAS 18) Consumer £m Enterprise d £m Global Services £m Openreach d £m Other £m Total £m Segment revenue 10,024 6,975 5,479 5,250 10 27,738 Internal revenue (100 ) (480 ) – (3,076 ) – (3,656 ) Revenue from external customers a 9,924 6,495 5,479 2,174 10 24,082 Adjusted EBITDA b 2,168 2,261 495 2,734 (10 ) 7,648 Depreciation and amortisation a (989 ) (613 ) (439 ) (1,414 ) (55 ) (3,510 ) Operating profit (loss) a 1,179 1,648 56 1,320 (65 ) 4,138 Specific items (note 10) (968 ) Operating profit 3,170 Net finance expense c (610 ) Share of post tax profit (loss) of associates and joint ventures (9 ) Profit before tax 2,551 a Before specific items. b c Net finance expense includes specific item expense of £ 139 m (2017/18: £218m, 2016/17: £210m). See note 10. d On 1 October 2018 we transferred our Northern Ireland Networks business from Enterprise to Openreach which resulted in an increase in segment revenue, Adjusted EBITDA and Operating profit in Openreach of £155m, £95m, and £54m and a decrease in segment revenue, Adjusted EBITDA and Operating profit in Enterprise of £117m, £95m, and £54m for the year ended 31 March 2018 and an increase in segment revenue, Adjusted EBITDA and Operating profit in Openreach of £152m, £101m, and £56m and a decrease in segment revenue, Adjusted EBITDA and Operating profit in Enterprise of £112m, £101m, and £56m for the year ended 31 March 2017. Additionally, within the Enterprise segment, we reclassified £224m and £242m of internal revenue generated by our Ventures businesses as segmental revenue rather than as an internal recovery of cost for the years ended 31 March 2018 and 2017, respectively. Internal revenue and costs Internal cost recorded by Year ended 31 March 2019 Consumer £m Enterprise £m Global Services £m Openreach £m Other £m Total £m Internal revenue recorded by Consumer – 69 20 – 18 107 Enterprise 63 – 51 177 68 359 Global Services – – – – – – Openreach 920 401 112 – 1,442 2,875 Total 983 470 183 177 1,528 3,341 Internal cost recorded by Year ended 31 March 2018 Consumer £m Enterprise £m Global Services £m Openreach £m Other £m Total £m Internal revenue recorded by Consumer – 65 20 – 18 103 Enterprise a 130 – 51 173 87 441 Global Services – – – – – – Openreach a 896 480 125 – 1,515 3,016 Total 1,026 545 196 173 1,620 3,560 Internal cost recorded by Year ended 31 March 2017 Consumer £m Enterprise £m Global Services £m Openreach £m Other £m Total £m Internal revenue recorded by Consumer – 62 20 – 18 100 Enterprise a 148 – 71 165 96 480 Global Services – – – – – – Openreach a 910 536 158 – 1,472 3,076 Total 1,058 598 249 165 1,586 3,656 a On 1 October 2018 we transferred our Northern Ireland Networks business from Enterprise to Openreach and we reclassified certain internal revenues generated by our Ventures businesses as segmental revenue rather than an internal recovery of cost. This increases internal revenue recorded by Enterprise by £224m in the year ended 31 March 2018 and £242m in the year ended 31 March 2017. Internal revenue for Openreach has increased by £38m in the year ended 31 March 2018 and £40m in the year ended 31 March 2017. Capital expenditure Year ended 31 March 2019 Consumer £m Enterprise £m Global Services £m Openreach £m Other £m Total £m Intangible assets a 276 180 93 82 49 680 Property, plant and equipment b 718 321 152 1,999 93 3,283 Capital expenditure 994 501 245 2,081 142 3,963 Acquisition of spectrum a – – – – 304 304 Capital expenditure including spectrum 994 501 245 2,081 446 4,267 Year ended 31 March 2018 (restated) Consumer £m Enterprise £m Global Services £m Openreach £m Other £m Total £m Intangible assets a 236 180 92 70 64 642 Property, plant and equipment b,c 683 312 186 1,629 70 2,880 Capital expenditure 919 492 278 1,699 134 3,522 Year ended 31 March 2017 (restated) Consumer £m Enterprise £m Global Services £m Openreach £m Other £m Total £m Intangible assets a 225 141 126 74 55 621 Property, plant and equipment b,c 628 313 235 1,546 111 2,833 Capital expenditure 853 454 361 1,620 166 3,454 a Additions to intangible assets as presented in note 13. b Additions to property, plant and equipment as presented in note 14, inclusive of movement on engineering stores. c On 1 October 2018 we transferred our Northern Ireland Networks business from Enterprise to Openreach. This decreased property, plant and equipment in Enterprise and increased property, plant and equipment in Openreach by £41m and £47m in the years ended 31 March 2018 and 31 March 2017 respectively. Geographic segmentation Revenue from external customers Year ended 31 March 2019 £m 2018 £m 2017 £m UK 19,683 19,687 19,421 Europe, Middle East and Africa, excluding the UK 2,280 2,489 2,841 Americas 936 996 1,148 Asia Pacific 560 574 672 Revenue a 23,459 23,746 24,082 a Before specific items. Non-current assets At 31 March 2019 £m 2018 £m 2017 £m UK 30,057 28,843 28,818 Europe, Middle East and Africa, excluding the UK 2,217 2,527 2,535 Americas 336 331 424 Asia Pacific 110 109 149 Non-current assets a 32,720 31,810 31,926 a

Revenue

Revenue	12 Months Ended
	Mar. 31, 2019
Revenue From Contracts With Customers [Abstract]
Revenue	6. Revenue We adopted IFRS 15 on 1 April 2018. The impact of initial application of the standard is described in notes 1 and 2. Significant accounting policies that apply to revenue On inception of the contract we identify a “performance obligation” for each of the distinct goods or services we have promised to provide to the customer. The consideration specified in the contract with the customer is allocated to each performance obligation identified based on their relative standalone selling prices, and is recognised as revenue as they are satisfied. The table below summarises the performance obligations we have identified for our major service lines and provides information on the timing of when they are satisfied and the related revenue recognition policy. Also detailed in this note is revenue expected to be recognised in future periods for contracts in place at 31 March 2019 that contain unsatisfied performance obligations. Service line Performance obligations Revenue recognition policy ICT and managed networks Provision of networked IT services, managed network services, and arrangements to design and build software solutions. Performance obligations are identified for each distinct service or deliverable for which the customer has contracted, and are considered to be satisfied over the time period that we deliver these services or deliverables. Commitments to provide hardware to customers that are distinct from the other promises are considered to be satisfied at the point in time that control passes to the customer. Revenue for services is recognised over time using a measure of progress that appropriately reflects the pattern by which the performance obligation is satisfied. For time and material contracts, revenue is recognised as the service is received by the customer. Where performance obligations exist for the provision of hardware, revenue is recognised at the point in time that the customer obtains control of the promised asset. long-term fixed price contracts revenue recognition will typically be based on the achievement of contract milestones and customer acceptance. Fixed access subscriptions Provision of broadband, TV and fixed telephony services including local, national and international calls, connections, line rental, and calling features. Performance obligations exist for each ongoing service provided to the customer and are satisfied over the period that the services are provided. Installation services are recognised as distinct performance obligations if their relationship with the other services in the contract is purely functional. These are satisfied when the customer benefits from the service. Connection services are not distinct performance obligations and are therefore combined with the associated service performance obligation. Fixed subscription charges are recognised as revenue on a straight line basis over the period that the services are provided. Upfront charges for non-distinct connection and installation services are deferred as contract liabilities and are recognised as revenue over the same period. Variable charges such as call charges are recognised when the related services are delivered. Where installation activities are distinct performance obligations, revenue is recognised at the point in time that the installation is completed. Mobile subscriptions Provision of mobile postpaid and prepaid services, including voice minutes, SMS, and data services. Performance obligations exist for each ongoing service provided to the customer and are satisfied over the period that the services are provided. Subscription fees, consisting primarily of monthly charges for access to broadband and other internet access or voice and data services, are recognised as the service is provided. One-off services such as calls outside of plan and excess data usage are recognised when the service is used. Equipment and other services Provision of equipment and other services, including mobile phone handsets and hardware such as set top boxes and broadband routers provided as part of customer contracts. Performance obligations are satisfied at the point in time that control passes to the customer. For other services, performance obligations are identified based on the distinct goods and services we have committed to provide. Revenue from equipment sales is recognised at the point in time that control passes to the customer. Where payment is not received in full at the time of the sale, such as with equipment provided as part of mobile and fixed access subscriptions, contract assets are recognised for the amount due from the customer that will be recovered over the contract period. Revenue to be recognised is We recognise revenue based on the relative standalone selling price of each performance obligation. Determining the standalone selling price often requires judgement and may be derived from regulated prices, list prices, a cost-plus derived price, or the price of similar products when sold on a standalone basis by BT or a competitor. In some cases it may be appropriate to use the contract price when this represents a bespoke price that would be the same for a similar customer in a similar circumstance. The fixed element of fixed access and mobile subscription arrangements sold by our Consumer business is typically payable in advance, with any variable or one-off charges billed in arrears. Payment is received immediately for direct sales of equipment to customers. Where equipment is provided to customers under mobile and fixed access subscription arrangements, payment for the equipment is received over the course of the contract term. For sales by our enterprise businesses, invoices are issued in line with contractual terms. Payments received in advance are recognised as contract liabilities, amounts billed in arrears are recognised as contract assets. We do not have any material obligations in respect of returns, refunds or warranties. Where we act as an agent in a transaction, we recognise commission net of directly attributable costs. Where the actual and estimated costs to completion of the contract exceed the estimated revenue, a loss is recognised immediately. We exercise judgement in assessing whether the initial set-up, transition and transformation phases of long-term contracts are distinct from the other services to be delivered under the contract and therefore represent distinct performance obligations. This determines whether revenue is recognised in the early stages of the contract, or deferred until delivery of the other services promised in the contract begins. We recognise immediately the entire estimated loss for a contract when we have evidence that the contract is unprofitable. If these estimates indicate that any contract will be less profitable than previously forecast, contract assets may have to be written down to the extent they are no longer considered to be fully recoverable. We perform ongoing profitability reviews of our contracts in order to determine whether the latest estimates are appropriate. Key factors reviewed include: - Transaction volumes or other inputs affecting future revenues which can vary depending on customer requirements, plans, market position and other factors such as general economic conditions. - Our ability to achieve key contract milestones connected with the transition, development, transformation and deployment phases for customer contracts. - The status of commercial relations with customers and the implications for future revenue and cost projections. - Our estimates of future staff and third-party costs and the degree to which cost savings and efficiencies are deliverable. Disaggregation of revenue from contracts with customers The following table disaggregates revenue from contracts with customers by our major service lines and by reportable segment. The prior year comparatives have been presented consistent with the presentation in last year’s Annual Report under IAS 18. Consumer Enterprise Global Services Openreach Other Total Year ended 31 March 2019 (IFRS 15) £m £m £m £m £m £m ICT and managed networks – 2,236 2,613 – – 4,849 Fixed access subscriptions 4,564 2,181 362 2,135 – 9,242 Mobile subscriptions 3,866 1,277 130 – – 5,273 Equipment and other services 2,158 239 1,630 65 3 4,095 Revenue 10,588 5,933 4,735 2,200 3 23,459 Specific items (note 10) (31 ) Revenue 23,428 2018 2017 Year ended 31 March (IAS 18) £m £m ICT and managed networks 5,530 5,927 Broadband and TV 4,655 4,477 Mobile 6,451 6,358 Calls, lines and connections 5,126 5,069 Transit 265 404 Other products and services 1,719 1,847 Revenue before specific items 23,746 24,082 Specific items (note 10) (23 ) (20 ) Revenue 23,723 24,062 Revenue expected to be recognised in future periods for performance obligations that are not complete (or are partially complete) as at 31 March 2019 is £14,296m. Of this, £9,425m relates to ICT and managed services contracts and equipment and other services which will substantially be recognised as revenue within five years. Fixed access and mobile subscription services typically have shorter contract periods and so £4,871m will substantially be recognised as revenue within two years. Revenue recognised this year relating to performance obligations that were satisfied, or partially satisfied, in previous years was not material. Contract assets and liabilities Significant accounting policies that apply to contract assets and liabilities We recognise contract assets for goods and services for which control has transferred to the customer before consideration is due. These assets mainly relate to mobile handsets provided upfront but paid for over the course of a contract. Contract assets are reclassified as receivables when the right to payment becomes unconditional and we have billed the customer. Contract liabilities are recognised when we have received advance payment for goods and services that we have not transferred to the customer. These primarily relate to fees received for connection and installation services that are not distinct performance obligations. Where the initial set-up, transition or transformation phase of a long-term contract is considered to be a distinct performance obligation we recognise a contract asset for any work performed but not billed. Conversely a contract liability is recognised where these activities are not distinct performance obligations and we receive upfront consideration. In this case eligible costs associated with delivering these services are capitalised as fulfilment costs, see note 16. We provide for expected lifetime losses on contract assets following the policy set out in note 16. Contract assets and liabilities recognised at 31 March 2019 are as follows: 31 March 2019 £m 1 April 2018 £m Contract assets Current 1,353 1,417 Non-current 249 198 1,602 1,615 Contract liabilities Current 1,225 1,406 Non-current 200 87 1,425 1,493 £1,216m of the contract liability recognised at 1 April 2018 was recognised as revenue during the year. Impairment losses of £36m were recognised on contract assets during the year. Other than business-as-usual movements there were no significant changes in contract asset and liability balances during the year.

Operating Costs

Operating Costs	12 Months Ended
	Mar. 31, 2019
Operating Costs [Abstract]
Operating costs	Year ended 31 March Notes 2019 £m 2018 £m 2017 £m Operating costs by nature Staff costs: Wages and salaries 4,258 4,223 4,128 Social security costs 440 461 477 Other pension costs 19 611 624 521 Share-based payment expense 20 67 84 57 Total staff costs 5,376 5,392 5,183 Own work capitalised (834 ) (798 ) (813 ) Net staff costs 4,542 4,594 4,370 Net indirect labour costs a 267 315 399 Net labour costs 4,809 4,909 4,769 Product costs and sales commission b 4,464 4,429 4,588 Payments to telecommunications operators 2,059 2,306 2,653 Property and energy costs 1,325 1,285 1,202 Network operating and IT costs 1,026 963 983 TV programme rights charges 841 763 714 Provision and installation b 624 657 669 Marketing and sales b 322 317 365 Other operating costs b 832 831 676 Other operating income (238 ) (222 ) (185 ) Depreciation of property, plant and equipment Owned assets 14 2,390 2,381 2,382 Held under finance leases 14 2 10 10 Amortisation of intangible assets c 13 1,154 1,123 1,118 Total operating costs before specific items 19,610 19,752 19,944 Specific items 10 394 587 948 Total operating costs 20,004 20,339 20,892 Operating costs before specific items include the following: Leaver costs d 17 50 86 Research and development expenditure e 643 632 638 Operating lease charges 801 732 692 Foreign currency gains (11 ) – (12 ) Inventories recognised as an expense 2,388 2,588 2,680 Government grants (3 ) (3 ) (5 ) a b Included within ‘other operating costs’ in prior years were costs relating to product costs and commissions; provision and installation; and marketing and sales. These are now presented separately. The ‘other operating costs’ in comparative for 2017/18 and 2016/17 has been re-presented for consistency. c Excludes £nil (2017/18: £nil, 2016/17: £62m) of amortisation presented as specific items which relate to a write off of software costs as a result of the integration of EE. d Leaver costs are included within wages and salaries, except for leaver costs of £257m (2017/18: £168m, 2016/17: £37m) associated with restructuring and EE integration costs, which have been recorded as specific items. e Research and development expenditure reported in the income statement, includes amortisation of £581m (2017/18: £573m, 2016/17: £577m) in respect of internally developed computer software and operating expenses of £62m (2017/18: £59m, 2016/17: £61m). In addition, the group capitalised software development costs of £472m (2017/18: £450m, 2016/17: £457 Who are our key management personnel and how are they compensated? Key management personnel comprise executive and non-executive directors and members of the BT Group plc Executive Committee Executive Committee . Compensation of key management personnel is shown in the table below: Year ended 31 March 2019 £m 2018 £m 2017 £m Short-term employee benefits 14.9 12.4 10.9 Post employment benefits 1.4 1.4 1.4 Share-based payments 5.2 6.6 5.8 Termination benefits 0.6 2.2 – 22.1 22.6 18.1 Information concerning directors’ remuneration, pension entitlements and long-term incentive plans is shown in note 27.

Employees

Employees	12 Months Ended
	Mar. 31, 2019
Employees [Abstract]
Employees	2019 2018 2017 Number of employees in the group a Year end 000 Average 000 Year end 000 Average 000 Year end 000 Average 000 UK 84.3 83.4 82.2 82.5 82.8 82.2 Non-UK 22.4 23.1 23.6 23.7 23.6 22.8 Total employees 106.7 106.5 105.8 106.2 106.4 105.0 As explained in note 2, we reduced the number of our customer-facing units during the year. BT Consumer and EE have been combined into ‘Consumer’, and Business and Public Sector and Wholesale and Ventures have been combined into ‘Enterprise’. We also transferred c. 700 employees in our Northern Ireland Networks business from Enterprise to Openreach. The prior year comparatives presented in the table below have been restated to reflect these changes. 2019 2018 2017 Number of employees in the group a Year end 000 Average 000 Year end 000 Average 000 Year end 000 Average 000 Consumer 19.7 19.0 18.2 18.0 17.9 16.8 Enterprise b 13.4 13.8 13.2 13.5 13.4 13.2 Global Services 16.6 16.8 16.9 17.3 17.5 17.4 Openreach b 33.2 31.9 31.2 31.1 30.9 31.6 Other 23.8 25.0 26.3 26.3 26.7 26.0 Total employees 106.7 106.5 105.8 106.2 106.4 105.0 a These reflect the full-time equivalent of full and part-time employees. b The 2018 and 2017 comparatives have been restated to reflect the change in segments and the transfer of Nothern Ireland Networks as described above.

Audit, audit related and other

Audit, audit related and other non-audit services	12 Months Ended
	Mar. 31, 2019
Non Audit Fees [Abstract]
Audit, audit related and other non-audit services	i t e t The following fees were paid or are payable to the company’s auditors, KPMG LLP and other firms in the KPMG network, for the year ended 31 March 2019. Figures in the table below for the years ended 31 March 2017 and 2018 are in respect of fees paid to the company’s previous auditors, PricewaterhouseCoopers LLP. Year ended 31 March 2019 £000 2018 £000 2017 £000 Fees payable to the company’s auditors and its associates for: Audit services a,b The audit of the parent company and the consolidated financial statements 8,118 5,372 4,271 The audit of the company’s subsidiaries 6,049 5,866 5,664 14,167 11,238 9,935 Audit related assurance services c 2,236 1,631 1,865 Other non-audit services Taxation compliance services d – - 366 Taxation advisory services e – - 111 All other assurance services f 748 211 200 All other services g 210 592 2,332 958 803 3,009 Total services 17,361 13,672 14,809 a Services in relation to the audit of the parent company and the consolidated financial statements, including fees for reports under section 404 of the Sarbanes-Oxley Act. This also includes fees payable for the statutory audits of the financial statements of subsidiary companies. This excludes amounts for the audit of BT Group Employee Share Ownership Trust and Ilford Trustees (Jersey) Limited amounting to £32,000. b During the year a further £446,000 of fees were payable to PricewaterhouseCoopers LLP in relation to the audit of 2017/18 subsidiary accounts and the audit of our restated IAS19 accounting valuation of retirement benefit obligations, which have not been included in the 2019 balances in the above table. c Services in relation to other statutory filings or engagements that are required by law or regulation to be carried out by an appointed auditor. This includes fees for the review of interim results, the accrued fee for the audit of the group’s regulatory financial statements and reporting associated with the group’s US debt shelf registration. d Services relating to tax returns, tax audits, monitoring and enquiries. e Fees payable for all taxation advisory services not falling within taxation compliance. f All other assurance services include fees payable to KPMG LLP for agreed upon procedures performed on the estimated impact of the new IFRS 15 revenue accounting standard, which took effect from 1 April 2018 for the 2017/18 audit. g Fees payable for all non-audit services not covered above, principally comprising other advisory services. T h n o e a a t e e i n e i C o a n e l o u o e n e o n i b i L i a i g e n e d n t e l o 0 h a e e a L L i a e f h e o h e m o 1.1 2 1 / 7 2.1 e h o o i i Year ended 31 March 2019 £000 2018 £000 2017 £000 Audit of financial statements of associates 1,005 345 251 Audit-related assurance services 53 – – Taxation compliance services – 153 210 Taxation advisory services – 1,074 493 Other non-audit services 62 565 1,168 Total services 1,120 2,137 2,122

Specific items

Specific items	12 Months Ended
	Mar. 31, 2019
Specific Items [Abstract]
Specific items	Significant accounting policies that apply to specific items We separately identify and disclose those items that in management’s judgement need to be disclosed by virtue of their size, nature or incidence (termed ‘specific items’). Specific items are used to derive the adjusted results as presented in the consolidated income statement presented on page [XX]. Adjusted results are consistent with the way that financial performance is measured by management and assists in providing an additional analysis of the reporting trading results of the group. Specific items may not be comparable to similarly titled measures used by other companies. In determining whether an event or transaction is specific, management considers quantitative as well as qualitative factors. Examples of charges or credits meeting the above definition and which have been presented as specific items in the current and/or prior years include acquisitions/disposals of businesses and investments, retrospective regulatory matters, historical insurance or litigation claims, business restructuring programmes, asset impairment charges, property rationalisation programmes, net interest on pensions and the settlement of multiple tax years. In the event that items meet the criteria, which are applied consistently from year to year, they are treated as specific items. Year ended 31 March 2019 £m 2018 £m 2017 £m Revenue Italian business investigation – – 22 Retrospective regulatory matters 31 23 (2 ) 31 23 20 Operating costs EE acquisition warranty claims – 225 – Restructuring charges 386 241 – EE integration costs – 46 215 Property rationalisation costs 36 28 – Pension equalisation costs 26 – – Retrospective regulatory matters (4 ) 26 481 Italian business investigation (55 ) 22 238 Out of period irrecoverable VAT – – 30 Profit (loss) on disposal of businesses 5 (1 ) (16 ) 394 587 948 Operating loss 425 610 968 Net finance expense Interest expense on retirement benefit obligation 139 218 209 Interest on out of period irrecoverable VAT – – 1 139 218 210 Net specific items charge before tax 564 828 1,178 Taxation Tax credit on specific items above (112 ) (87 ) (154 ) Tax credit on re-measurement of deferred tax – – (63 ) (112 ) (87 ) (217 ) Net specific items charge after tax 452 741 961 Restructuring charges During the year we incurred charges of £386m (2017/18: £ 241 These costs reflect projects within our group-wide cost transformation programme and include costs related to the remaining integration of EE and £23m costs to close the BT Pension Scheme and provide transition payments to affected employees. EE integration costs EE integration costs incurred in prior years (2017/18: £46m, 2016/17: £215m) relate to EE related restructuring and leaver costs. In 2016/17, this also included a £62m amortisation charge relating to the write-off of IT assets as we integrated the EE and BT IT infrastructure. In the current year remaining EE integration activities have been combined into the wider restructuring programme. Retrospective regulatory matters We have recognised a net charge of £27m (2017/18: £49m, 2016/17: £479m) in relation to regulatory matters in the year. This reflects the completion of the majority of compensation payments to other communications providers in relation to Ofcom’s March 2017 findings of its investigation into our historical practices on Deemed Consent by Openreach, and new matters arising. Pension equalisation costs During the year we recognised a charge of £26m (2017/18: £nil, 2016/17: £nil) in relation to the high court requirement to equalise pension benefits between men and women due to guaranteed minimum pension (GMP). Property rationalisation costs We have recognised a charge of £36m (2017/18: £28m, 2016/17: £nil) relating to the rationalisation of the group’s property portfolio and a reassessment of lease-end obligations. Italian business investigation During the year we have released £(55)m provisions relating to settlement of various matters in our Italian business (2017/18: a charge of £22m, 2016/17: a charge of £238m). Interest expense on retirement benefit obligation During the year we incurred £139m (2017/18: £218m, 2016/17: 209m) of interest costs in relation to our defined benefit pension obligations. See note 19 for more details. Tax on specific items A tax credit of £ 112 87 , 2016/17: 154m EE acquisition warranty claims In the prior year we reached settlements with Deutsche Telekom and Orange in respect of any warranty claims under the 2015 EE acquisition agreement, arising from the issues previously announced regarding our operations in Italy. This represents a full and final settlement of these issues and resulted in a specific item charge of £225m.

Taxation

Taxation	12 Months Ended
	Mar. 31, 2019
Taxation [Abstract]
Taxation	Significant accounting policies that apply to taxation Current income tax is calculated on the basis of the tax laws enacted or substantively enacted at the balance sheet date in the countries where the group’s subsidiaries, associates and joint ventures operate and generate taxable income. We periodically evaluate positions taken in tax returns with respect to situations in which applicable tax regulation is subject to interpretation, and establish provisions where appropriate on the basis of the amounts expected to be paid to tax authorities. Deferred tax is recognised, using the liability method, in respect of temporary differences between the carrying amount of our assets and liabilities and their tax base. Deferred tax is determined using tax rates that are expected to apply in the periods in which the asset is realised or liability settled, based on tax rates and laws that have been enacted or substantively enacted by the balance sheet date. Deferred income tax assets and liabilities are offset when there is a legally enforceable right to offset current tax assets against current tax liabilities and when the deferred income tax assets and liabilities relate to income taxes levied by the same taxation authority on either the taxable entity or different taxable entities where there is an intention to settle the balances on a net basis. Any remaining deferred tax asset is recognised only when, on the basis of all available evidence, it can be regarded as probable that there will be suitable taxable profits, within the same jurisdiction, in the foreseeable future against which the deductible temporary difference can be utilised. Deferred tax balances for which there is a right of offset within the same jurisdiction are presented net on the face of the group balance sheet as permitted by IAS 12, with the exception of deferred tax related to our pension schemes which is disclosed within deferred tax assets. Critical accounting judgements and key estimates made in accounting for taxation We seek to pay tax h w o o n i e e d u e a a e a e un a a a a a g u i a a u o o o g t g o W e i u o n b u a n i - u b a e n i a r e t h e e l a l l w h e t h e u i n o u d e l e t b a u a u i t n h e i a g u a n u e t h h o t a e W o d o t h o o w h e o u l o p a l b u h g a u a i a e l o o u a e p i l u o p i n a n e a i a o i o n h r e o t e t a e o h 1 o £ 252 0 18 £ 240 l e u n a i e i a e n n t i e U n e d u h b b Deciding whether to recognise deferred tax assets is judgemental. We only recognise them when we consider it is probable that they can be recovered. In making this judgement we consider evidence such as historical financial performance, future financial plans and trends, the duration of existing customer contracts and whether our intra-group pricing model has been agreed by the relevant tax authority. The value of the group’s income tax assets and liabilities is disclosed on the group balance sheet A n x e s Year ended 31 March 2019 £m 2018 £m 2017 £m United Kingdom Corporation tax at 19% (2017/18: 19%, 2016/17: 20%) (478 ) (614 ) (594 ) Adjustments in respect of earlier years (9 ) 37 33 Non-UK taxation Current (74 ) (66 ) (109 ) Adjustments in respect of earlier years 15 23 - Total current tax expense (546 ) (620 ) (670 ) Deferred taxation Origination and reversal of temporary differences (20 ) 46 96 Adjustments in respect of earlier years 2 (57 ) 26 Impact of change in UK corporation tax rate to 17% (2017/18: 17%, 2016/17: 17%) - - 63 Remeasurement of temporary differences 13 11 - Total deferred taxation expense (credit) (5 ) - 185 Total taxation expense (551 ) (620 ) (485 ) F a e u x a x e s y T h a o p o p e o h o p b a l n h p a t i h o f i t Year ended 31 March 2019 £m 2018 £m 2017 £m Profit before taxation 2,898 2,804 2,551 Expected taxation expense at UK rate of 19% (2017/18: 19%, 2016/17: 20%) (551 ) (533 ) (510 ) Effects of: (Higher) lower taxes on non-UK profits (7 ) (8 ) (29 ) Net permanent differences between tax and accounting a (35 ) (100 ) (183 ) Adjustments in respect of earlier years b 8 3 59 Prior year non-UK losses used against current year profits 21 16 120 Non-UK losses not recognised c - (9 ) (8 ) Other deferred tax assets not recognised - - - Lower taxes on profit on disposal of business - - 3 Re-measurement of deferred tax balances 13 11 63 Other non-recurring items - - - Total taxation expense (551 ) (620 ) (485 ) Exclude specific items (note 10) (112 ) (87 ) (217 ) Total taxation expense before specific items (663 ) (707 ) (702 ) a Includes income that is not taxable or UK income taxable at a different rate, and expenses for which no tax relief is received. Examples include some types of depreciation and amortisation and the benefit of R&D tax incentives. b Reflects the differences between initial accounting estimates and tax returns submitted to tax authorities, including the release and establishment of provisions for uncertain tax positions. c s m o e e n e c d p a o e e e f xa p n r b T a n e e e s c o m Year ended 31 March 2019 Tax credit (expense) £m 2018 Tax credit (expense) (Restated) £m 2017 Tax credit (expense) £m Tax on items that will not be reclassified to the income statement Pension remeasurements a 384 (263 ) 416 Tax on items that have been or may be reclassified subsequently to the income statement Exchange differences on translation of foreign operations (4 ) (9 ) 21 Fair value movements on cash flow hedges – net fair value gains or losses (37 ) 57 (131 ) – recognised in income and expense - (47 ) 139 343 (262 ) 445 Current tax credit b 395 203 122 Deferred tax (expense) credit (52 ) (465 ) 323 343 (262 ) 445 a Certain results have been restated to reflect the update to the calculation of our IAS 19 accounting valuation of retirement benefit obligations. See note 2. b I nclu d es £391 m (20 1 7/1 8 : £212m, 2 016 / 17: £ 110 m ) rel a ting to ca s h c o ntrib u tions ma d e to r e du c e reti r eme n t be n efit o blig a tion s. T a s e e d e n s e i Year ended 31 March 2019 £m 2018 £m 2017 £m Tax (expense) credit relating to share-based payments - (2 ) (6 ) Deferred taxation Fixed asset temporary differences £m Retirement benefit obligations b £m Share- based payments £m Tax losses £m Other £m Jurisdictional offset £m Total (Restated) £m At 1 April 2017 1,432 (1,537 ) (17 ) (270 ) (85 ) – (477 ) Expense (credit) recognised in the income statement 11 (104 ) 4 89 0 – – Expense (credit) recognised in other comprehensive income (restated) a 0 475 – 0 (10 ) – 465 Expense (credit) recognised in equity – – 6 – – – 6 Exchange differences – – – (2 ) 5 – 3 Transfer to current tax 17 – – – – – 17 At 31 March 2018 1,460 (1,166 ) (7 ) (183 ) (90 ) – 14 Non-current Deferred tax asset (41 ) (1,166 ) (7 ) (183 ) (90 ) 161 (1,326 ) Deferred tax liability 1,501 – – – – (161 ) 1,340 At 1 April 2018 1,460 (1,166 ) (7 ) (183 ) (90 ) – 14 Expense (credit) recognised in the income statement (60 ) (59 ) 1 114 (1 ) – (5 ) Expense (credit) recognised in other comprehensive income - 15 - - 37 – 52 Expense (credit) recognised in equity - - (1 ) - – – (1 ) Exchange differences - - 1 (1 ) – – – At 31 March 2019 1,400 (1,210 ) (6 ) (70 ) (54 ) – 60 Non-current Deferred tax asset (27 ) (1,210 ) (6 ) (70 ) (54 ) 20 (1,347 ) Deferred tax liability 1,427 – – – – (20 ) 1,407 At 31 March 2019 1,400 (1,210 ) (6 ) (70 ) (54 ) – 60 a b I d e t s o 1 m i n t a i i o e n T h o o d e e a a n a l e n o a n p a l e o h 1 n t h What a t a e u a r e T h o o a o 9 1 7 2 0 2 0 d e a a n l b l e u a e a a e p h e d o e a d e a b a a e a 3 2 h a b e e l a t e h h e a b a l e e e e e What n n n e e At n s e n a a t a h o o p a e o o e e h t t o p e u e o At 31 March 2019 £m Expiry Restricted losses Europe 16 2019-2038 Americas 205 2019-2038 Other 3 2019-2038 Total restricted losses 224 Unrestricted operating losses 3,905 No expiry Other temporary differences 108 No expiry Total 4,237 At h e n 1 b h u t o o At n 17/ h b en n n t o e d r d 7 23.0 s a 0 7 d a n a n d e a

Dividends

Dividends	12 Months Ended
	Mar. 31, 2019
Dividend [Abstract]
Dividends	i d d What d v e d h a v e p a a p e h ye a A dividend of £2,500m was paid to the parent company, BT Group Investments Limited, during 2018/19 2017/18: £nil, 2016/17: £2,350m) Subsequent to 31 March 2019, the directors have declared a final dividend of £ 1

Intangible assets

Intangible assets	12 Months Ended
	Mar. 31, 2019
Intangible Assets [Abstract]
Intangible assets	Significant accounting policies that apply to intangible assets We recognise identifiable intangible assets where we control the asset, it is probable that future economic benefits attributable to the asset will flow to the group, and we can reliably measure the cost of the asset. We amortise all intangible assets, other than goodwill, over their useful economic life. The method of amortisation reflects the pattern in which the assets are expected to be consumed. If the pattern cannot be determined reliably, the straight line method is used. Goodwill Goodwill represents the excess of the cost of an acquisition over the fair value of the group’s share of the identifiable net assets (including intangible assets) of the acquired business. Our goodwill impairment policy is set out later in this note. Acquired intangible assets – customer relationships and brands Intangible assets such as customer relationships or brands acquired through business combinations are recorded at fair value at the date of acquisition and subsequently carried at amortised cost. Assumptions are used in estimating the fair values of these relationships or brands and include management’s estimates of revenue and profits to be generated by them. Telecommunications licences Licence fees paid to governments, which permit telecommunications activities to be operated for defined periods, are initially recorded at cost and amortised from the time the network is available for use to the end of the licence period or where our usage can extend beyond the initial licence period, over the period we expect to benefit from the use of the licences, which is typically 20 years. Licences acquired through business combinations are recorded at fair value at the date of acquisition and subsequently carried at amortised cost. The fair value is based on management’s assumption of future cash flows using market expectations at acquisition date. Computer software Computer software comprises computer software licences purchased from third parties, and also the cost of internally developed software. Computer software licences purchased from third parties are initially recorded at cost. We only capitalise costs directly associated with the production of internally developed software, including direct and indirect labour costs of development, where it is probable that the software will generate future economic benefits, the cost of the asset can be reliably measured and technical feasibility can be demonstrated, in which case it is capitalised as an intangible asset on the balance sheet. Costs which do not meet these criteria and research costs are expensed as incurred. Our development costs which give rise to internally developed software include upgrading the network architecture or functionality and developing service platforms aimed at offering new services to our customers. Other Other intangible assets include website development costs and other licences. Items are capitalised at cost and amortised on a straight line basis over their useful economic life or the term of the contract. Estimated useful economic lives The estimated useful economic lives assigned to the principal categories of intangible assets are as follows: – Computer r 2 r – Telecommunications 2 r – Customer r n r 1 r Impairment of intangible assets Intangible assets with finite useful lives are tested for impairment if events or changes in circumstances (assessed at each reporting date) indicate that the carrying amount may not be recoverable. When an impairment test is performed, the recoverable amount is assessed by reference to the higher of the net present value of the expected future cash flows (value in use) of the relevant cash generating unit and the fair value less costs to dispose. Goodwill is reviewed for impairment at least annually as described below. Impairment losses are recognised in the income statement, as a specific item. If a cash generating unit is impaired, impairment losses are allocated firstly against goodwill, and secondly on a pro-rata basis against intangible and other assets. Goodwill £m Customer relationships and brands £m Telecoms licences and other £m Internally developed software £m Purchased software £m Total £m Cost At 1 April 2017 8,042 3,422 2,945 4,363 1,853 20,625 Additions – – – 517 125 642 Acquisitions 14 – 3 – – 17 Disposals and adjustments a (3 ) – (3 ) (55 ) (413 ) (474 ) Exchange differences (100 ) (12 ) 6 (3 ) 9 (100 ) At 31 March 2018 7,953 3,410 2,951 4,822 1,574 20,710 Additions – – 304 520 160 984 Disposals and adjustments a (2 ) – (3 ) (945 ) (141 ) (1,091 ) Transfers – – 4 120 (80 ) 44 Exchange differences 63 7 (4 ) 1 (8 ) 59 At 31 March 2019 8,014 3,417 3,252 4,518 1,505 20,706 Accumulated amortisation At 1 April 2017 – 813 280 3,193 1,302 5,588 Charge for the year – 379 141 525 78 1,123 Disposals and adjustments a – – (3 ) (36 ) (426 ) (465 ) Exchange differences – (1 ) 3 (2 ) 9 9 At 31 March 2018 – 1,191 421 3,680 963 6,255 Charge for the year – 377 142 525 110 1,154 Disposals and adjustments a – – (3 ) (941 ) (147 ) (1,091 ) Transfers – – 3 (43 ) 43 3 Exchange differences – 3 (3 ) – (8 ) (8 ) At 31 March 2019 – 1,571 560 3,221 961 6,313 Carrying amount At 31 March 2019 8,014 1,846 2,692 1,297 544 14,393 At 31 March 2018 7,953 2,219 2,530 1,142 611 14,455 a Fully depreciated assets in the group’s fixed asset registers were reviewed during the year, as part of the group’s annual asset verification exercise, and certain assets that were no longer in use have been written off, reducing cost and accumulated depreciation by £1.0bn (2017/18: £0.4bn). Impairment of goodwill Significant accounting policies that apply to impairment of goodwill We perform an annual goodwill impairment review . Goodwill recognised in a business combination does not generate cash flows independently of other assets or groups of assets. As a result, the recoverable amount, being the value in use, is determined at a cash generating unit (CGU) level. These CGUs represent the smallest identifiable groups of assets that generate cash inflows that are largely independent of the cash inflows from other groups of assets. Our CGUs are de e med to be legacy BT Consumer, legacy EE, Enterprise, and Global Services. We allocate goodwill to each of the Cash Generating Units (CGUs) that we expect to benefit from the business combination. Each CGU to which goodwill is allocated represents the lowest level within the group at which the goodwill is monitored for internal management purposes. The value in use of each CGU is determined using cash flow projections derived from financial plans approved by the Board covering a five-year period. They reflect management’s expectations of revenue, EBITDA growth, capital expenditure, working capital and operating cash flows, based on past experience and future expectations of business performance. Cash flows beyond the fifth year have been extrapolated using perpetuity growth rates. Critical accounting estimates and key judgements made in reviewing goodwill for impairment Determining o T h e i a i o u C G U i j u d e n l d n i i o C G U i n o e n w h e h e g r o u o a e a t g n e n e n l w h n e i d e o h o u e a p w h e t h e t g e n e a i e e d e e Estimating value in use Our value in use calculations require estimates in relation to uncertain items, including management’s expectations of future revenue growth, operating costs, profit margins, operating cash flows, and the discount rate for each CGU. Future cash flows used in the value in use calculations are based on our latest BT Group plc Board-approved five-year financial plans. Expectations about future growth reflect the expectations of growth in the markets to which the CGU relates. The future cash flows are discounted using a pre-tax discount rate that reflects current market assessments of the time value of money. The discount rate used in each CGU is adjusted for the risk specific to the asset, including the countries in which cash flow will be generated, for which the future cash flow estimates have not been adjusted. We tested our goodwill for impairment as at 31 December 2018. The carrying value of goodwill and the key assumptions used in performing the annual impairment assessment and sensitivities are disclosed below. Cost Legacy BT Consumer £m Legacy EE £m Enterprise £m Business and Public Sector Wholesale and Ventures Global Services £m Total £m At 1 April 2017 1,183 2,768 – 2,570 942 579 8,042 Exchange differences – – – (8 ) – (92 ) (100 ) Acquisitions and disposals – – – – – 11 11 At 31 March 2018 1,183 2,768 — 2,562 942 498 7,953 Transfer – – 3,504 (2,562 ) (942 ) – – Exchange differences – – 5 – – 58 63 Acquisitions and disposals – – – – – (2 ) (2 ) At 31 March 2019 1,183 2,768 3,509 – – 554 8,014 What d s c u a a w u s e T h d u n a p i l a a e u e h t e e g o a l he a p i n u h l a t i o o g p e h t e e g o a a e h e e a a a l a t a p i u n a i e o h u u l a i 0 1 1 8 8 . 4 W e ’ e h d o C G U e p o e e w w a e e l n g h e i i o u n e i b e op e a e What a T h What n s i w p T h g n a n e o o N o n a b p o b h n e i h u o n u a a n u e e h o a a u o l b i h u u e d a n u h p ox a e l 2 17 1 8 h o n h ng e a p i n w l u h o a a u C G q a a n u – ed u t o t h p e p t o t o h 2.4 u p e i a o – n a d o o h 8.7 a p i p l e p i o – l i i p e n g i e l t i n i e n o e i n b 42 e a e e

Property, plant and equipment

Property, plant and equipment	12 Months Ended
	Mar. 31, 2019
Disclosure Of Property Plant And Equipment [Abstract]
Property, plant and equipment	r i Significant accounting policies that apply to property, plant and equipment Our property, plant and equipment is included at historical cost, net of accumulated depreciation, government grants and any impairment charges. Property, plant and equipment acquired through business combinations are initially recorded at fair value and subsequently accounted for on the same basis as our existing assets. We derecognise items of property, plant and equipment on disposal or when no future economic benefits are expected to arise from the continued use of the asset. The difference between the sale proceeds and the net book value at the date of disposal is recognised in operating costs in the income statement. Included within the cost of network infrastructure and equipment are direct and indirect labour costs, materials and directly attributable overheads. We depreciate property, plant and equipment on a straight line basis from the time the asset is available for use, to write off the asset’s cost over the estimated useful life taking into account any expected residual value. Freehold land is not depreciated. Estimated useful economic lives The estimated useful lives assigned to principal categories of assets are as follows: Land and buildings – Freehold buildings 14 to 50 years – Short-term leasehold improvements Shorter of 10 years or lease term – Leasehold land and buildings Unexpired portion of lease or 4 0 years, whichever is the shorter Network infrastructure Transmission equipment – Duct 40 years – Cable 3 to 25 years – Fibre 5 to 20 years Exchange equipment 2 to 13 years Other network equipment 2 to 20 years Other assets – Motor vehicles 2 to 9 years – Computers and office equipment 3 to 7 years Assets held under finance leases are depreciated over the shorter of the lease term or their useful economic life. Residual values and useful lives are reassessed annually and, if necessary, changes are recognised prospectively. Network share assets Certain assets have been contributed to a network share arrangement by both EE and Hutchison 3G UK Limited, with legal title remaining with the contributor. This is considered to be a reciprocal arrangement. Our share of the assets on acquisition of EE were recognised at fair value within tangible assets, and depreciated in line with policy. Subsequent additions are recorded at cost. Impairment of property, plant and equipment We test property, plant and equipment for impairment if events or changes in circumstances (assessed at each reporting date) indicate that the carrying amount may not be recoverable. When an impairment test is performed, we assess the recoverable amount by reference to the higher of the net present value of the expected future cash flows (value in use) of the relevant asset and the fair value less costs to dispose. If it is not possible to determine the recoverable amount for the individual asset then we assess impairment by reference to the relevant cash generating unit as described in note 13. Key j g m n m a a c c n n o U c n a t We receive government grants in relation to the Broadband Delivery UK (BDUK) programme and other rural superfast broadband contracts. Where we have achieved certain service levels, or delivered the network more efficiently than anticipated, we have an obligation to either re-invest or repay grant funding. Where this is the case, we assess and defer the income with a corresponding increase in capital expenditure. Assessing the timing of whether and when we change the estimated take-up assumption is judgemental as it involves considering information which is not always observable. Our consideration on whether and when to change the base case assumption is dependent on our expectation of the long-term take-up trend. Our assessment of how much grant income to defer includes consideration of the difference between the take-up percentage agreed with the local authority and the likelihood of actual take-up. The value of the government grants deferred is disclosed in note 17. Land and buildings a £m Network infrastructure a £m Other b £m Assets in course of construction £m Total £m Cost At 31 March 2017 1,302 49,372 1,938 1,413 54,025 Additions c 12 193 92 2,597 2,894 Transfers 36 2,793 16 (2,845 ) – Disposals and adjustments d (82 ) (1,540 ) (119 ) (48 ) (1,789 ) Exchange differences (6 ) (35 ) (13 ) 1 (53 ) At 31 March 2018 1,262 50,783 1,914 1,118 55,077 Additions c 12 97 119 3,034 3,262 Transfers 13 2,988 18 (3,063 ) (44 ) Disposals and adjustments d (178 ) (1,943 ) (333 ) 102 (2,352 ) Exchange differences (2 ) (32 ) 4 – (30 ) At 31 March 2019 1,107 51,893 1,722 1,191 55,913 Accumulated depreciation At 31 March 2017 817 35,214 1,554 – 37,585 Charge for the year 57 2,213 121 – 2,391 Disposals and adjustments d (96 ) (1,613 ) (107 ) – (1,816 ) Exchange differences (5 ) (24 ) (10 ) – (39 ) At 31 March 2018 773 35,790 1,558 – 38,121 Charge for the year 51 2,236 105 – 2,392 Transfers 1 (4 ) – – (3 ) Disposals and adjustments d (104 ) (1,940 ) (296 ) – (2,340 ) Exchange differences (1 ) (30 ) 4 – (27 ) At 31 March 2019 720 36,052 1,371 – 38,143 Carrying amount At 31 March 2019 387 15,841 351 1,191 17,770 Engineering stores – – – 65 65 Total at 31 March 2019 387 15,841 351 1,256 17,835 At 31 March 2018 489 14,993 356 1,118 16,956 Engineering stores – – – 44 44 Total at 31 March 2018 489 14,993 356 1,162 17,000 a The carrying amount of the group’s property, plant and equipment includes an amount of £34m (2017/18: £53m) in respect of assets held under finance leases, comprising land and buildings of £34m (2017/18: £42m) and network infrastructure of £nil (2017/18: £11m). The depreciation expense on those assets in 2018/19 was £2m (2017/18: £10m), comprising land and buildings of £2m (2017/18: £3m) and network infrastructure of £nil (2017/18: £7m). b Other mainly comprises motor vehicles, computers and fixtures and fittings. c Net of grant deferral of £63m (2017/18: £74m net grant funding). d Fully depreciated assets in the group’s fixed asset registers were reviewed during the year, as part of the group’s annual asset verification exercise, and certain assets that were no longer in use have been written off, reducing cost and accumulated depreciation by £1.9bn (2017/18: £1.3bn). Disposals and adjustments also reflect the reclassification of the BT Centre property to held for sale (£89m), and £124m of adjustments resulting from changes in assumptions used in calculating lease-end obligations where the corresponding asset is capitalised. At 31 March 2019 £m 2018 £m The carrying amount of land and buildings, including leasehold improvements, comprised: Freehold 158 261 Leasehold 229 228 Total land and buildings 387 489 N e u S o e r t e nd a m n o e o u e h ne b o a u 8 5 n i t Within 9.0 f s

Programme rights

Programme rights	12 Months Ended
	Mar. 31, 2019
Disclosure Of Programme Rights [Abstract]
Programme rights	r i Significant accounting policies that apply to programme rights Programme rights are recognised on the balance sheet from the point at which the legally enforceable licence period begins. They are initially recognised at cost and are amortised from the point at which they are available for use, on a straight line basis over the programming period, or the remaining licence term, as appropriate, which is generally 12 months. Programme rights are tested for impairment in accordance with our impairment policy as set out in note 13. Additions g u . Programmes produced internally are charged to the income statement over the period of the related broadcast. Total £m At 1 April 2017 264 Additions 771 Amortisation (763 ) At 1 April 2018 272 Additions 879 Amortisation (841 ) At 31 March 2019 310

Trade and other receivables

Trade and other receivables	12 Months Ended
	Mar. 31, 2019
Disclosure Of Trade And Other Receivables [Abstract]
Trade and other receivables	Significant accounting policies that apply to trade and other receivables We initially recognise trade and other receivables at fair value, which is usually the original invoiced amount. They are subsequently carried at amortised cost using the effective interest method. The carrying amount of these balances approximates to fair value due to the short maturity of amounts receivable. We provide services to consumer and business customers, mainly on credit terms. We know that certain debts due to us will not be paid through the default of a small number of our customers. Because of this, we recognise an allowance for doubtful debts on initial recognition of receivables, which is deducted from the gross carrying amount of the receivable. The allowance is calculated by reference to credit losses expected to be incurred over the lifetime of the receivable. In estimating a loss allowance we consider historical experience and informed credit assessment alongside other factors such as the current state of the economy and particular industry issues. We consider reasonable and supportable information that is relevant and available without undue cost or effort. Once recognised, trade receivables are continuously monitored and updated. Allowances are based on our historical loss experiences for the relevant aged category as well as forward-looking information and general economic conditions. Allowances are calculated by individual customer-facing units in order to reflect the specific nature of the customers relevant to that customer-facing unit. At 31 March 2019 £m 2018 £m 2017 £m Current Trade receivables 1,732 1,741 1,774 Amounts owed by ultimate parent company 16 15 25 Prepayments a 698 1,103 733 Accrued income b 34 777 955 Deferred contract costs c 417 - - Other receivables d 341 393 373 3,238 4,029 3,860 At 31 March 2019 £m 2018 £m 2017 £m Non-current Other assets e 173 317 360 Deferred contract costs c 272 - - 445 317 360 a 2017/18 includes £325m b Accrued income recognised in prior years has been substantially reclassified to contract assets on adoption of IFRS 15. See notes 1 and 2. c Deferred contract costs arise following adoption of IFRS 15 on 1 April 2018. See notes 1 and 2. d Other receivables includes assets held for sale of £ nil. (2017/18: £nil, 2016/17: £22m). £89m assets held for sale as at 31 March 2019 are presented separately on the face of the balance sheet. e Other assets comprise prepayments and leasing debtors. Included in prior year comparatives are costs relating to the initial set-up, transition or transformation phase of long-term networked IT services contracts (2017/18: £145m, 2016/17: £163m), which are presented within deferred contract costs following adoption of IFRS 15. Trade receivables are stated after deducting allowances for doubtful debts, as follows: 2019 £m 2018 £m 2017 £m At 1 April 375 303 195 Expense 95 129 211 Utilised (165 ) (61 ) (114 ) Exchange differences (6 ) 4 11 At 31 March 299 375 303 Included within the 2016/17 expense above are amounts for exposures relating to the Italian business investigation. Note 25 provides further disclosure regarding the credit quality of our gross trade receivables. Trade receivables are due as follows: Past due and not specifically impaired At 31 March Not past due £m Trade receivables specifically impaired net of provision £m Between 0 and 3 months £m Between 3 and 6 months £m Between 6 and 12 months £m Over 12 months £m Total £m 2019 1,229 34 371 42 40 16 1,732 2018 1,251 61 293 44 25 67 1,741 2017 1,184 146 292 17 41 94 1,774 Gross trade receivables which have been specifically impaired amounted to £57m (2017/18: £124m, 2016/17: £238m). Trade receivables not past due and accrued income are analysed below by customer-facing unit. Trade receivables not past due Accrued income At 31 March 2019 £m 2018 £m 2017 £m 2019 £m 2018 £m 2017 £m Consumer 457 — — 32 — — Enterprise 274 — — 2 — — Global Services 498 477 444 - 222 297 Openreach - 61 1 - 67 78 BT Consumer - 157 128 - 86 90 EE - 206 335 - 122 170 Business and Public Sector - 253 200 - 134 151 Wholesale and Ventures - 92 75 - 145 167 Other - 5 1 - 1 2 Total 1,229 1,251 1,184 34 777 955 Given the broad and varied nature of our customer base, the analysis of trade receivables not past due and accrued income by customer-facing unit is considered the most appropriate disclosure of credit concentrations. Cash collateral held against trade and other receivables amounted to £9m (2017/18: £6m, 2016/17: £4m). Deferred contract costs Significant accounting policies that apply to deferred contract costs We capitalise certain costs associated with the acquisition and fulfilment of contracts with customers and amortise them over the period that we transfer the associated services. Connection costs are deferred as contract fulfilment costs because they allow satisfaction of the associated connection performance obligation and are considered recoverable. Sales commissions and other third party contract acquisition costs are capitalised as costs to acquire a contract unless the associated contract term is less than 12 months, in which case they are expensed as incurred. Capitalised costs are amortised over the minimum contract term. A portfolio approach is used to determine contract term. Where the initial set-up, transition and transformation phases of long-term contractual arrangements represent distinct performance obligations, costs in delivering these services are expensed as incurred. Where these services are not distinct performance obligations, we capitalise eligible costs as a cost of fulfilling the related service. Capitalised costs are amortised on a straight line basis over the remaining contract term, unless the pattern of service delivery indicates a more appropriate profile. To be eligible for capitalisation, costs must be directly attributable to specific contracts, relate to future activity, and generate future economic benefits. Capitalised costs are regularly assessed for recoverability. The following table shows the movement on deferred costs: Deferred connection costs £m Deferred contract acquisition costs - commissions £m Deferred contract acquisition costs - dealer incentives £m Transition and transformation £m Total £m At 1 April 2018 7 85 416 161 669 Additions 15 76 446 32 569 Amortisation (14 ) (76 ) (426 ) (53 ) (569 ) Impairment - (5 ) (4 ) (1 ) (10 ) Other 23 6 - 1 30 At 31 March 2019 31 86 432 140 689

Trade and other payables

Trade and other payables	12 Months Ended
	Mar. 31, 2019
Trade And Other Payables [Abstract]
Trade and other payables	Significant accounting policies that apply to trade and other payables We initially recognise trade and other payables at fair value, which is usually the original invoiced amount. We subsequently carry them at amortised cost using the effective interest method. At 31 March 2019 £m 2018 £m 2017 £m Current Trade payables 4,141 3,991 4,205 Amounts owed to parent company 55 50 63 Amounts owed to ultimate parent company 1 - - Other taxation and social security 564 704 704 Other payables 368 428 648 Accrued expenses 630 492 382 Deferred income a 68 1,525 1,474 5,827 7,190 7,476 At 31 March 2019 £m 2018 £m 2017 £m Non-current Other payables b 873 871 885 Deferred income a 606 455 413 1,479 1,326 1,298 a Deferred income recognised in prior periods has substantially been reclassified to contract liabilities on adoption of IFRS 15, see notes 1 and 2. The remaining balance includes £ 51 m (2017/18: £132m, 2016/17: £71m) current and £ 586 m (2017/18: £404m, 2016/17: £375m) non-current liabilities relating to the Broadband Delivery UK programme, for which grants received by the group may be subject to re-investment or repayment depending on the level of take-up. b Other payables relate to operating lease liabilities and deferred gains on a 2001 sale and finance leaseback transaction.

Provisions

Provisions	12 Months Ended
	Mar. 31, 2019
Provisions [Abstract]
Provisions	Our provisions principally relate to obligations arising from property rationalisation programmes, restructuring programmes, asset retirement obligations, network assets, insurance claims, litigation and regulatory risks. Significant accounting policies that apply to provisions We recognise provisions when the group has a present legal or constructive obligation as a result of past events, it is probable that an outflow of resources will be required to settle the obligation and the amount can be reliably estimated. Provisions are determined by discounting the expected future cash flows at a pre-tax rate that reflects current market assessments of the time value of money and the risks specific to the liability. Financial liabilities within provisions are initially recognised at fair value and subsequently carried at amortised cost using the effective interest method. We measure onerous lease provisions at the lower of the cost to fulfil or to exit the contract. C r a accounting estimates and key j g me m a a c c n n o v s n s We exercise judgement in determining the timing and quantum of all provisions to be recognised. Our assessment includes consideration of whether we have a present obligation, whether payment is probable and if so whether the amount can be estimated reliably. As part of this assessment, we also assess the likelihood of contingent liabilities occurring in the future which are not recognised as liabilities on our balance sheet. By their nature, contingencies will be resolved only when one or more uncertain future events occur or fail to occur. We assess the likelihood that a potential claim or liability will arise and also quantify the possible range of financial outcomes where this can be reasonably determined. We’ve disclosed our assessment of contingent liabilities in note 29. Restructuring programmes involve estimation of the direct cost necessary for the restructuring and exclude items that are associated with ongoing activities. The amounts below exclude restructuring costs for which the timing and amount are certain. These are recognised as part of trade and other payables. Under our property rationalisation programmes we’ve identified a number of surplus leased properties. Although efforts are being made to sublet this space, this is not always possible. Estimates have been made of the cost of vacant possession and of any shortfall arising from any potential sub-lease income being lower than the lease costs. Any such shortfall is recognised as a provision. We have also made estimates of the costs to restore properties upon vacation where this is required under the lease agreements. Asset retirement obligations (AROs) involve an estimate of the cost to dismantle equipment and restore network sites upon vacation and the timing of the event. The provision represents the group’s best estimate of the amount that may be required to settle the obligation. Network asset provisions represent our future operational costs and vacant site rentals arising from obligations relating to network share agreements. Costs are expected to be incurred over a period of up to 20 years. Our regulatory provision represents our best estimate of the cost to settle our present obligation in relation to historical regulatory matters. The charge for the year represents the outcome of management’s re-assessment of the estimates and regulatory risks across a range of issues, including price and service issues. The prices at which certain services are charged are regulated and may be subject to retrospective adjustment by regulators. Estimates are used in assessing the likely value of the regulatory risk. For all risks, the ultimate liability may vary materially from the amounts provided and will be dependent upon the eventual outcome of any settlement. Restructuring £m Property £m Network ARO £m Network share £m Regulatory £m Litigation £m Other £m Total £m At 31 March 2017 11 292 83 50 479 69 177 1,161 Additions 4 37 2 – 51 6 33 133 Unwind of discount – 11 2 2 – – – 15 Utilised or released (2 ) (46 ) (16 ) (19 ) (210 ) (11 ) (32 ) (336 ) Transfers – – – – – – 85 85 Exchange differences (1 ) – – – – – (2 ) (3 ) At 31 March 2018 12 294 71 33 320 64 261 1,055 Additions – 84 102 2 58 3 66 315 Unwind of discount – 11 2 1 – – – 14 Utilised or released – (71 ) (13 ) (9 ) (196 ) (9 ) (109 ) (407 ) Transfers (12 ) 21 – – – 27 (7 ) 29 Exchange differences – – – – – (1 ) 1 – At 31 March 2019 – 339 162 27 182 84 212 1,006 At 31 March 2019 £m 2018 £m 2017 £m Analysed as: Current 424 603 625 Non-current 582 452 536 1,006 1,055 1,161 In 2016/17 we recognised a £300m charge in relation to estimated deemed consent compensation payments. In 2016/17 a related fine of £42m was imposed and was recognised as a payable rather than as a provision. The provision movement in 2018/19 reflects the completion of the majority of deemed consent compensation payments, and new matters arising across a range of issues, including price and service issues, the re-assessment of other regulatory risks and in light of historic regulatory decisions by Ofcom. The charge has been recorded as a specific item. Included within ‘Other’ provisions are contract loss provisions of £25m (2017/18: £38m) relating to the anticipated total losses in respect of certain contracts. It is expected that the majority of these provisions will be utilised in the next few years. Although there is a short period remaining to the finalisation of these contracts, there remains uncertainty as to whether potential future changes to key assumptions made when estimating their future losses could have a significant impact. There is no single change in key variables that could materially affect future expected losses on these contracts, but it is reasonably possible there will be a combination of changes in key variables that could have a material impact. Also included in ‘Other’ are amounts provided for constructive obligations arising from insurance claims which will be utilised as the obligations are settled. During the year we have updated property provisions to reflect our reassessment of lease-end obligations to reflect the group’s property strategy announced in May 2018, and to update the rate used to discount these provisions. Where additions to the provision relate to capitalised assets there has been a corresponding increase in the asset (see note 14). Other amounts have been charged to the income statement as specific items. During the year we have updated provisions relating to asset retirement obligations to reflect our latest assessment of the cost to dismantle equipment and restore the sites, and to update the rate used to discount the provisions. The increase in the provision has been reflected in an increase in the corresponding capitalised asset (see note 14).

Retirement Benefit Plans

Retirement Benefit Plans	12 Months Ended
	Mar. 31, 2019
Disclosure Of Defined Benefit Plans [Abstract]
Retirement Benefit Plans	Background to BT’s pension plans The group has both defined benefit and defined contribution retirement benefit plans. The group’s main plans are in the UK and the largest by membership is the BT Pension Scheme (BTPS) which is a defined benefit plan that was closed to new entrants on 31 March 2001. After that date new entrants to BT in the UK have been able to join a defined contribution plan, currently the BT Retirement Saving Scheme (BTRSS), a contract-based arrangement operated by Standard Life. Sections B and C of the BTPS were closed to future benefit accrual on 30 June 2018 (which represented over 99% of the BTPS active membership at the time) and affected employees have been able to join the BTRSS for future pension accrual. Non-management employees will be eligible to join a new hybrid pension arrangement, the BT Hybrid Scheme, between 1 April 2019 and 30 September 2019. This new arrangement combines elements of both defined benefit and defined contribution pension schemes. EE Limited operates the EE Pension Scheme (EEPS), which has a defined benefit section that was closed to future benefit accrual in 2014 and a defined contribution section which is open to new joiners. We also have retirement arrangements around the world in line with local markets and culture. What h How m Defined Benefits n –cont r i –the r e –the d i d b Cont r i b n r n n r T h e h r e c n p r a u e r t p T h o r n c r i Defined e Benefits in a defined benefit plan are: – determined by the plan rules, dependent on factors such as age, years of service and pensionable pay –not n e T h e e r e p r b r f n r r T h n e e d o e w i o r c Significant accounting policies that apply to retirement benefits Defined benefit plans Our net obligation in respect of defined benefit pension plans is the present value of the defined benefit obligation less the fair value of the plan assets. The income statement expense is allocated between an operating charge and net finance income or expense. - The operating charge reflects the increase in the defined benefit obligation resulting from the pension benefit earned by active employees in the current period, the costs of administering the plans and any past service costs/credits such as those arising from curtailments or settlements. - The net finance income or expense reflects the interest on the net retirement benefit obligations recognised in the group balance sheet, based on the discount rate at the start of the year. Remeasurements of the net pension obligation are recognised in full in the group statement of comprehensive income in the year in which they arise. These comprise the impact on the defined benefit obligation of changes in demographic and financial assumptions compared with the start of the year, actual experience being different to those assumptions and the return on plan assets being above or below the amount included in the net pension interest expense. Defined contribution plans Amounts in the financial statements Group income statement The expense or income arising from all group retirement benefit arrangements recognised in the group income statement is shown below. Year ended 31 March 2019 £m 2018 £m 2017 £m Recognised in the income statement before specific items – Service cost (including administration expenses & PPF levy): – defined benefit plans 135 376 281 – defined contribution plans 476 265 240 – Past service credit a – (17 ) – Subtotal 611 624 521 Recognised in the income statement as specific items (note 10) – Costs to close BT Pension Scheme and provide transition payments b 23 – – – Cost to equalise benefits between men and women due to guaranteed minimum pension (GMP) c 26 – – – Net interest expense on pensions deficit included in specific items 139 218 209 Subtotal 188 218 209 Total recognised in the income statement 799 842 730 a Relates to the removal of future indexation obligations following changes to the benefits provided under certain pension plans operating outside the UK in 2017/18 b c Group balance sheet The net pension obligation in respect of defined benefit plans reported in the group balance sheet is set out below. The prior year retirement benefit obligation has been restated as a result of a prior period accounting error, refer to note 2 for more details. 2019 2018 At 31 March Assets £m Present value of liabilities £m Deficit £m Assets £m Present value of liabilities (Restated) £m Deficit (Restated) £m BTPS 52,186 (58,855 ) (6,669 ) 49,894 (56,259 ) (6,365 ) EEPS 816 (997 ) (181 ) 763 (920 ) (157 ) Other plans a 362 (694 ) (332 ) 299 (624 ) (325 ) Retirement benefit obligation 53,364 (60,546 ) (7,182 ) 50,956 (57,803 ) (6,847 ) Adjustments due to effect of asset ceiling (IFRIC 14) – – Deferred tax asset 1,208 1,164 Net pension obligation (5,974 ) (5,683 ) a Included in the present value of obligations of other plans is £101m (2017/18: £97m) related to unfunded pension arrangements. Included within trade and other payables in the group balance sheet is £42m (2017/18: £17m) in respect of contributions payable to defined contribution plans. BT is not required to limit any pensions surplus or recognise additional pensions liabilities in individual plans as economic benefits are available in the form of either future refunds or reductions to future contributions. This is on the basis that IFRIC 14 applies enabling a refund of surplus following the gradual settlement of the liabilities over time until there are no members remaining in the scheme. Movements in defined benefit plan assets and liabilities The table below shows the movements on the pension assets and liabilities and shows where they are reflected in the financial statements. The prior year retirement benefit obligation has been restated as a result of a prior period accounting error, refer to note 2 for more details. Assets £m Liabilities £m Deficit £m At 31 March 2017 51,112 (60,200 ) (9,088 ) Service cost (including administration expenses and PPF levy) (67 ) (309 ) (376 ) Past service credit - 17 17 Interest on pension deficit 1,201 (1,419 ) (218 ) Included in the group income statement (577 ) Return on plan assets above the amount included in the group income statement 10 – 10 Actuarial gain arising from changes in financial assumptions a – 2,251 2,251 Actuarial loss arising from changes in demographic assumptions a – (697 ) (697 ) Actuarial gain arising from experience adjustments b – 120 120 Included in the group statement of comprehensive income 1,684 Regular contributions by employer 264 – 264 Deficit contributions by employer 872 – 872 Included in the group cash flow statement 1,136 Contributions by employees 2 (2 ) – Benefits paid (2,449 ) 2,449 – Foreign exchange 11 (13 ) (2 ) Other movements (2 ) At 31 March 2018 (Restated) 50,956 (57,803 ) (6,847 ) Service cost (including administration expenses and PPF levy) (49 ) (86 ) (135 ) Costs to close BT Pension Scheme (6) - (6 ) Cost to equalise benefits between men and women due to guaranteed minimum pension (GMP) - (26 ) (26 ) Interest on pension deficit 1,356 (1,495 ) (139 ) Included in the group income statement (306 ) Return on plan assets above the amount included in the group income statement 1,607 - 1,607 Actuarial loss arising from changes in financial assumptions a - (3,920 ) (3,920 ) Actuarial gain arising from changes in demographic assumptions a - 247 247 Actuarial loss arising from experience adjustments b - (36 ) (36 ) Included in the group statement of comprehensive income (2,102 ) Regular contributions by employer 43 - 43 Deficit contributions by employer 2,024 - 2,024 Included in the group cash flow statement 2,067 Contributions by employees 1 (1 ) - Benefits paid (2,564 ) 2,564 - Foreign exchange (4 ) 10 6 Other movements 6 At 31 March 2019 53,364 (60,546 ) (7,182 ) a The actuarial gain or loss arises from changes in the assumptions used to value the defined benefit liabilities at the end of the year compared with the assumptions used at the start of the year. This includes both financial assumptions, which are based on market conditions at the year end, and demographic assumptions such as life expectancy. b The actuarial loss or gain arising from experience adjustments on defined benefit liabilities represents the impact on the liabilities of differences between actual experience during the year compared with the assumptions made at the start of the year. Such differences might arise, for example, from members choosing different benefit options at retirement, actual salary increases being different from those assumed or actual benefit increases being different to the pension increase assumption. How do we value our retirement benefit plans? Valuation methodology The IAS 19 liabilities are measured as the present value of the estimated future benefit cash flows to be paid by each scheme, calculated using the projected unit credit method. These calculations are performed for the group by professionally qualified actuaries. The expected future benefit payments are based on a number of assumptions including future inflation, retirement ages, benefit options chosen and life expectancy and are therefore inherently uncertain. Actual benefit payments in a given year may be higher or lower, for example if members retire sooner or later than assumed, or take a greater or lesser cash lump sum at retirement than assumed. The accounting cost of these benefits and the present value of our pension liabilities involve judgements about uncertain events including the life expectancy of the members, price inflation and the discount rate used to calculate the net present value of the future pension payments. We use estimates for all of these uncertain events in determining the pension costs and liabilities in our financial statements. Our assumptions reflect historical experience, external advice and our judgement regarding future expectations. Financial assumptions are based on market expectations at the balance sheet date. The fair value of our pension asset is made up of quoted and unquoted investments. The latter require more judgement as their values are not directly observable. The assumptions used in valuing unquoted investments are affected by current market conditions and trends which could result in changes in fair value after the measurement date. How do we value the assets? Under IAS 19, plan assets must be valued at the bid market value at the balance sheet date. For the main asset categories: – Equities listed on recognised stock exchanges are valued at closing bid prices. – Properties are valued on the basis of open market value. – Bonds are measured using a combination of broker quotes and pricing models making assumptions for credit risk, market risk and market yield curves. – Holdings in investment funds are valued at fair value which is typically the Net Asset Value provided by the investment manager. – Certain unlisted investments are valued using a model based valuation such as a discounted cash flow. – The value of the longevity insurance contract held by the BTPS is measured by discounting the projected cash flows payable under the contract (projected by an actuary, consistent with the terms of the contract). Overview and governance of the BTPS What is the profile of the BTPS? At 31 March 2019 there were 288,000 members of the BTPS. Members belong to one of three sections depending upon the date they first joined the BTPS. The membership is analysed below. Analysis of BTPS Active members Deferred members Pensioners Total Sections A and B liabilities (£bn) a - 9.0 31.5 40.5 Section C liabilities (£bn) - 14.1 4.3 18.4 Total IAS 19 liabilities (£bn) - 23.1 35.8 58.9 Total number of members - b 83,000 205,000 288,000 a Sections A and B have been aggregated in this table as Section A members have typically elected to take Section B benefits at retirement. b At 31 March 2019 there are around 50 active members in the BTPS The estimated duration of the BTPS liabilities, which is an indicator of the weighted average term of the liabilities, is around 16 years although the benefits payable by the BTPS are expected to be paid over more than 70 years. Whilst benefit payments are expected to increase over the earlier years, the value of the liabilities is expected to reduce. The chart below illustrates the estimated benefits payable from the BTPS forecast using the IAS 19 assumptions. a Based on accrued benefits to 30 June 2018. What are the benefits under the BTPS? Benefits earned for pensionable service prior to 1 April 2009 are based upon a member’s final salary and a normal pensionable age of 60. Between 1 April 2009 and 30 June 2018, Section B and C active members accrued benefits based upon a career average re-valued earnings (CARE) basis and a normal pensionable age of 65. On a CARE basis benefits are built up based upon earnings in each year and the benefit accrued for each year is increased by the lower of inflation or the individual’s actual pay increase in each year to retirement. Under the Scheme rules the determination of the rate of inflation for statutory minimum rates of revaluation and indexation for the majority of benefits is based upon either the Retail Price Index (RPI) or the Consumer Price Index (CPI) which apply to each category of member as shown below. A c m Deferred m Pensioners Sec t B a B e t P r e r retirement e C P Inc r n r r C Sec t Inc r n r r R x i 5 a Section A members have typically elected to take Section B benefits at retirement . In December 2018, the Court of Appeal upheld the High Court’s ruling that it is currently not possible to change the index used to calculate pension increases paid in the future to members of Section C of the BTPS from RPI to another index. BT is seeking permission to appeal the decision from the Supreme Court. How is the BTPS governed and managed? BT Pension Scheme Trustees Limited (the Trustee) has been appointed by BT as an independent trustee to administer and manage the BTPS on behalf of the members in accordance with the terms of the BTPS Trust Deed and Rules and relevant legislation (principally the Pension Schemes Act 1993, the Pensions Act 1995 and the Pensions Act 2004). Under the terms of the Trust Deed there are nine Trustee directors, all of whom are appointed by BT, as illustrated below. Trustee directors are usually appointed for a three-year term but are then eligible for re-appointment. BTPS assets Asset allocation The allocation of assets between different classes of investment is reviewed regularly and is a key factor in the Trustee’s investment policy. The allocations reflect the Trustee’s views on the appropriate balance to be struck between seeking returns and incurring risk, and on the extent to which the assets should be allocated to match liabilities. Current market conditions and trends are regularly assessed which may lead to adjustments in the asset allocation. The fair value of the assets of the BTPS analysed by asset category are shown below. These are subdivided by assets that have a quoted market price in an active market and those that do not (such as investment funds). 2019 a 2018 a Total assets £bn of which quoted b £bn Total % Total assets £bn of which quoted b £bn Total % Growth Equities UK 0.5 0.4 1 0.5 0.5 1 Overseas developed 7.7 7.3 15 7.8 7.3 16 Emerging markets 1.1 1.1 2 0.5 0.4 1 Private Equity 1.5 – 3 1.9 – 4 Property UK 3.5 – 7 3.9 – 8 Overseas 1.1 – 2 1.2 – 2 Other growth assets Absolute Return c 1.2 – 2 1.5 – 3 Non Core Credit d 3.8 1.1 7 3.4 1.0 7 Mature Infrastructure 1.4 – 3 1.4 – 3 Liability matching Government bonds UK Index Linked 13.2 13.2 25 12.5 12.5 25 Investment grade credit Global 14.3 10.1 27 10.0 8.0 20 Cash, derivatives and other Cash balances 2.7 – 5 3.8 – 7 Longevity insurance contract e (0.7 ) – (1 ) (0.4 ) – (1 ) Other f 0.9 – 2 1.9 – 4 Total 52.2 33.2 100 49.9 29.7 100 a b Assets with a quoted price in an active market. c This allocation seeks to generate returns irrespective of the direction of markets. Managers within this allocation will typically manage their portfolios without close regard to a specific market benchmark. d This allocation includes a range of credit investments, including emerging market, sub-investment grade and unrated credit. The allocation seeks to exploit investment opportunities within credit markets using the expertise of a range of specialist investment managers. e The Trustee has hedged some of the Scheme’s longevity risk through a longevity insurance contract which was entered into in 2014. The value reflects experience to date on the contract from higher than expected deaths. This amount partly offsets a reduction which would be recognised in the Scheme’s liabilities over time. f Includes collateral posted in relation to derivatives held by the Scheme. IAS 19 assumptions The table below summarises the approach used to set the key IAS 19 assumptions for the BTPS. Approa c s t h s Disc o IAS 19 requires that the discount rate is determined by reference to market yields at the reporting date on high quality corporate bonds. The currency and term of these should be consistent with the currency and estimated term of the pension obligations. The assumption is calculated by applying the projected BTPS benefit cash flows to a corporate bond yield curve constructed by our external actuary based on the yield on AA-rated corporate bonds. In setting the yield curve, judgement is required on the selection of appropriate bonds to be included in the universe and the approach used to then derive the yield curve. RPI o The RPI inflation assumption is set using an inflation curve derived from market yields on government bonds, weighted by projected BTPS benefit cash flows, and making an adjustment for an inflation risk premium (to reflect the extra premium paid by investors for inflation protection), which is currently assumed to be 20bps. CPI o CPI P k i i Pensi o n Benefits are assumed to increase in line with the RPI or CPI inflation assumptions, based on the relevant index for increasing benefits, as prescribed by the rules of the BTPS and summarised above. Lo n v The longevity assumption takes into account: – the actual mortality experience of the BTPS pensioners, based on a formal review conducted at the 2014 triennial funding valuation – future improvements in longevity based on a model published by UK actuarial profession’s Continuous Mortality Investigation (using the CMI 2017 Mortality Projections model with a 1.25% per year long-term improvement parameter) The key financial assumptions used to measure the liabilities of the BTPS are shown below. Nominal rates (per year) Real rates (per year) a At 31 March 2019 % 2018 % 2017 % 2019 % 2018 % 2017 % Rate used to discount liabilities 2.35 2.65 2.40 (0.87 ) (0.44 ) (0.78 ) Inflation – increase in RPI 3.25 3.10 3.20 – – – Inflation – increase in CPI 2.25 b 2.00 c 2.00 d (1.0) b (1.1) c (1.2) d a The real rate is calculated relative to RPI inflation. b Assumed to be 0.1% lower until 31 March 2023. c Assumed to be 0.1% higher until 31 March 2023. d Assumed to be 0.5% higher until 31 March 2019 The BTPS represents over 97% of the group’s retirement benefit obligation. While the financial assumptions may vary for each plan, the nominal financial assumptions weighted by liabilities across all plans are equal to the figures shown in the table above (to the nearest 0.05%). B a h e a pe a o m b g 6 a f o At 31 March 2019 Number of years 2018 Number of years Male in lower pay bracket 25.7 25.8 Male in medium pay bracket 27.0 27.1 Male in higher pay bracket 28.5 28.5 Female in lower pay bracket 28.5 28.5 Female in higher pay bracket 28.7 28.7 Average improvement for a member retiring at age 60 in 10 years' time 0.7 0.7 R i k d r y n h s u p n Background The BTPS t p e a n e u o h g l a h b e o a a u e n u e d e i e u o a [•] Changes in exte r n r n e a e a a a t h a p n p a t n h a u e n o n u n i a a n u n u n n t a S o Chan g A f o t o r t w i t re I A The S s Chan g a expec t n A r t i o e e r a n e a e a The S v Chan g e An a r increase T The c B Other r n r e i m value o l b i i e Quantification B T r Scenario 1-in-20 events 2019 2018 1. Fall in discount rate a 1.1 % 1.1 % 2. Increase to inflation rate b 0.7 % 0.7 % 3. Fall in equity markets c 30.0 % - 4. Increase to life expectancy 1.25 years 1.35 years a Scenario assumes a fall in the yields on both government and corporate bonds. b Assuming RPI, CPI, pension increases and salary increases all increase by the same amount. c Scenario ignores any potential benefit from derivatives held by the scheme. T h a h d a n a looks at each event in isolation i a i b a o Sensitivity analysis of the principal assumptions to 1-in-20 events used to measure BTPS IAS 19 liabilities T h i t i o d e i l w o b o h a n g l b l n a h n i h e o e p h n i d e d i e a n n a i o o p e o e i h l u o i n a o l d T h i t i e h a b p e n p o a a 2 0 1 h i n l l a t i n a l a e n e a u p n a e d B T n n Trie n n n l T h i n a u o e u h b p f i a l q l e d e p d n a u h p o o a u a t i o i to d e i n d i l e n h B f u n e h l a u d n a u w a e o a a 3 h e d n u l a e f o l a u T h u o o l g n d n u e w h i b a e p d u n b d l – A a e u h l u a t i a – Li a l e u o a u a d n a n h o e e n e d o n o n e h p r e n T h l t o o e e n a u n o b e o June 2017 valuation £bn June 2014 valuation £bn BTPS liabilities (60.4 ) (47.2 ) Market value of BTPS assets 49.1 40.2 Funding deficit (11.3 ) (7.0 ) Percentage of accrued benefits covered by BTPS assets at valuation date 81.3% 85.2% Percentage of accrued benefits on a solvency basis covered by the BTPS assets at the valuation date 62.2% 63.0% K e s u p o n n v l a These valuations were determined using the following prudent long-term assumptions. Nominal rates (per year) Real rates (per year) a June 2017 valuation % June 2014 valuation % June 2017 valuation % June 2014 valuation % Average single equivalent discount rate 2.6 4.5 (0.8 ) 1.0 Average long-term increase in RPI 3.4 3.5 – – Average long-term increase in CPI 2.4 2.5 (1.0 ) (1.0 ) a T he r e al ra t e is c alcu l ated relat i ve to RPI i n flati o n and is s h own as a com p arat o r . T h o n a u 2 0 1 d e e o p d n e e a t i o n a b o e b a e g n a s t u u n a a u h i u n d u n 1.4 e b l u n l n i d o 0.7 e e b u l o n g h a p i e i l u n o n 1.0 p e a T h a g l p e n a o n h a a d a o e e 6 a o g a l w Number of years from valuation date June 2017 assumptions June 2014 assumptions Male in lower pay bracket 25.9 26.1 Male in medium pay bracket 27.2 27.5 Male in high pay bracket 28.6 29.0 Female in lower pay bracket 28.6 28.9 Female in high pay bracket 28.9 29.2 Average improvement for a member retiring at age 60 in 10 years’ time 0.9 1.3 Payments made to the BTPS Year ended 31 March 2019 £m 2018 £m Ordinary contributions 33 248 Deficit contributions 2,000 850 Total contributions in the year 2,033 1,098 Fut u r u i b g i a ec v e Under the terms of the Trust Deed, the group is required to have a funding plan, determined at the conclusion of the triennial funding valuation, which is a legal agreement between BT and the Trustee and should address the deficit over a maximum period of 20 years. In May 2018, the 2017 triennial funding valuation was finalised, agreed with the Trustee and certified by the Scheme Actuary. The funding deficit at 30 June 2017 was £11.3bn. The deficit was agreed to be met over a 13 year period, with the remaining payments shown in the table below. BT h u e a d e e i w h l e w Year to 31 March 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 Deficit contribution (£m) 1,250 a 900 b 900 c 907 907 907 907 907 907 907 907 a payable by 30 June 2019. b £400m payable by 30 June 2020. c £200m payable by 30 June 2021. Based on the 2017 funding valuation agreement, the group expects to make contributions of approximately £1,310m to the BTPS in 2019/20, comprising of contributions of approximately £60m for expenses and future accrual and deficit contributions of £1,250m. Other e c i T h 17 n d n g e n i n u d e d o n a e e p d p p o r h P i n l e F e u Detail S h e l e i u n BT w p d p a n B T This will p l u n n a i n e u o BT Material c r v In e n a g e n e n e a o d a e h £ o d o l n o a i n i n 1 2 o e o n n u e w a d o n a b u o n h e a h h n e a o e BT – it o i i a u o o o a 1.0 i n 1 2 n e i d – it o i i d o l o h 1.0 n o – it considers making a Class 1 transaction (acquisition or disposal); or – it is s u t a e e o This obligation is on-going until otherwise terminated. BT t e t m a Negative A negative pledge that future creditors will not be granted superior security to the BTPS in excess of a £1.5bn threshold, to cover both British Telecommunications plc and BT Group plc. This provision applies until the deficit reduces to below £2.0bn at any subsequent funding valuation. In h g h n i e n h h u e o n e n h a r d o p o n b b e s F e u Detail Cro w G a e The Crown Guarantee was granted by the Government when the group was privatised in 1984 and would only come into effect upon the insolvency of BT. The Trustee brought court proceedings to clarify the scope and extent of the Crown Guarantee. The Court of Appeal judgment on 16 July 2014 established that: –the Crown Guarantee covers BT’s funding obligation in relation to the benefits of members of the BTPS who joined post-privatisation as well as those who joined pre-privatisation (subject to certain exceptions) –the funding obligation to which the Crown Guarantee relates is measured with reference to BT’s obligation to pay deficit contributions under the rules of the BTPS. The Crown Guarantee is not taken into account for the purposes of the actuarial valuation of the BTPS and is an entirely separate matter, only being relevant in the highly unlikely event that BT became insolvent. P e s o t c u F The Pension Protection Fund (PPF) may take over the BTPS and pay benefits not covered by the Crown Guarantee to members. There are limits on the amounts paid by the PPF and the PPF would not provide exactly the same benefits as those provided under the BTPS Rules. Other e e p a In a d d h u i n i n n a n o u n h o i o e e p p h o c a e a n cu u e. EE The EEPS s e i e i e n t i o o a n At 31 March 2019, the defined e i n e e o n u b a e i n u d i g b e i i p p a b o e u o l n i i e n n o o T h i n a u o h e i b e n e w a e o a a e e 2 5 a a g e a 0 h o u i d e 4 T h o u u d n u o BTRSS T h B S i l a e d e n n u i h i n i n e h o u w u a b e a 19 h o u o u e 388

Share-based payments

Share-based payments	12 Months Ended
	Mar. 31, 2019
Share Based Payments [Abstract]
Share-based payments	Significant accounting policies that apply to share-based payments BT Group plc operates a number of equity settled share-based payment arrangements, under which the group receives services from employees in consideration for equity instruments (share options and shares) in BT Group plc. Equity-settled share-based payments are measured at fair value at the date of grant. Market-based performance criteria and non-vesting conditions (for example, the requirement for employees to make contributions to the share purchase programme) are reflected in this measurement of fair value. The fair value determined at the grant date is recognised as an expense on a straight line basis over the vesting period, based on the group’s estimate of the options or shares that will eventually vest and adjusted for the effect of non market-based vesting conditions. Fair value is measured using either the Binomial options pricing model or Monte Carlo simulations, whichever is more appropriate to the share-based payment arrangement. Service and performance conditions are vesting conditions. Any other conditions are non-vesting conditions which have to be taken into account to determine the fair value of equity instruments granted. In the case that an award or option does not vest as a result of a failure to meet a non-vesting condition that is within the control of either counterparty, this is accounted for as a cancellation. Cancellations are treated as accelerated vesting and all remaining future charges are immediately recognised in the income statement. As the requirement to save under an employee saveshare arrangement is a non-vesting condition, employee cancellations, other than through a termination of service, are treated as an accelerated vesting. No adjustment is made to total equity for awards that lapse or are forfeited after the vesting date. Year ended 31 March 2019 £m 2018 £m 2017 £m Employee Saveshare Plans 38 42 40 Executive Share Plans: Incentive Share Plan (ISP) 6 16 – Deferred Bonus Plan (DBP) 6 4 9 Retention Share Plan (RSP) 17 21 8 Other plans – 1 – 67 84 57 What share incentive arrangements do we have? Our plans include savings-related share option plans for employees and those of participating subsidiaries, further share option plans for selected employees and a stock purchase plan for employees in the US. We also have several share plans for executives. All share-based payment plans are equity-settled. Details of these plans is set out below. Employee Saveshare Plans Under an HMRC-approved savings-related share option plan, employees save on a monthly basis, over a three or five-year period, towards the purchase of shares in BT Group plc at a fixed price determined when the option is granted. This price is usually set at a 20% discount to the market price for five-year plans and 10% for three-year plans. The options must be exercised within six months of maturity of the savings contract, otherwise they lapse. Similar plans operate for our overseas employees. Incentive Share Plan (ISP) Under the ISP, participants are entitled to these shares of BT Group plc in full at the end of a three-year period only if BT Group plc has met the relevant pre-determined corporate performance measures and if the participants are still employed by the group. For ISP awards granted in 2018/19, 2017/18 and 2016/17: 40% of each award is linked to a total shareholder return (TSR) target for a comparator group of companies from the beginning of the relevant performance period; 40% is linked to a three-year cumulative normalised free cash flow measure; and 20% to growth in underlying revenue excluding transit. Deferred Bonus Plan (DBP) Under the DBP, awards are granted annually to selected employees. Shares in BT Group plc are transferred to participants at the end of three years if they continue to be employed by the group throughout that period. Retention Share Plan (RSP) Under the RSP, awards are granted to selected employees. Shares in BT Group plc are transferred to participants at the end of a specified retention period if they continue to be employed by the group throughout that period. Under the terms of the ISP, DBP and RSP, dividends or dividend equivalents earned on shares in BT Group plc during the conditional periods are reinvested in company shares for the potential benefit of the participants. Employee Saveshare Plans Movements in Employee Saveshare options are shown below. Movement in the number of share options Weighted average exercise price Year ended 31 March 2019 millions 2018 millions 2017 millions 2019 pence 2018 pence 2017 pence Outstanding at 1 April 175 189 197 306 313 287 Granted 80 69 44 175 250 362 Forfeited (44 ) (41 ) (18 ) 298 328 345 Exercised (1 ) (30 ) (33 ) 247 169 208 Expired (20 ) (12 ) (1 ) 294 353 345 Outstanding at 31 March 190 175 189 254 306 313 Exercisable at 31 March – – – 249 320 237 The weighted average share price for all options exercised during 2018/19 was 249p (2017/18: 311p, 2016/17: 357p). The following table summarises information relating to options outstanding and exercisable under Employee Saveshare plans at 31 March 2018. Normal dates of vesting and exercise (based on calendar years) Exercise price per share Weighted average exercise price Number of outstanding options millions Weighted average remaining contractual life 2019 319p – 397p 333 p 40 10 months 2020 243p – 376p 305 p 34 22 months 2021 243p 232 p 43 34 months 2022 170p 243 p 29 46 months 2023 170p 43 58 months Total 254 p 189 34 months Executive share plans Movements in executive share plan awards during 2017/18 are shown below: Number of shares (millions) ISP DBP RSP Total At 31 March 2018 54 6 12 72 Awards granted 33 4 7 44 Awards vested – (1 ) (7 ) (8 ) Awards lapsed (18 ) (1 ) (1 ) (20 ) Dividend shares reinvested 5 5 At 31 March 2019 74 8 11 93 Fair values The following table summarises the fair values and key assumptions used for valuing grants made under the Employee Saveshare plans and ISP in 2018/19, 2017/18 and 2016/17. 2019 2018 2017 Year ended 31 March Employee Saveshare ISP Employee Saveshare ISP Employee Saveshare ISP Weighted average fair value 41 p 156 p 56 p 202 p 72p 328p Weighted average share price 208 p 211 p 296 p 281 p 422p 426p Weighted average exercise price 175 p n/a 250 p n/a 362p n/a Expected dividend yield 3.47% – 3.83% n/a 3.12% – 3.21% n/a 2.9% – 3.4% n/a Risk free rates 0.74% – 1.07% 0.7 % 0.1% – 0.2% 0.2 % 0.5% – 0.8% 0.6% Expected volatility 23.3% – 25.8% 23.5 % 23.1% – 24.3% 23.6 % 19.0% – 21.5% 21.8% Employee Saveshare grants are valued using a Binomial options pricing model. Awards under the ISP are valued using Monte Carlo simulations. TSRs are generated for BT and the comparator group at the end of the three-year performance period, using each company’s volatility and the cross correlation between pairs of stocks. Volatility has been determined by reference to BT Group plc’s historical volatility which is expected to reflect the BT Group plc share price in the future. An expected life of three months after vesting date is assumed for Employee Saveshare options. For all other awards the expected life is equal to the vesting period. The risk-free interest rate is based on the UK gilt curve in effect at the time of the grant, for the expected life of the option or award. The fair values for the DBP and RSP were determined using the market price of the shares at the grant date. The weighted average share price for DBP awards granted in 2018/19 was 209

Investments

Investments	12 Months Ended
	Mar. 31, 2019
Disclosure Of Investments [Abstract]
Investments	Significant accounting policies that apply to investments Investments classified as amortised cost These investments are Investments classified as fair value through profit and loss These investments are initially recognised at fair value plus direct transaction costs. They are re-measured at subsequent reporting dates to fair value and changes are recognised directly in the income statement. Debt instruments classified as fair value through other comprehensive income These investments are initially recognised at fair value plus direct transaction costs. Investments are re-measured at subsequent reporting dates to fair value, and unrealised gains and losses are recognised in other comprehensive income (except for changes in exchange rates for monetary items, interest, and impairment losses, which are recognised in the income statement). On derecognition of the investment, the cumulative gain or loss previously recognised in other comprehensive income is taken to the income statement, in the line that most appropriately reflects the nature of the item or transaction. Equity instruments classified as fair value through other comprehensive income We have made an irrevocable election to present changes in the fair value of equity investments that are not held for trading in other comprehensive income. All gains or losses are recognised in other comprehensive income and are not reclassified to the income statement when the investments are disposed of, aside from dividends which are recognised in the income statement when our right to receive payment is established. Equity investments are recorded in non-current assets unless they are expected to be sold within one year. IFRS 9 was applied for the first time on 1 April 2018 and introduces new classifications for financial instruments, including investments. Under IAS 39, we classified investments as available-for-sale, loans and receivables, and fair value through profit or loss. On transition to IFRS 9 we have reclassified them as fair value through other comprehensive income, fair value through profit or loss, and amortised cost, as set out in note 1. The current year figures in the following table reflect the classifications under IFRS 9, and the prior year figures reflect the previous classifications under IAS 39. Amounts owed by parent companies, classified as loans and receivables under IAS39, are classified as amortised cost under IFRS9, which has not changed the accounting for these investments. At 31 March 2019 £m 2018 £m 2017 £m Non-current assets Fair value through other comprehensive income 48 – – Available-for-sale – 46 37 Amounts owed by ultimate parent company 3,029 2,983 1,371 Amounts owed by parent company 10,436 10,318 10,191 Fair value through profit or loss 6 7 7 13,519 13,354 11,606 Current assets Fair value through other comprehensive income – – – Available-for-sale – 2,575 1,437 Amounts owed by ultimate parent company 61 34 28 Amounts owed by parent company 211 168 192 Investment held at amortised cost 3,214 – – Loans and receivables – 447 83 3,486 3,224 1,740 Investments held at amortised cost consist of investments previously classified as loans and receivables and relate to money market investments s : £18m ). Fair value estimation Fair value hierarchy At 31 March 2019 Level 1 £m Level 2 £m Level 3 £m Total held at fair value £m Non-current and current investments Fair value through other comprehensive income 38 – 10 48 Fair value through profit or loss 6 – – 6 Total 44 – 10 54 At 31 March 2018 Level 1 £m Level 2 £m Level 3 £m Total held at fair value £m Non-current and current investments Available-for-sale 32 2,575 14 2,621 Fair value through profit or loss 7 – – 7 Total 39 2,575 14 2,628 At 31 March 2017 Level 1 £m Level 2 £m Level 3 £m Total held at fair value £m Non-current and current investments Available-for-sale 21 1,437 16 1,474 Fair value through profit or loss 7 – – 7 Total 28 1,437 16 1,481 The three levels of valuation methodology used are: Level 1 – uses quoted prices in active markets for identical assets or liabilities. Level 2 – uses inputs for the asset or liability other than quoted prices that are observable either directly or indirectly. Level 3 – uses inputs for the asset or liability that are not based on observable market data, such as internal models or other valuation method. Level 2 balances disclosed in prior years consist of investments classified as available-for-sale and relating to liquidity funds denominated in sterling of £2,180m (2017/18) and £900m (2016/17), and in euros of £395m (2017/18) and £537m (2016/17). Their fair value was calculated by using notional currency amounts adjusted by year end spot exchange rates. These have been reclassified on adoption of IFRS 9 and are now held at amortised cost. Level 3 balances consist of investments classified as fair value through comprehensive income (previously available-for-sale) of £10m (2017/18: £14m, 2016/17: £16m) which represent investments in a number of private companies. In the absence of specific market data, these investments are held at cost, adjusted as necessary for impairments, which approximates to fair value.

Cash and cash equivalents

Cash and cash equivalents	12 Months Ended
	Mar. 31, 2019
Cash And Cash Equivalents [Abstract]
Cash and cash equivalents	Significant accounting policies that apply to cash and cash equivalents Cash and cash equivalents comprise cash in hand and current balances with banks and similar institutions, which are readily convertible to cash and are subject to insignificant risk of changes in value and have an original maturity of three months or less. All are held at amortised cost on the balance sheet, equating to fair value. For the purpose of the consolidated cash flow statement, cash and cash equivalents are as defined above net of outstanding bank overdrafts. Bank overdrafts are included within the current element of loans and other borrowings (note 23). At 31 March 2019 £m 2018 £m 2017 £m Cash at bank and in hand 493 439 467 Cash equivalents US deposits 3 26 32 UK deposits 1,132 31 1 Other deposits 36 25 26 Total cash equivalents 1,171 82 59 Total cash and cash equivalents 1,664 521 526 Bank overdrafts (note 23) (72 ) (29 ) (17 ) Cash and cash equivalents per the cash flow statement 1,592 492 509 Cash and cash equivalents include restricted cash of £44m (2017/18: £32

Loans and other borrowings

Loans and other borrowings	12 Months Ended
	Mar. 31, 2019
Loans And Other Borrowings [Abstract]
Loans and other borrowings	r i Significant accounting policies that apply to loans and other borrowings We initially recognise loans and other borrowings at the fair value of amounts received net of transaction costs. They are subsequently measured at amortised cost using the effective interest method and, if included in a fair value hedge relationship, are re-valued to reflect the fair value movements on the associated hedged risk. The resulting amortisation of fair value movements, on de-designation of the hedge, is recognised in the income statement. Capital management policy The capital structure is managed by BT Group plc, the ultimate parent of the group. Its capital management policy is set out in the Report of the Directors The table below shows the key components of external gross debt and of the increase of £2,737m this year. At 1 April 2018 £m Issuance/ (maturities) £m Fair value movements £m Foreign exchange £m Transfer to within one year £m Accrued interest movements £m At 31 March 2019 £m Debt due within one year a 2,281 (1,423 ) (8 ) (97 ) 1,281 66 2,100 Debt due after one year 11,994 3,972 (11 ) (102 ) (1,111 ) 34 14,776 Cash flows from Derivatives related to net debt – 124 – – (124 ) – – Overdrafts – 46 – – (46 ) – – Impact of cross-currency swaps b (874 ) – – 182 – (9 ) (701 ) Removal of the accrued interest and fair value adjustments c (226 ) – 19 – – (56 ) (263 ) External gross debt 13,175 2,719 - (17 ) - 35 15,912 a Including accrued interest and bank overdrafts . b Translation of debt balances at swap rates where hedged by cross currency swaps. c Removal of accrued interest applied to reflect the effective interest rate method and removal of fair value adjustments. The table below gives the details of the listed bonds and other debt. At 31 March 2019 £m 2018 £m 2017 £m 6.625% £500m bond due June 2017 a - - 526 5.95% US$1,100m bond due January 2018 a - - 891 3.25% €600m bond due August 2018 a - 541 539 2.35% US$800m bond due February 2019 a - 572 642 4.38% £450m bond due March 2019 - 455 460 1.125% €1,000m bond due June 2019 a 869 883 863 8.625% £300m bond due March 2020 300 300 300 0.625% €1,500m bond due March 2021 a 1,289 1,309 1,282 0.5% €575m bond due June 2022 a 495 502 – 1.125% €1,100m bond due March 2023 a 946 961 942 0.875% €500m bond due September 2023 a 430 - - 4.5% US$675m bond due December 2023 a 524 - - 1% €575m bond due June 2024 a 498 506 – 1% €1,100m bond due November 2024 a 943 959 – 3.50% £250m index linked bond due April 2025 433 419 403 1.75% €1,300m bond due March 2026 a 1,118 1,137 1,113 1.5% €1,150m bond due June 2027 a 993 1,009 – 2.125% €500m bond due September 2028 a 433 - - 5.125% US$700m bond due December 2028 a 542 - - 5.75% £600m bond due December 2028 710 721 731 9.625% US$2,670m bond due December 2030 a b 2,096 1,943 2,191 3.125% £500m bond due November 2031 502 502 – 3.64% £330m bond due June 2033 339 - - 1.613% £330m Indexed linked bond due June 2033 340 - - 6.375% £500m bond due June 2037 a 522 522 522 3.883% £330m bond due June 2039 340 - - 1.739% £330m Indexed linked bond due June 2039 340 - - 3.924% £340m bond due June 2042 350 - - 1.774% £340m Indexed linked bond due June 2042 351 - - 3.625% £250m bond due November 2047 250 250 – Total listed bonds 15,953 13,491 11,405 Finance leases 206 223 229 2.21% £350m bank loan due December 2017 – – 352 Other loans 645 532 710 Bank overdrafts (note 22) 72 29 17 Amounts due to ultimate company c 2,101 1,061 1,183 Total other loans and borrowings 2,818 1,622 2,262 Total loans and borrowings 18,977 15,336 13,896 a Designated in a cash flow hedge relationship. b The interest rate payable on this bond attracts an additional 0.25% for a downgrade by one credit rating by either Moody’s or Standard & Poor’s to the group’s senior unsecured debt below A3/A–respectively. In addition, if Moody’s or Standard & Poor’s subsequently increase the ratings then the interest rate will be decreased by 0.25% for each rating category upgrade by each rating agency. In no event will the interest rate be reduced below the minimum rate reflected in the above table. c Amounts due to ultimate parent company are denominated in sterling and incur a floating rate of interest based on LIBOR. Unless previously designated in a fair value hedge relationship, all loans and other borrowings are carried on our balance sheet at amortised cost and in the table above. The fair value of listed bonds and other long-term borrowings is £17,785m (2017/18: £14,878m, 2016/17: £13,496m) and the fair value of finance leases is £251m (2017/18: £253m, 2016/17: £273m). T h a u u b d o o g e b o w n g e b a i o u a e a o a uanc he t h e e T h n o e o n a n b a n o d r a q a e a u u m a T h e a e p a a o o n a n b o w g l o e o p h n l e o a o o n g a n n o h n e a e i e h u p l a i o n a n i n e a p h e d a a g e n L o n o At 31 March 2019 £m 2018 £m 2017 £m Current liabilities Listed bonds 1,367 1,702 1,539 Finance leases 16 18 15 Bank loans – – 352 Other loans and bank overdrafts a 717 561 726 Amounts due to ultimate parent company 1,040 17 159 Total current liabilities 3,140 2,298 2,791 Non-current liabilities Listed bonds 14,586 11,789 9,866 Finance leases 190 205 214 Other loans – – 1 Amounts due to ultimate parent company 1,061 1,044 1,024 Total non-current liabilities 15,837 13,038 11,105 Total 18,977 15,336 13,896 a Incl u des c olla t eral r e cei v ed on sw a ps of £638m (2 0 17/ 18 : £525 m , 20 16 /17: £702 m). T h n l i o h b b e b a a e a o i o a d u e e n e a n a a u a d j u n t h l e n l n o b o o n h d e n a i n p a e e h a a f i o n o h e n e a i e g a i n p w h e h a l l w a i a e e l o w i ng a at 3 2 0 19 2 0 18 n 0 e n u The p n p a e a n o a n n o o g a e ge a e o £17,970 2 2 £12,138 a n e a d u a l w 2019 2018 2017 At 31 March Carrying amount £m Effect of hedging and interest £m Principal repayments at hedged rates £m Carrying amount £m Effect of hedging and interest £m Principal repayments at hedged rates £m Carrying amount £m Effect of hedging and interest £m Principal repayments at hedged rates £m Within one year, or on demand 3,140 (307 ) 2,833 2,289 (308 ) 1,981 2,791 (523 ) 2,268 Between one and two years 1,309 (133 ) 1,176 1,192 (66 ) 1,126 1,614 (197 ) 1,417 Between two and three years 15 - 15 1,332 (154 ) 1,178 1,166 (43 ) 1,123 Between three and four years 1,463 (89 ) 1,374 18 – 18 1,295 (121 ) 1,174 Between four and five years 964 33 997 1,489 (111 ) 1,378 12 – 12 After five years 12,036 (461 ) 11,575 8,943 (405 ) 8,538 6,868 (724 ) 6,144 Total due for repayment after more than one year 15,787 (650 ) 15,137 12,974 (736 ) 12,238 10,955 (1,085 ) 9,870 Total repayments 18,927 (957 ) 17,970 15,263 (1,044 ) 14,219 13,746 (1,608 ) 12,138 Fair value adjustments 50 73 150 Total loans and other borrowings 18,977 15,336 13,896 O b g n d a l e n l a l w 2019 2018 2017 2019 2018 2017 Minimum lease payments Repayment of outstanding lease obligations At 31 March £m £m £m £m Amounts payable under finance leases: Due within one year 29 33 29 16 18 14 Between two to five years 109 122 102 66 71 50 After five years 159 193 237 120 130 165 297 348 368 202 219 229 Less: future finance charges (95 ) (129 ) (139 ) – – – Fair value adjustments for purchase price adjustment 4 4 – 4 4 – Total finance lease obligations 206 223 229 206 223 229 Assets e b a b

Finance expense

Finance expense	12 Months Ended
	Mar. 31, 2019
Disclosure Of Finance Income Expense [Abstract]
Finance expense	Year ended 31 March 2019 £m 2018 £m 2017 £m Finance expense Interest on: Financial liabilities at amortised cost and associated derivatives 582 478 567 Finance leases 13 16 15 Derivatives - 14 12 Fair value movements on derivatives not in a designated hedge relationship (3 ) 1 (2 ) Reclassification of cash flow hedge from other comprehensive income 45 34 (1 ) Unwinding of discount on provisions 14 15 16 Interest payable on ultimate parent company borrowings 43 18 25 Total finance expense before specific items 694 576 632 Specific items (note 10) 139 218 210 Total finance expense 833 794 842 Year ended 31 March 2019 £m 2018 £m 2017 £m Finance income Interest on available-for-sale investments - 5 6 Interest on loans and receivables 34 7 7 Interest income on loans to immediate and ultimate parent company 272 203 219 Total finance income 306 215 232 Year ended 31 March 2019 £m 2018 £m 2017 £m Net finance expense before specific items 388 361 400 Specific items (note 10) 139 218 210 Net finance expense 527 579 610

Financial instruments and risk

Financial instruments and risk management	12 Months Ended
	Mar. 31, 2019
Text Block1 [Abstract]
Financial instruments and risk management	Risk management is performed by BT Group plc, the ultimate parent company of the group. We issue or hold financial instruments mainly to finance our operations; to finance corporate transactions such as dividends, share buybacks and acquisitions; for the temporary investment of short-term funds; and to manage currency and interest rate risks. In addition, various financial instruments, for example trade receivables and payables arise directly from operations. How do we manage financial risk? Our activities expose us to a variety of financial risks: market risk (including interest rate risk and foreign exchange risk), credit risk and liquidity risk. Treasury operation We have a centralised treasury operation whose primary role is to manage liquidity and funding requirements as well as our exposure to associated market risks, and credit risk. Treasury policy Treasury policy is set by the BT Group plc Board. Group treasury activities are subject to a set of controls appropriate for the magnitude of borrowing, investments and group-wide exposures. The BT Group plc Board has delegated authority to operate these policies to a series of panels responsible for the management of key treasury risks and operations. Appointment to and removal from the key panels requires approval from two of the following: the chairman, the chief executive or the chief financial officer BT Group plc. There has been no change in the nature of our risk profile between 31 March 2019 and the date of approval of these financial statements. How do we manage interest rate risk? Management policy Interest rate risk arises primarily from our long-term borrowings. Interest cash flow risk arises from borrowings issued at variable rates, partially offset by cash held at variable rates. Fair value interest rate risk arises from borrowings issued at fixed rates. Our policy, as set by the BT Group plc Board, is to ensure that at least 70% of BT Group plc’s ongoing net debt is at fixed rates. Short-term interest rate management is delegated to the treasury operation while long-term interest rate management decisions require further approval by the BT Group plc group chief financial officer, group director tax, treasury, insurance and pensions or the treasury director who each have been delegated such authority from the BT Group plc Board. Hedging strategy In order to manage our interest rate profile, we have entered into cross-currency and interest rate swap agreements to vary the amounts and periods for which interest rates on borrowings are fixed. The duration of the swap agreements matches the duration of the debt instruments. The majority of the group’s long-term borrowings are subject to fixed sterling interest rates after applying the impact of these hedging instruments. How do we manage foreign exchange risk? Management policy Foreign currency hedging activities protect the group from the risk that changes in exchange rates will adversely affect future net cash flows. The BT Group plc Board’s policy for foreign exchange risk management defines the types of transactions typically covered, including significant operational, funding and currency interest exposures, and the period over which cover should extend for each type of transaction. The BT Group plc Board has delegated short-term foreign exchange management to the treasury operation and long-term foreign exchange management decisions require further approval from the BT Group plc group chief financial officer, group director tax, treasury, insurance and pensions or the treasury director. Hedging strategy A significant proportion of our external revenue and costs arise within the UK and are denominated in sterling. Our non-UK operations generally trade and are funded in their functional currency which limits their exposure to foreign exchange volatility. We enter into forward currency contracts to hedge foreign currency capital purchases, purchase and sale commitments, interest expense and foreign currency investments. The commitments hedged are principally denominated in US dollar, euro and Asia Pacific region currencies. As a result, our exposure to foreign currency arises mainly on non-UK subsidiary investments and on residual currency trading flows. We use cross-currency swaps to swap foreign currency borrowings into sterling. The table below reflects the currency and interest rate profile of our loans and borrowings after the impact of hedging. 2019 2018 2017 At 31 March Fixed rate interest £m Floating rate interest £m Total £m Fixed rate interest £m Floating rate interest £m Total £m Fixed rate interest £m Floating rate interest £m Total £m Sterling 13,556 3,825 17,381 11,990 1,720 13,710 9,633 1,864 11,497 Euro – 589 589 – 509 509 – 641 641 Total 13,556 4,414 17,970 11,990 2,229 14,219 9,633 2,505 12,138 Ratio of fixed to floating 75 % 25 % 100% 84 % 16 % 100% 79 % 21 % 100% Weighted average effective fixed interest rate – sterling 4.0 % 4.4 % 4.9 % The floating rate loans and borrowings bear interest rates fixed in advance for periods ranging from one day to one year, primarily by reference to LIBOR quoted rates, RPI and CPI. Sensitivity analysis The income statement and shareholder’s equity are exposed to volatility arising from changes in interest rates and foreign exchange rates. To demonstrate this volatility, management have concluded that the following are reasonable benchmarks for performing sensitivity analysis: – For interest, a 1% increase in interest rates and parallel shift in yield curves across sterling, US dollar and euro currencies. – For foreign exchange, a 10% strengthening/weakening in sterling against other currencies. The impact on equity, before tax, of a 1% increase in interest rates and a 10% strengthening in sterling against other currencies is as detailed below: At 31 March 2019 £m Increase (reduce) 2018 £m Increase (reduce) 2017 £m Increase (reduce) Sterling interest rates 672 628 554 US dollar interest rates (350 ) (267 ) (348 ) Euro interest rates (399 ) (401 ) (229 ) Sterling strengthening (219 ) (236 ) (269 ) A 1% decrease in interest rates and 10% weakening in sterling against other currencies would have broadly the same impact in the opposite direction. The impact on the group’s annual net finance expense of a 1% change in interest rates would have been a decrease of £130m (2017/18: £143m, 2016/17: £108m). Our exposure to foreign exchange volatility in the income statement, after hedging, (excluding translation exposures) would not have been material in 2018/19, 2017/18 and 2016/17. Credit ratings BT Group plc continues to target a BBB+/Baa1 credit rating over the cycle. We regularly review the liquidity of the group and our funding strategy takes account of medium-term requirements. These include the pension deficit and shareholder distributions. Our December 2030 bond contains covenants which require us to pay higher rates of interest since our credit ratings fell below A3 in the case of Moody’s or A– in the case of Standard & Poor’s (S&P). Additional interest of 0.25% per year accrues for each ratings category downgrade by each agency below those levels effective from the next coupon date following a downgrade. Based on the total notional value of debt outstanding of £2.0bn at 31 March 2019, our finance expense would increase/decrease by approximately £10m a year if the group’s credit rating were to be downgraded/upgraded, respectively, by one credit rating category by both agencies. BT Group plc’s credit ratings were as detailed below: 2019 2018 2017 At 31 March Rating Outlook Rating Outlook Rating Outlook Rating agency Moody’s Baa2 Stable Baa2 Stable Baa1 Negative Standard & Poor’s BBB Stable BBB+ Negative BBB+ Negative How do we manage liquidity risk? Management policy We maintain liquidity by entering into short and long-term financial instruments to support operational and other funding requirements, determined using short and long-term cash forecasts. These forecasts are supplemented by a financial headroom analysis which is used to assess funding adequacy for at least a 12-month period. On at least an annual basis the BT Group plc Board reviews and approves the long-term funding requirements of the group and on an ongoing basis considers any related matters. We manage refinancing risk by limiting the amount of borrowing that matures within any specified period and having appropriate strategies in place to manage refinancing needs as they arise. The maturity profile of our loans and borrowings at 31 March 2019 is disclosed in note 23. We have term debt maturities of £1.2bn in 2019/20. Our treasury operation reviews and manages our short-term requirements within the parameters of the policies set by the BT Group plc Board. We hold cash, cash equivalents and current investments in order to manage short-term liquidity requirements. At 31 March 2019 we had undrawn committed borrowing facilities of £2.1bn (2017/18: £2.1bn, 2016/17: £2.1bn) maturing in September 2021. In the UK, the group has arranged for funders to offer a supplier financing scheme to the group’s suppliers. This enables suppliers who sign up to the arrangements to sell their invoices to the funders and to be paid earlier than the invoice due date. The group assesses the arrangement against indicators to assess if debts which vendors have sold to the funder under the supplier financing scheme continue to meet the requirement to be disclosed as trade payables or should be classified as borrowings. At 31 March 2019 the payables met the criteria of trade payables. Maturity analysis The following table provides an analysis of the remaining contractually-agreed cash flows including interest payable for our non- derivative financial liabilities on an undiscounted basis, which therefore differs from both the carrying value and fair value. Non-derivative financial liabilities At 31 March 2019 Loans and other borrowings £m Interest on loans and other borrowings £m Trade and other payables £m Provisions £m Total £m Due within one year 2,883 584 5,195 39 8,701 Between one and two years 1,309 528 – 33 1,870 Between two and three years 15 520 – 35 570 Between three and four years 1,463 519 – 14 1,996 Between four and five years 964 505 – 12 1,481 After five years 12,036 4,345 – 127 16,508 18,670 7,001 5,195 260 31,126 Interest payments not yet accrued – (6,744 ) – – (6,744 ) Fair value adjustment 50 – – – 50 Impact of discounting – – – (29 ) (29 ) Carrying value on the balance sheet ab 18,720 257 5,195 231 24,403 Non-derivative financial liabilities At 31 March 2018 Loans and other borrowings £m Interest on loans and other borrowings £m Trade and other payables £m Provisions £m Total £m Due within one year 2,120 468 4,961 54 7,603 Between one and two years 1,192 421 – 34 1,647 Between two and three years 1,332 381 – 25 1,738 Between three and four years 18 374 – 43 435 Between four and five years 1,489 372 – 19 1,880 After five years 8,943 3,300 – 197 12,440 15,094 5,316 4,961 372 25,743 Interest payments not yet accrued – (5,147 ) – – (5,147 ) Fair value adjustment 73 – – – 73 Impact of discounting – – – (72 ) (72 ) Carrying value on the balance sheet ab 15,167 169 4,961 300 20,597 Non-derivative financial liabilities At 31 March 2017 Loans and other borrowings £m Interest on loans and other borrowings £m Trade and other payables £m Provisions £m Total £m Due within one year 2,602 532 5,298 62 8,494 Between one and two years 1,614 415 – 41 2,070 Between two and three years 1,166 364 – 21 1,551 Between three and four years 1,295 327 – 18 1,640 Between four and five years 12 319 – 17 348 After five years 6,868 2,726 – 310 9,904 13,557 4,683 5,298 469 24,007 Interest payments not yet accrued – (4,494 ) – – (4,494 ) Fair value adjustment 150 – – – 150 Impact of discounting – – – (177 ) (177 ) Carrying value on the balance sheet ab 13,707 189 5,298 292 19,486 a Foreign currency-related cash flows were translated at closing rates as at the relevant reporting date. Future variable interest rate cash flows were calculated using the most recent rate applied at the relevant balance sheet date. b The carrying amount of trade receivables and other payables excludes £1,479m (2017/18: £1,326m, 2016/17: £1,298m) of non-current trade and other payables and £632m (2017/18: £2,229m, 2016/17: £2,178m) of other taxation and social security and deferred income. Trade and other payables are held at amortised cost. The carrying amount of these balances approximates to fair value due to the short maturity of amounts payable. The following table provides an analysis of the contractually agreed cash flows in respect of the group’s derivative financial instruments. Cash flows are presented on a net or gross basis in accordance with the settlement arrangements of the instruments. Derivatives – Analysed by earliest payment date a Derivatives – Analysed based on holding instrument to maturity Derivative financial liabilities At 31 March 2019 Net settled £m Gross settled outflows £m Gross settled inflows £m Total £m Net settled £m Gross settled outflows £m Gross settled inflows £m Total £m Due within one year 167 1,007 (950 ) 224 82 1,007 (950 ) 139 Between one and two years 128 541 (489 ) 180 77 541 (489 ) 129 Between two and three years 131 131 (96 ) 166 71 131 (96 ) 106 Between three and four years 163 633 (591 ) 205 71 633 (591 ) 113 Between four and five years 207 1,095 (1,042 ) 260 71 1,095 (1,042 ) 124 After five years 43 3,790 (3,660 ) 173 467 3,790 (3,660 ) 597 Total b 839 7,197 (6,828 ) 1,208 839 7,197 (6,828 ) 1,208 Derivatives – Analysed by earliest payment date a Derivatives – Analysed based on holding instrument to maturity Derivative financial liabilities At 31 March 2018 Net settled £m Gross settled outflows £m Gross settled inflows £m Total £m Net settled £m Gross settled outflows £m Gross settled inflows £m Total £m Due within one year 140 587 (547 ) 180 91 587 (547 ) 131 Between one and two years 135 183 (166 ) 152 91 183 (166 ) 108 Between two and three years 156 442 (446 ) 152 85 69 (47 ) 107 Between three and four years 143 52 (29 ) 166 80 68 (47 ) 101 Between four and five years 161 52 (29 ) 184 80 68 (47 ) 101 After five years 291 2,234 (2,149 ) 376 599 2,575 (2,512 ) 662 Total b 1,026 3,550 (3,366 ) 1,210 1,026 3,550 (3,366 ) 1,210 Derivatives – Analysed by earliest payment date a Derivatives – Analysed based on holding instrument to maturity Derivative financial liabilities At 31 March 2017 Net settled £m Gross settled outflows £m Gross settled inflows £m Total £m Net settled £m Gross settled outflows £m Gross settled inflows £m Total £m Due within one year 291 582 (576 ) 297 92 582 (576 ) 98 Between one and two years 296 1,139 (1,097 ) 338 92 1,139 (1,097 ) 134 Between two and three years 198 — — 198 92 — — 92 Between three and four years 114 — — 114 88 — — 88 Between four and five years 104 — — 104 83 — — 83 After five years 123 — — 123 679 — — 679 Total b 1,126 1,721 (1,673 ) 1,174 1,126 1,721 (1,673 ) 1,174 a Certain derivative financial instruments contain break clauses whereby either the group or bank counterparty can terminate the swap on certain dates and the mark to market position is settled in cash. b How do we manage credit risk? Management policy Our exposure to credit risk arises from financial assets transacted by the treasury operation (primarily derivatives, investments, cash and cash equivalents) and from trading-related receivables. For treasury-related balances, the BT Group plc Board’s defined policy restricts exposure to any one counterparty by setting credit limits based on the credit quality as defined by Moody’s and Standard and Poor’s. The minimum credit ratings permitted with counterparties in respect of new transactions are A3/A– for long-term and P1/A1 for short-term investments. If counterparties in respect of existing transactions fall below the permitted criteria we will take action where appropriate. The treasury operation continuously reviews the limits applied to counterparties and will adjust the limit according to the nature and credit standing of the counterparty, and in response to market conditions, up to the maximum allowable limit set by the BT Group plc Board. Operational management policy Our credit policy for trading-related financial assets is applied and managed by each of the customer-facing units to ensure compliance. The policy requires that the creditworthiness and financial strength of customers are assessed at inception and on an ongoing basis. Payment terms are set in accordance with industry standards. Where appropriate, we may minimise risks by requesting securities such as deposits, guarantees and letters of credit. We take proactive steps including constantly reviewing credit ratings of counterparties to minimise the impact of adverse market conditions on trading-related financial assets. Exposures The maximum credit risk exposure of the group’s financial assets at the balance sheet date is as follows: At 31 March Notes 2019 £m 2018 £m 2017 £m Derivative financial assets 1,592 1,509 2,246 Investments 21 17,005 16,578 13,346 Trade and other receivables c 16 1,782 2,533 2,754 Contract assets 6 1,602 — — Cash and cash equivalents 22 1,664 521 526 23,645 21,141 18,872 c The carrying amount excludes £445m (2017/18: £317m, 2016/17: £360m) of non-current trade and other receivables which relate to non-financial assets, and £1,456m (2017/18: £1,496m, 2016/17: £1,106m) of prepayments, deferred contract costs and other receivables. The credit quality and credit concentration of cash equivalents, current asset investments and derivative financial assets are detailed in the tables below. Where the opinion of Moody’s and S&P differ, the lower rating is used. Moody’s/S&P credit rating of counterparty 2019 £m 2018 £m 2017 £m Aa2/AA and above 2,522 2,575 1,444 Aa3/AA– 1,376 313 208 A1/A+ a 1,145 651 952 A2/A a 649 628 370 A3/A– a 50 180 204 Baa1/BBB+ a 75 59 561 Baa2/BBB and below a 160 207 86 5,977 4,613 3,825 a We hold cash collateral of £638m (2017/18: £492m, 2016/17: £702m) in respect of derivative financial assets with certain counterparties. The concentration of credit risk for our trading balances is provided in note 16, which analyses outstanding balances by customer-facing unit. Where multiple transactions are undertaken with a single financial counterparty or group of related counterparties, we enter into netting arrangements to reduce our exposure to credit risk by making use of standard International Swaps and Derivatives Association (ISDA) documentation. We have also entered into credit support agreements with certain swap counterparties whereby, on a daily, weekly and monthly basis, the fair value position on notional £3,289m of long dated cross-currency swaps and interest rate swaps is collateralised. The related net cash inflow during the year was £129m (2016/17: outflow £220m, 2015/16: inflow £100m). The collateral paid and received is recognised within current asset investments and loans and other borrowings, respectively. Offsetting of financial instruments The table below shows our financial assets and liabilities that are subject to offset in the group’s balance sheet and the impact of enforceable master netting or similar agreements. Related amounts not set off in the balance sheet Financial assets and liabilities At 31 March 2019 Amounts presented in the balance sheet £m Right of set off with derivative counterparties £m Cash collateral £m Net amount £m Derivative financial assets 1,592 (802 ) (638 ) 152 Derivative financial liabilities (940 ) 802 90 (48 ) Total 652 – (548 ) 104 Related amounts not set off in the balance sheet Financial assets and liabilities At 31 March 2018 Amounts presented in the balance sheet £m Right of set off with derivative counterparties £m Cash collateral £m Net amount £m Derivative financial assets 1,509 (754 ) (492 ) 263 Derivative financial liabilities (837 ) 754 60 (23 ) Total 672 – (432 ) 240 Related amounts not set off in the balance sheet Financial assets and liabilities At 31 March 2017 Amounts presented in the balance sheet £m Right of set off with derivative counterparties £m Cash collateral £m Net amount £m Derivative financial assets 2,246 (693 ) (702 ) 851 Derivative financial liabilities (903 ) 693 64 (146 ) Total 1,343 – (638 ) 705 Derivatives and hedging We use derivative financial instruments mainly to reduce exposure to foreign exchange and interest rate risks. Derivatives may qualify as hedges for accounting purposes if they meet the criteria for designation as fair value hedges or cash flow hedges in accordance with IFRS 9. Significant accounting policies that apply to derivatives and hedge accounting All of our derivative financial instruments are held at fair value on the balance sheet. Derivatives designated in a cash flow hedge The group designates certain derivatives as cash flow hedges. Where derivatives qualify for hedge accounting, recognition of any resultant gain or loss depends on the nature of the hedge. The group designates certain derivatives as cash flow hedges. To qualify for hedge accounting, hedge documentation must be prepared at inception, the hedge must be in line with BT’s risk management strategy and there must be an economic relationship based on currency, amount and timing of the respective cashflows of the hedged item and the hedging instrument. This is assessed at inception and in subsequent periods in which the hedge remains in operation. Hedge accounting is discontinued when it is no longer in line with BT Group’s risk management strategy or if it no longer qualifies for hedge accounting. When a derivative financial instrument is designated as a hedge of the variability in cash flows of a recognised asset or liability, or a highly probable transaction, the effective part of any gain or loss on the derivative financial instrument is recognised directly in equity, in the cash flow reserve. For cash flow hedges of recognised assets or liabilities, the associated cumulative gain or loss is removed from equity and recognised in the same line of the income statement and in the same period or periods that the hedged transaction affects the income statement. Any ineffectiveness arising on a cash flow hedge is recognised immediately in the income statement. Other derivatives Our policy is not to use derivatives for trading purposes. However, due to the complex nature of hedge accounting, some derivatives may not qualify for hedge accounting, or may be specifically not designated as a hedge because natural offset is more appropriate. These derivatives are classified as fair value through profit and loss and are recognised at fair value. Any direct transaction costs are recognised immediately in the income statement. Gains and losses on re-measurement are recognised in the income statement in the line that most appropriately reflects the nature of the item or transaction to which they relate. Derivative financial instruments are classified as current assets or current liabilities where they have a maturity period within 12 months. Where derivative financial instruments have a maturity period greater than 12 months, they are classified within either non-current assets or non-current liabilities. Where the fair value of a derivative contract at initial recognition is not supported by observable market data and differs from the transaction price, a day one gain or loss will arise which is not recognised in the income statement. Such gains and losses are deferred and amortised to the income statement based on the remaining contractual term and as observable market data becomes available. The fair values of outstanding swaps and foreign exchange contracts are estimated using discounted cash flow models and market rates of interest and foreign exchange at the balance sheet date. At 31 March 2019 Current asset £m Non-current asset £m Current liability £m Non-current liability £m Designated in a cash flow hedge 102 1,228 40 689 Other 9 253 8 203 Total derivatives 111 1,481 48 892 At 31 March 2018 Current asset £m Non-current asset £m Current liability £m Non-current liability £m Designated in a cash flow hedge 187 1,061 41 587 Other 10 251 9 200 Total derivatives 197 1,312 50 787 At 31 March 2017 Current asset £m Non-current asset £m Current liability £m Non-current liability £m Designated in a cash flow hedge 417 1,508 25 616 Other 11 310 9 253 Total derivatives 428 1,818 34 869 All derivative financial instruments are categorised at Level 2 of the fair value hierarchy as defined in note 21. Instruments designated in a cash flow hedge include interest rate swaps and cross-currency swaps hedging euro- and US dollar- denominated borrowings. Forward currency contracts are taken out to hedge step-up interest on currency denominated borrowings relating to the group’s 2030 US dollar bond. The hedged cash flows will affect the group’s income statement as interest and principal amounts are repaid over the remaining term of the borrowings (see note 23). We hedge forecast foreign currency purchases, principally denominated in US dollar, euro and Asia Pacific currencies 12 months forward with certain specific transactions hedged further forward. The related cash flows are recognised in the income statement over this period. The amounts related to items designated as hedging instruments were as follows: Hedged items At 31 March 2019 Notional principal £m Asset £m Liability £m Balance in cash flow hedge related reserves (gain)/loss £m Fair value (gain)/loss recognised in OCI £m Amount recycled from cash flow hedge related reserves to P&L £m Sterling, euro and US dollar denominated borrowings a 13,518 1,311 (702 ) (48 ) (130 ) (19 ) US dollar step up interest on US denominated borrowings b 145 3 (1 ) (38 ) (13 ) 4 Foreign currency purchases, principally denominated in US dollar, euro and Asia Pacific currencies c 1,821 16 (26 ) (13 ) (33 ) 33 Total cash flow hedges 15,484 1,330 (729 ) (99 ) (176 ) 18 Deferred tax – – 15 Derivatives not in a designated hedge relationship 262 (211 ) – Carrying value on the balance sheet 1,592 (940 ) (84 ) Hedged items At 31 March 2018 d Notional principal £m Asset £m Liability £m Balance in cash flow hedge related reserves (gain)/loss £m Fair value (gain)/loss recognised in OCI £m Amount recycled from cash flow hedge related reserves to P&L £m Sterling, euro and US dollar denominated borrowings a 12,504 1,222 (608 ) 101 347 (333 ) US dollar step up interest on US denominated borrowings b 143 – (6 ) (29 ) 13 3 Foreign currency purchases, principally denominated in US dollar, euro and Asia Pacific currencies c 1,989 26 (14 ) (13 ) 8 53 Total cash flow hedges 14,636 1,248 (628 ) 59 368 (277 ) Deferred tax – – (22 ) Derivatives not in a designated hedge relationship 261 (209 ) – Carrying value on the balance sheet 1,509 (837 ) 37 Hedged items At 31 March 2017 d Notional principal £m Asset £m Liability £m Balance in cash flow hedge related reserves (gain)/loss £m Fair value (gain)/loss recognised in OCI £m Amount recycled from cash flow hedge related reserves to P&L £m Sterling, euro and US dollar denominated borrowings a 10,041 1,845 (621 ) 87 (800 ) 938 US dollar step up interest on US denominated borrowings b 146 5 (2 ) (45 ) (21 ) 4 Foreign currency purchases, principally denominated in US dollar, euro and Asia Pacific currencies c 2,327 75 (18 ) (74 ) (63 ) (4 ) Total cash flow hedges 12,514 1,925 (641 ) (32 ) (884 ) 938 Deferred tax – – (95 ) Derivatives not in a designated hedge relationship 321 (262 ) – Carrying value on the balance sheet 2,246 (903 ) (127 ) a Sterling, euro and US dollar denominated borrowings are hedged using cross currency swaps and interest rate swaps. Amounts recycled to the profit and loss are presented within other operating costs and finance expense b US dollar step up interest on US denominated borrowings are hedged using forward currency contracts. Amounts recycled to profit and loss are presented within finance expense. c Foreign currency purchases, principally denominated in US dollar, euro and Asia Pacific currencies are hedged using forward currency contracts. Amounts recycled to profit and loss in respect of these items are presented within cost of sales and other operating costs. d We have presented comparatives to this information, now required by IFRS7 following the adoption of IFRS9, for 31 March 2018 and 31 March 2017. All cash flow hedges were effective in the period.

Other reserves

Other reserves	12 Months Ended
	Mar. 31, 2019
Disclosure Of Other Reserves [Abstract]
Other reserves	t Other comprehensive income Cash flow reserve a £m Fair value reserve b £m Cost of hedging reserve c £m Translation reserve d £m Merger and other reserves £m Total £m At 1 April 2016 173 16 – 345 858 1,392 Exchange differences e – – – 227 – 227 Net fair value gain on cash flow hedges 884 – – – – 884 Movements in relation to cash flow hedges recognised in income and expense (938 ) – – – – (938 ) Fair value movement on available-for-sale assets – (3 ) – – – (3 ) Tax recognised in other comprehensive income 8 – – 21 – 29 At 1 April 2017 127 13 – 593 858 1,591 Exchange differences e – – – (188 ) – (188 ) Net fair value gain on cash flow hedges (368 ) – – – – (368 ) Movements in relation to cash flow hedges recognised in income and expense 277 – – – – 277 Fair value movement on available-for-sale assets – 11 – – – 11 Tax recognised in other comprehensive income 10 – – (9 ) – 1 Transfer to realised profit (83 ) – – – – (83 ) At 31 March 2018 (37 ) 24 – 396 858 1,241 Transfer to cost of hedging reserve 81 – (81 ) – – – At 31 March 2018 44 24 (81 ) 396 858 1,241 Exchange differences e – – – 64 – 64 Net fair value loss on cash flow hedges 168 – 8 – – 176 Movements in relation to cash flow hedges recognised in income and expense (31 ) – 13 – – (18 ) Fair value movement on assets at fair value through other comprehensive income – 3 – – – 3 Tax recognised in other comprehensive income (37 ) – – (4 ) – (41 ) Transfer to realised profit – – – – – – At 31 March 2019 144 27 (60 ) 456 858 1,425 a The cash flow reserve is used to record the effective portion of the cumulative net change in the fair value of cash flow hedging instruments related to hedged transactions that have not yet occurred. Amounts ‘recognised in income and expense’ include a net charge to the cash flow reserve of £30m (2017/18: credit of £295m, 2016/17: charge of £941m) relating to fair value movements on derivatives. The items generating these foreign exchange movements are in designated cash flow hedge relationships. b The fair value reserve (2018, 2017: available-for-sale reserve) is used to record the cumulative fair value gains and losses on assets classified as fair value through other comprehensive income (2018, 2017: available-for-sale financial assets). The cumulative gains and losses are recycled to the income statement on disposal of the assets. c The cost of hedging reserve reflects the gain or loss on the portion excluded from the designated hedging instrument that relates to the currency basis element of our cross currency swaps. It is initially recognised in other comprehensive income and accounted for similarly to gains or losses in the cash flow reserve. d The translation reserve is used to record cumulative translation differences on the assets and liabilities of foreign operations. The cumulative translation differences are recycled to the income statement on disposal of the foreign operation. e Excludes £(2)m (2017/18: £1m, 2016/17: £10m) of exchange differences in relation to retained earnings attributed to non-controlling interests .

Directors emoluments and pensio

Directors emoluments and pensions	12 Months Ended
	Mar. 31, 2019
Disclosure Of Defined Benefit Plans [Abstract]
Directors emoluments and pensions	The directors at 31 March 2019 were Simon Lowth and Neil Harris who served throughout 2018/19 and Ulrica Fearn, who was appointed on 1 June 2018. Patrick Bradley served as a director until 31 August 2018 and Glyn Parry served as a director until 12 December 2018. For the year ended 31 March 2019 the aggregate emoluments of the directors excluding deferred bonuses of £451,000 (2017/18: £319,000) was £2,973,000 (2017/18: £2,525,000). Deferred bonuses are payable in 5p ordinary shares of BT Group plc in three years’ time subject to continuous employment. Retirement benefits were accruing to no directors (2017/18: n During the year no director exercised options (2017/18: none) under BT Group share option plans. Five directors who held office for the whole or part of the year (2017/18: six) received or are entitled to receive 5p ordinary shares of BT Group plc under BT long-term incentive plans. The aggregate value of BT Group plc shares which vested to directors during the year under BT long-term incentive plans was £35,000 (2017/18: £179,000). The emoluments of the highest paid director excluding his deferred bonus of £327,000 (2017/18: £302,400) were £1,606,000 (2017/18: £1,538,000). He is entitled to receive 3,148,023 BT Group plc 5p ordinary shares under BT long-term incentive plans subject to continuous employment and in some cases to certain performance conditions being met. Included in the above aggregate emoluments are those of Simon Lowth who is also a director of the ultimate holding company, BT Group plc. The directors do not believe it is practicable for the purposes of this report to apportion the amount of total emoluments received by him between his services as director of the company and his services as director of BT Group plc. The emoluments of the directors are calculated in accordance with the statutory provisions applicable to the company.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Mar. 31, 2019
Disclosure Of Transactions Between Related Parties [Abstract]
Related Party Transactions	t e i Key management personnel comprise executive and non-executive directors and members of the BT Group plc Executive Committee . Amounts paid to the group’s retirement benefit plans are set out in note 19. British Telecommunications plc and certain of its subsidiaries act as a funder and deposit taker for cash related transactions for both its parent and ultimate parent company. The loan arrangements described below with these companies reflect this. Cash transactions usually arise where the parent and ultimate parent company are required to meet their external payment obligations or receive amounts from third parties. These principally relate to the payment of dividends, the buyback of shares, the exercise of share options and the issuance of ordinary shares. Transactions between the ultimate parent company, parent company and the group are settled on both a cash and non-cash basis through these loan accounts depending on the nature of the transaction. In 2001/02 the group demerged its former mobile phone business and as a result BT Group plc became the listed ultimate parent company of the remaining group. The demerger steps resulted in the formation of an intermediary holding company, BT Group Investments Limited, between BT Group plc and British Telecommunications plc. This intermediary company held an investment of £18.5bn in British Telecommunications plc which was funded by an intercompany loan facility with British Telecommunications plc. A dividend of £2,500m (2017/18: £nil) was settled on 22 May 2018 with the parent company in relation to the year ended 31 March 2018. A dividend of £1,575m has been declared in relation to the year ended 31 March 2019. This was declared after 31 March 2019 so no liability (amount owed to parent company) is recorded in these financial statements. See note 12 and the group statement of changes in equity. The loan facilities with both the parent company and ultimate parent company accrue interest at a rate of LIBOR plus 102.5 basis points, and are subject to an overall maximum of £35bn and £10bn respectively. The parent company currently finances its obligations on the loan as they fall due through dividends paid by the company. In 2015/16 the ultimate parent company of the group raised £1.0bn from an equity placing and entered into an additional intercompany loan agreement with British Telecommunications plc for this amount. This amount was raised to support BT Group plc’s planned acquisition of EE. A summary of the balances with the parent and ultimate parent companies and the finance income or expense arising in respect of these balances is set out below: 2019 2018 2017 Notes Asset (liability) at 31 March £m Finance income (expense) £m Asset (liability) at 31 March £m Finance income (expense) £m Asset (liability) at 31 March £m Finance income (expense) £m Amounts owed by (to) parent company Loan facility – non-current assets investments 21,24 10,436 211 10,318 169 10,191 191 Loan facility – current asset investments 21 211 n/a 168 n/a 192 n/a Trade and other payables 17 (55 ) n/a (50 ) n/a (63 ) n/a Amounts owed by (to) ultimate parent company a Non-current assets investments 21,24 3,029 61 2,983 34 1,371 28 Non-current liabilities loans 23 (1,061 ) (43 ) (1,044 ) (18 ) (1,024 ) (25 ) Trade and other receivables 16 16 n/a 15 n/a 25 n/a Trade and other payables 17 (1 ) n/a – n/a – n/a Current asset investments 21 61 n/a 34 n/a 28 n/a Current liabilities loans 23 (1,040 ) n/a (18 ) n/a (159 ) n/a a During the year we made cash payments of £ 1,514 m to BT Group plc offset by the receipt of £ 6 m from BT Group plc resulting in net cash outflow of £ 1,508 m. In addition there are non cash movements of £41m on non-current asset investments relating to interest on loans, employee share schemes and tax settlements made by BT plc on behalf of BT Group plc

Financial commitments and conti

Financial commitments and contingent liabilities	12 Months Ended
	Mar. 31, 2019
Financial Commitments [Abstract]
Financial commitments and contingent liabilities	Financial commitments were as follows: At 31 March 2019 £m 2018 £m Operating lease commitments 6,619 6,597 TV programme rights commitments 2,113 2,823 Capital commitments 1,432 993 Other commitments 253 624 Total 10,417 11,037 TV programme rights commitments, mainly relating to football broadcast rights, are those for which the licence period has not yet started. Future minimum operating lease payments were as follows: Payable in the year ending 31 March: 2019 £m 2018 £m 2019 – 600 2020 755 550 2021 641 513 2022 599 486 2023 555 463 2024 512 449 Thereafter 3,557 3,536 Total future minimum operating lease payments 6,619 6,597 O p n e o i t e a n p l i i n g w h a a n p a t i e e b a n a 2 0 0 1 L e a a a ag t e a 2 17/ 8 e n n a l f i e o a e g ea 2 17/ 8 14 Oth e a i o e o e e o g e n i b i i u n e a 0 h e h o i i t h Commitments and guarantees BDUK Under the Broadband Delivery UK programme, grants received by the group may be subject to reinvestment or repayment to the customer depending on the level of take-up. Te l e ó e s W e p d g u a n e a e a e e e n t e e n e e ó i e o e th d e e o o 1 e e 2 1 l n p a o e l e n p e ua n e h r n e o h e n o e d e a e e m u t e d e f e a u u e o b g a n h g u a n e n i e ó U L e a d a e i t o b i o Legal The group is involved in various legal proceedings, including actual or threatened litigation, and government or regulatory investigations. However, save as disclosed below, the group does not currently believe that there are any legal proceedings, or government or regulatory investigations that may have a material adverse impact on the operations or financial condition of the group. In respect of each of the claims below, the nature and progression of such proceedings and investigations can make it difficult to predict the impact they will have on the group. There are many reasons why we cannot make these assessments with certainty, including, among others, that they are in early stages, no damages or remedies have been specified, and/or the often slow pace of litigation. It a l u US securities class action complaints: The plaintiffs filed a third amended complaint in December 2018. We filed a motion to dismiss that complaint, which plaintiffs opposed. We filed our reply to the plaintiff’s opposition to the motion to dismiss on 11 January 2019. We are awaiting a decision from the US District court. Italian Authorities: On 11 February 2019 the Milan Public Prosecutor served BT Italia S.P.A. with a notice regarding conclusion of their preliminary investigation. The notice (which named BT Italia, as well as various individuals) records the prosecutor’s view that as at the conclusion of the preliminary investigation there is a basis for proceeding with its case against BT Italia for certain potential offences under articles 5 and 25 of Legislative Decree 231/2001. BT Italia disputes this and maintains in a defence brief filed on 19 April 2019 that it should not be prosecuted. BT Italia is not presently the subject of any formal charge (nor are any of the individuals named in the prosecutor’s notice). Phones 4U In December 2016, the administrators of Phones 4U started legal proceedings in the High Court in the United Kingdom against EE, claiming payments under a retail trading agreement for sums then due in respect of revenues (net of costs) from certain customers prior to Phones 4U entering administration. This sharing of revenue under the retail trading agreement was due to continue until September 2019, with related payments continuing until April 2021. On May 2018 we reached a confidential agreement with the administrators of Phones 4U to settle this matter. This settlement is in line with the accruals we held to cover potential payments required by EE. Since 2015 the administrators of Phones 4U Limited have made allegations that EE and other mobile network operators colluded to procure Phones 4U’s insolvency. During the year proceedings were issued for an unquantified amount by the administrators and in April 2019 we submitted our defence to this claim. We continue to dispute these allegations vigorously. Brazilian tax claims The Brazilian state tax authorities have made tax demands on the exchange of goods and services (ICMS) and regulatory assessments (FUST/FUNTTEL) against certain Brazilian subsidiaries. These are indirect taxes imposed on the provision of telecommunications services in Brazil. The state tax and regulatory authorities are seeking to impose ICMS and FUST/FUNTTEL on revenue earned on activities that the company does not consider as being part of the provision of telecommunications services, such as equipment rental and managed services. We have disputed the basis on which ICMS and FUST/FUNTTEL are imposed and, in the case of ICMS, have challenged the rate which the tax authorities are seeking to apply. We currently have 33 ICMS cases with a current potential value of £204m (as at the end of March 2019). This is the assessed amount for all cases spanning the period from 1998 to 2012 (plus one outlier case for the period 2013 to 2016 in the state of Minas Gerais and one case for the period 2014 to 2015 in the state of Amazonas). There are currently 56 FUST/FUNTTEL cases with a known overall liability of £19m; with a further £4m estimated (as at the end of April 2019). The judicial process is likely to take many years. There are eight ICMS cases worth approximately £55m which are at an advanced stage. These are currently pending before the Sao Paulo Court of Appeal. We are waiting for the Reporting Judge to schedule the trial hearing and expect to have a date soon, following the February judicial recess. Regulatory matters In respect of regulatory risks, the group provides for anticipated costs where an outflow outcome Northern Ireland Public Sector Shared Network contract On 4 April 2019 Ofcom opened an investigation into whether the award of the Public Sector Shared Network contract for Northern Ireland to BT complied with relevant significant market power conditions. We are cooperating with Ofcom’s investigation. Other regulatory matters We hold provisions reflecting management’s estimates of regulatory risks across a range of issues, including price and service issues. The precise outcome of each matter depends on whether it becomes an active issue, and the extent to which negotiation or regulatory decisions will result in financial settlement .

Post Balance Sheet Events

Post Balance Sheet Events	12 Months Ended
	Mar. 31, 2019
Disclosure Of Nonadjusting Events After Reporting Period [Abstract]
Post Balance Sheet Events	Spectrum Annual Licence Fee restitution claim Annual fees for 1800MHz spectrum have increased from 31 January 2019 following Ofcom’s final statement and introduction of new fees regulations in December 2018. The Group has sought, through legal proceedings, repayment of overpaid fees that were charged during the period 2015-2017 under the previous 2015 fees regulations that were quashed by the Court of Appeal in 2017. On 17 May 2019, the Commercial Court handed down its judgment in the favour of the Group and the Group received a payment of £87m on 21 May 2019. Ofcom has obtained permission to appeal the judgment to the Court of Appeal, the appeal will likely be heard in late 2020.

Significant accounting polici_2

Significant accounting policies that apply to the overall financial statements (Policies)	12 Months Ended
	Mar. 31, 2019
Significant Accounting Policies [Abstract]
Basis of consolidation	Basis of consolidation The group financial statements consolidate the financial statements of British Telecommunications plc and its subsidiaries, and include its share of the results of associates and joint ventures using the equity method of accounting. The group recognises its direct rights to (and its share of) jointly held assets, liabilities, revenues and expenses of joint operations under the appropriate headings in the consolidated financial statements. All business combinations are accounted for using the acquisition method regardless of whether equity instruments or other assets are acquired. No material acquisitions were made in the year. A subsidiary is an entity that is controlled by another entity, known as the parent or investor. An investor controls an investee when the investor is exposed, or has rights, to variable returns from its involvement with the investee and has the ability to affect those returns through its power over the investee. Non-controlling interests in the net assets of consolidated subsidiaries, which consist of the amounts of those interests at the date of the original business combination and non-controlling share of changes in equity since the date of the combination, are not material to the group’s financial statements. The results of subsidiaries acquired or disposed of during the year are consolidated from and up to the date of change of control. Where necessary, accounting policies of subsidiaries have been aligned with the policies adopted by the group. All intra-group transactions including any gains or losses, balances, income or expenses are eliminated in full on consolidation. When the group loses control of a subsidiary, the profit or loss on disposal is calculated as the difference between (i) the aggregate of the fair value of the consideration received and the fair value of any retained interest and (ii) the previous carrying amount of the assets (including goodwill), and liabilities of the subsidiary and any non-controlling interests. The profit or loss on disposal is recognised as a specific item.
Inventories	Inventories Network maintenance equipment and equipment to be sold to customers are stated at the lower of cost or net realisable value, taking into account expected revenue from the sale of packages comprising a mobile handset and a subscription. Cost corresponds to purchase or production cost determined by either the first in first out (FIFO) or average cost method.
Government grants	Government grants Government grants are recognised when there is reasonable assurance that the conditions associated with the grants have been complied with and the grants will be received. Grants for the purchase or production of property, plant and equipment are deducted from the cost of the related assets and reduce future depreciation expense accordingly. Grants for the reimbursement of operating expenditure are deducted from the related category of costs in the income statement. Estimates and judgements applied in accounting for government grants received in respect of the BDUK programme and other rural superfast broadband contracts are described in note 14. Once a government grant is recognised, any related deferred income is treated in accordance with IAS 20 ‘Accounting for Government Grants and Disclosure of Government Assistance’.
Foreign currencies	Foreign currencies Foreign currency transactions are translated into the functional currency using the exchange rates prevailing at the date of the transaction. Foreign exchange gains and losses resulting from the settlement of transactions and the translation of monetary assets and liabilities denominated in foreign currencies at period end exchange rates are recognised in the income statement line which most appropriately reflects the nature of the item or transaction. On consolidation, assets and liabilities of foreign undertakings are translated into sterling at year end exchange rates. The results of foreign undertakings are translated into sterling at average rates of exchange for the year (unless this average is not a reasonable approximation of the cumulative effects of the rates prevailing on the transaction dates, in which case income and expenses are translated at the dates of the transactions). Foreign exchange differences arising on the retranslation of foreign undertakings are recognised directly in a separate component of equity, the translation reserve. In the event of the disposal of an undertaking with assets and liabilities denominated in a foreign currency, the cumulative translation difference associated with the undertaking in the translation reserve is charged or credited to the gain or loss on disposal recognised in the income statement.
Research and development	Research and development Research expenditure is recognised in the income statement in the period in which it is incurred. Development expenditure, including the cost of internally developed software, is recognised in the income statement in the period in which it is incurred unless it is probable that economic benefits will flow to the group from the asset being developed, the cost of the asset can be reliably measured and technical feasibility can be demonstrated, in which case it is capitalised as an intangible asset on the balance sheet. Capitalisation ceases when the asset being developed is ready for use. Research and development costs include direct and indirect labour, materials and directly attributable overheads.
Leases	Leases Under IAS 17, the determination of whether an arrangement is, or contains, a lease is based on the substance of the arrangement and requires an assessment of whether the fulfilment of the arrangement is dependent on the use of a specific asset or assets and whether the arrangement conveys the right to use the asset. Leases of property, plant and equipment where we hold substantially all the risks and rewards of ownership are classified as finance leases. Finance lease assets are capitalised at the commencement of the lease term at the lower of the present value of the minimum lease payments or the fair value of the leased asset. The obligations relating to finance leases, net of finance charges in respect of future periods, are recognised as liabilities. Leases are subsequently measured at amortised cost using the effective interest method. Leases where a significant portion of the risks and rewards are held by the lessor are classified as operating leases. Rentals are charged to the income statement on a straight line basis over the period of the lease.
Termination benefits	Termination benefits Termination benefits (leaver costs) are payable when employment is terminated before the normal retirement date, or when an employee accepts voluntary redundancy in exchange for these benefits. We recognise termination benefits when they are demonstrably committed to the affected employees leaving the group.
Significant accounting policies relating to revenue recognition	Significant accounting policies that apply to revenue On inception of the contract we identify a “performance obligation” for each of the distinct goods or services we have promised to provide to the customer. The consideration specified in the contract with the customer is allocated to each performance obligation identified based on their relative standalone selling prices, and is recognised as revenue as they are satisfied. The table below summarises the performance obligations we have identified for our major service lines and provides information on the timing of when they are satisfied and the related revenue recognition policy. Also detailed in this note is revenue expected to be recognised in future periods for contracts in place at 31 March 2019 that contain unsatisfied performance obligations. Service line Performance obligations Revenue recognition policy ICT and managed networks Provision of networked IT services, managed network services, and arrangements to design and build software solutions. Performance obligations are identified for each distinct service or deliverable for which the customer has contracted, and are considered to be satisfied over the time period that we deliver these services or deliverables. Commitments to provide hardware to customers that are distinct from the other promises are considered to be satisfied at the point in time that control passes to the customer. Revenue for services is recognised over time using a measure of progress that appropriately reflects the pattern by which the performance obligation is satisfied. For time and material contracts, revenue is recognised as the service is received by the customer. Where performance obligations exist for the provision of hardware, revenue is recognised at the point in time that the customer obtains control of the promised asset. long-term fixed price contracts revenue recognition will typically be based on the achievement of contract milestones and customer acceptance. Fixed access subscriptions Provision of broadband, TV and fixed telephony services including local, national and international calls, connections, line rental, and calling features. Performance obligations exist for each ongoing service provided to the customer and are satisfied over the period that the services are provided. Installation services are recognised as distinct performance obligations if their relationship with the other services in the contract is purely functional. These are satisfied when the customer benefits from the service. Connection services are not distinct performance obligations and are therefore combined with the associated service performance obligation. Fixed subscription charges are recognised as revenue on a straight line basis over the period that the services are provided. Upfront charges for non-distinct connection and installation services are deferred as contract liabilities and are recognised as revenue over the same period. Variable charges such as call charges are recognised when the related services are delivered. Where installation activities are distinct performance obligations, revenue is recognised at the point in time that the installation is completed. Mobile subscriptions Provision of mobile postpaid and prepaid services, including voice minutes, SMS, and data services. Performance obligations exist for each ongoing service provided to the customer and are satisfied over the period that the services are provided. Subscription fees, consisting primarily of monthly charges for access to broadband and other internet access or voice and data services, are recognised as the service is provided. One-off services such as calls outside of plan and excess data usage are recognised when the service is used. Equipment and other services Provision of equipment and other services, including mobile phone handsets and hardware such as set top boxes and broadband routers provided as part of customer contracts. Performance obligations are satisfied at the point in time that control passes to the customer. For other services, performance obligations are identified based on the distinct goods and services we have committed to provide. Revenue from equipment sales is recognised at the point in time that control passes to the customer. Where payment is not received in full at the time of the sale, such as with equipment provided as part of mobile and fixed access subscriptions, contract assets are recognised for the amount due from the customer that will be recovered over the contract period. Revenue to be recognised is We recognise revenue based on the relative standalone selling price of each performance obligation. Determining the standalone selling price often requires judgement and may be derived from regulated prices, list prices, a cost-plus derived price, or the price of similar products when sold on a standalone basis by BT or a competitor. In some cases it may be appropriate to use the contract price when this represents a bespoke price that would be the same for a similar customer in a similar circumstance. The fixed element of fixed access and mobile subscription arrangements sold by our Consumer business is typically payable in advance, with any variable or one-off charges billed in arrears. Payment is received immediately for direct sales of equipment to customers. Where equipment is provided to customers under mobile and fixed access subscription arrangements, payment for the equipment is received over the course of the contract term. For sales by our enterprise businesses, invoices are issued in line with contractual terms. Payments received in advance are recognised as contract liabilities, amounts billed in arrears are recognised as contract assets. We do not have any material obligations in respect of returns, refunds or warranties. Where we act as an agent in a transaction, we recognise commission net of directly attributable costs. Where the actual and estimated costs to completion of the contract exceed the estimated revenue, a loss is recognised immediately. We exercise judgement in assessing whether the initial set-up, transition and transformation phases of long-term contracts are distinct from the other services to be delivered under the contract and therefore represent distinct performance obligations. This determines whether revenue is recognised in the early stages of the contract, or deferred until delivery of the other services promised in the contract begins. We recognise immediately the entire estimated loss for a contract when we have evidence that the contract is unprofitable. If these estimates indicate that any contract will be less profitable than previously forecast, contract assets may have to be written down to the extent they are no longer considered to be fully recoverable. We perform ongoing profitability reviews of our contracts in order to determine whether the latest estimates are appropriate. Key factors reviewed include: - Transaction volumes or other inputs affecting future revenues which can vary depending on customer requirements, plans, market position and other factors such as general economic conditions. - Our ability to achieve key contract milestones connected with the transition, development, transformation and deployment phases for customer contracts. - The status of commercial relations with customers and the implications for future revenue and cost projections. - Our estimates of future staff and third-party costs and the degree to which cost savings and efficiencies are deliverable.
Significant accounting policies that apply to property, plant and equipment	Significant accounting policies that apply to property, plant and equipment Our property, plant and equipment is included at historical cost, net of accumulated depreciation, government grants and any impairment charges. Property, plant and equipment acquired through business combinations are initially recorded at fair value and subsequently accounted for on the same basis as our existing assets. We derecognise items of property, plant and equipment on disposal or when no future economic benefits are expected to arise from the continued use of the asset. The difference between the sale proceeds and the net book value at the date of disposal is recognised in operating costs in the income statement. Included within the cost of network infrastructure and equipment are direct and indirect labour costs, materials and directly attributable overheads. We depreciate property, plant and equipment on a straight line basis from the time the asset is available for use, to write off the asset’s cost over the estimated useful life taking into account any expected residual value. Freehold land is not depreciated. Estimated useful economic lives The estimated useful lives assigned to principal categories of assets are as follows: Land and buildings – Freehold buildings 14 to 50 years – Short-term leasehold improvements Shorter of 10 years or lease term – Leasehold land and buildings Unexpired portion of lease or 4 0 years, whichever is the shorter Network infrastructure Transmission equipment – Duct 40 years – Cable 3 to 25 years – Fibre 5 to 20 years Exchange equipment 2 to 13 years Other network equipment 2 to 20 years Other assets – Motor vehicles 2 to 9 years – Computers and office equipment 3 to 7 years Assets held under finance leases are depreciated over the shorter of the lease term or their useful economic life. Residual values and useful lives are reassessed annually and, if necessary, changes are recognised prospectively.
Significant accounting policies relating to trade and other receivables	Significant accounting policies that apply to trade and other receivables We initially recognise trade and other receivables at fair value, which is usually the original invoiced amount. They are subsequently carried at amortised cost using the effective interest method. The carrying amount of these balances approximates to fair value due to the short maturity of amounts receivable. We provide services to consumer and business customers, mainly on credit terms. We know that certain debts due to us will not be paid through the default of a small number of our customers. Because of this, we recognise an allowance for doubtful debts on initial recognition of receivables, which is deducted from the gross carrying amount of the receivable. The allowance is calculated by reference to credit losses expected to be incurred over the lifetime of the receivable. In estimating a loss allowance we consider historical experience and informed credit assessment alongside other factors such as the current state of the economy and particular industry issues. We consider reasonable and supportable information that is relevant and available without undue cost or effort. Once recognised, trade receivables are continuously monitored and updated. Allowances are based on our historical loss experiences for the relevant aged category as well as forward-looking information and general economic conditions. Allowances are calculated by individual customer-facing units in order to reflect the specific nature of the customers relevant to that customer-facing unit.
Significant accounting policies relating to deferred contract costs	Significant accounting policies that apply to deferred contract costs We capitalise certain costs associated with the acquisition and fulfilment of contracts with customers and amortise them over the period that we transfer the associated services. Connection costs are deferred as contract fulfilment costs because they allow satisfaction of the associated connection performance obligation and are considered recoverable. Sales commissions and other third party contract acquisition costs are capitalised as costs to acquire a contract unless the associated contract term is less than 12 months, in which case they are expensed as incurred. Capitalised costs are amortised over the minimum contract term. A portfolio approach is used to determine contract term. Where the initial set-up, transition and transformation phases of long-term contractual arrangements represent distinct performance obligations, costs in delivering these services are expensed as incurred. Where these services are not distinct performance obligations, we capitalise eligible costs as a cost of fulfilling the related service. Capitalised costs are amortised on a straight line basis over the remaining contract term, unless the pattern of service delivery indicates a more appropriate profile. To be eligible for capitalisation, costs must be directly attributable to specific contracts, relate to future activity, and generate future economic benefits. Capitalised costs are regularly assessed for recoverability.
Significant accounting policies that apply to trade and other payables	Significant accounting policies that apply to trade and other payables We initially recognise trade and other payables at fair value, which is usually the original invoiced amount. We subsequently carry them at amortised cost using the effective interest method.
Significant accounting policies that apply to provisions	Significant accounting policies that apply to provisions We recognise provisions when the group has a present legal or constructive obligation as a result of past events, it is probable that an outflow of resources will be required to settle the obligation and the amount can be reliably estimated. Provisions are determined by discounting the expected future cash flows at a pre-tax rate that reflects current market assessments of the time value of money and the risks specific to the liability. Financial liabilities within provisions are initially recognised at fair value and subsequently carried at amortised cost using the effective interest method. We measure onerous lease provisions at the lower of the cost to fulfil or to exit the contract.
Significant accounting policies that apply to share-based payments	Significant accounting policies that apply to share-based payments BT Group plc operates a number of equity settled share-based payment arrangements, under which the group receives services from employees in consideration for equity instruments (share options and shares) in BT Group plc. Equity-settled share-based payments are measured at fair value at the date of grant. Market-based performance criteria and non-vesting conditions (for example, the requirement for employees to make contributions to the share purchase programme) are reflected in this measurement of fair value. The fair value determined at the grant date is recognised as an expense on a straight line basis over the vesting period, based on the group’s estimate of the options or shares that will eventually vest and adjusted for the effect of non market-based vesting conditions. Fair value is measured using either the Binomial options pricing model or Monte Carlo simulations, whichever is more appropriate to the share-based payment arrangement. Service and performance conditions are vesting conditions. Any other conditions are non-vesting conditions which have to be taken into account to determine the fair value of equity instruments granted. In the case that an award or option does not vest as a result of a failure to meet a non-vesting condition that is within the control of either counterparty, this is accounted for as a cancellation. Cancellations are treated as accelerated vesting and all remaining future charges are immediately recognised in the income statement. As the requirement to save under an employee saveshare arrangement is a non-vesting condition, employee cancellations, other than through a termination of service, are treated as an accelerated vesting. No adjustment is made to total equity for awards that lapse or are forfeited after the vesting date.
Significant accounting policies that apply to cash and cash equivalents	Significant accounting policies that apply to cash and cash equivalents Cash and cash equivalents comprise cash in hand and current balances with banks and similar institutions, which are readily convertible to cash and are subject to insignificant risk of changes in value and have an original maturity of three months or less. All are held at amortised cost on the balance sheet, equating to fair value. For the purpose of the consolidated cash flow statement, cash and cash equivalents are as defined above net of outstanding bank overdrafts. Bank overdrafts are included within the current element of loans and other borrowings (note 23).
Significant accounting policies that apply to segment information	Significant accounting policies that apply to segment information Operating and reportable segments Our operating segments are reported based on financial information provided to the Executive Committee Our organisational structure reflects the different customer groups to which we provide communications products and services via our customer-facing units: Consumer, Enterprise, Global Services and Openreach. The customer-facing units are supported by an internal service unit, Technology, and corporate units including procurement and property management. The customer-facing units are our reportable segments and generate substantially all of our revenue. Technology and the group’s corporate units are not reportable segments as they did not meet the quantitative thresholds as set out in IFRS 8 ‘Operating Segments’ for any of the years presented. We aggregate the remaining operations and include within the ‘Other’ category to reconcile to the consolidated results of the group. The ‘Other’ category includes unallocated Technology costs and our corporate units. Allocation of certain items to segments Provisions for the settlement of significant legal, commercial and regulatory disputes, which are negotiated at a group level, are initially recorded in the ‘Other’ segment. On resolution of the dispute, the full impact is recognised in the results of the relevant customer-facing unit and offset in the group results through the utilisation of the provision previously charged to the ‘Other’ segment. Settlements which are particularly significant or cover more than one financial year may fall within the definition of specific items as detailed in note 10. The costs incurred by Technology and corporate units are recharged to the customer-facing units to reflect the services it provides to them. Depreciation and amortisation incurred by Technology in relation to the networks and systems it manages and operates on behalf of the customer-facing units is allocated to the customer-facing units based on their respective utilisation. Capital expenditure incurred by Technology for specific projects undertaken on behalf of the customer-facing units is allocated based on the value of the directly attributable expenditure incurred. Where projects are not directly attributable to a particular customer-facing unit, capital expenditure is allocated between them based on the proportion of estimated future economic benefits. Specific items are detailed in note 10 and are not allocated to the reportable segments as this reflects how they are reported to the Executive Committee Measuring segment performance Performance of each reportable segment is measured based on adjusted EBITDA. EBITDA is defined as the group profit or loss before interest, taxation, depreciation and amortisation. Adjusted EBITDA is defined as EBITDA before specific items, net non-interest related finance expense, and share of profits or losses of associates and joint ventures. Adjusted EBITDA is considered to be a useful measure of the operating performance of the customer-facing units because it approximates the underlying operating cash flow by eliminating depreciation and amortisation and also provides a meaningful analysis of trading performance by excluding specific items, which are disclosed separately by virtue of their size, nature or incidence. Revenue recognition Our revenue recognition policy is set out in the following note. Internal revenue and costs Most of our internal trading relates to Openreach and arises on rentals, and any associated connection or migration charges, of the UK access lines and other network products to the customer-facing units, including the use of BT Ireland’s network. This occurs both directly, and also indirectly, through Technology which is included within the ‘Other’ segment. Enterprise internal revenue arises from Consumer for mobile Ethernet access and Technology for transmission planning services. Internal revenue arising in Consumer relates primarily to employee broadband and wi-fi services. Intra-group revenue generated from the sale of regulated products and services is based on market price. Intra-group revenue from the sale of other products and services is agreed between the relevant customer-facing units and therefore the profitability of customer-facing units may be impacted by transfer pricing levels. Geographic segmentation The UK is our country of domicile and we generate the majority of our revenue from external customers in the UK. The geographic analysis of revenue is based on the country of origin in which the customer is invoiced. The geographic analysis of non-current assets, which exclude derivative financial instruments, investments and deferred tax assets, is based on the location of the assets.
Significant accounting policies that apply to contract assets and liabilities	Significant accounting policies that apply to contract assets and liabilities We recognise contract assets for goods and services for which control has transferred to the customer before consideration is due. These assets mainly relate to mobile handsets provided upfront but paid for over the course of a contract. Contract assets are reclassified as receivables when the right to payment becomes unconditional and we have billed the customer. Contract liabilities are recognised when we have received advance payment for goods and services that we have not transferred to the customer. These primarily relate to fees received for connection and installation services that are not distinct performance obligations. Where the initial set-up, transition or transformation phase of a long-term contract is considered to be a distinct performance obligation we recognise a contract asset for any work performed but not billed. Conversely a contract liability is recognised where these activities are not distinct performance obligations and we receive upfront consideration. In this case eligible costs associated with delivering these services are capitalised as fulfilment costs, see note 16. We provide for expected lifetime losses on contract assets following the policy set out in note 16.
Significant accounting policies that apply to specific items	Significant accounting policies that apply to specific items We separately identify and disclose those items that in management’s judgement need to be disclosed by virtue of their size, nature or incidence (termed ‘specific items’). Specific items are used to derive the adjusted results as presented in the consolidated income statement presented on page [XX]. Adjusted results are consistent with the way that financial performance is measured by management and assists in providing an additional analysis of the reporting trading results of the group. Specific items may not be comparable to similarly titled measures used by other companies. In determining whether an event or transaction is specific, management considers quantitative as well as qualitative factors. Examples of charges or credits meeting the above definition and which have been presented as specific items in the current and/or prior years include acquisitions/disposals of businesses and investments, retrospective regulatory matters, historical insurance or litigation claims, business restructuring programmes, asset impairment charges, property rationalisation programmes, net interest on pensions and the settlement of multiple tax years. In the event that items meet the criteria, which are applied consistently from year to year, they are treated as specific items.
Significant Accounting Policies Relating to Taxation	Significant accounting policies that apply to taxation Current income tax is calculated on the basis of the tax laws enacted or substantively enacted at the balance sheet date in the countries where the group’s subsidiaries, associates and joint ventures operate and generate taxable income. We periodically evaluate positions taken in tax returns with respect to situations in which applicable tax regulation is subject to interpretation, and establish provisions where appropriate on the basis of the amounts expected to be paid to tax authorities. Deferred tax is recognised, using the liability method, in respect of temporary differences between the carrying amount of our assets and liabilities and their tax base. Deferred tax is determined using tax rates that are expected to apply in the periods in which the asset is realised or liability settled, based on tax rates and laws that have been enacted or substantively enacted by the balance sheet date. Deferred income tax assets and liabilities are offset when there is a legally enforceable right to offset current tax assets against current tax liabilities and when the deferred income tax assets and liabilities relate to income taxes levied by the same taxation authority on either the taxable entity or different taxable entities where there is an intention to settle the balances on a net basis. Any remaining deferred tax asset is recognised only when, on the basis of all available evidence, it can be regarded as probable that there will be suitable taxable profits, within the same jurisdiction, in the foreseeable future against which the deductible temporary difference can be utilised. Deferred tax balances for which there is a right of offset within the same jurisdiction are presented net on the face of the group balance sheet as permitted by IAS 12, with the exception of deferred tax related to our pension schemes which is disclosed within deferred tax assets. Critical accounting judgements and key estimates made in accounting for taxation We seek to pay tax h w o o n i e e d u e a a e a e un a a a a a g u i a a u o o o g t g o W e i u o n b u a n i - u b a e n i a r e t h e e l a l l w h e t h e u i n o u d e l e t b a u a u i t n h e i a g u a n u e t h h o t a e W o d o t h o o w h e o u l o p a l b u h g a u a i a e l o o u a e p i l u o p i n a n e a i a o i o n h r e o t e t a e o h 1 o £ 252 0 18 £ 240 l e u n a i e i a e n n t i e U n e d u h b b Deciding whether to recognise deferred tax assets is judgemental. We only recognise them when we consider it is probable that they can be recovered. In making this judgement we consider evidence such as historical financial performance, future financial plans and trends, the duration of existing customer contracts and whether our intra-group pricing model has been agreed by the relevant tax authority. The value of the group’s income tax assets and liabilities is disclosed on the group balance sheet
Significant accounting policies that apply to intangible assets	Significant accounting policies that apply to intangible assets We recognise identifiable intangible assets where we control the asset, it is probable that future economic benefits attributable to the asset will flow to the group, and we can reliably measure the cost of the asset. We amortise all intangible assets, other than goodwill, over their useful economic life. The method of amortisation reflects the pattern in which the assets are expected to be consumed. If the pattern cannot be determined reliably, the straight line method is used. Goodwill Goodwill represents the excess of the cost of an acquisition over the fair value of the group’s share of the identifiable net assets (including intangible assets) of the acquired business. Our goodwill impairment policy is set out later in this note. Acquired intangible assets – customer relationships and brands Intangible assets such as customer relationships or brands acquired through business combinations are recorded at fair value at the date of acquisition and subsequently carried at amortised cost. Assumptions are used in estimating the fair values of these relationships or brands and include management’s estimates of revenue and profits to be generated by them. Telecommunications licences Licence fees paid to governments, which permit telecommunications activities to be operated for defined periods, are initially recorded at cost and amortised from the time the network is available for use to the end of the licence period or where our usage can extend beyond the initial licence period, over the period we expect to benefit from the use of the licences, which is typically 20 years. Licences acquired through business combinations are recorded at fair value at the date of acquisition and subsequently carried at amortised cost. The fair value is based on management’s assumption of future cash flows using market expectations at acquisition date. Computer software Computer software comprises computer software licences purchased from third parties, and also the cost of internally developed software. Computer software licences purchased from third parties are initially recorded at cost. We only capitalise costs directly associated with the production of internally developed software, including direct and indirect labour costs of development, where it is probable that the software will generate future economic benefits, the cost of the asset can be reliably measured and technical feasibility can be demonstrated, in which case it is capitalised as an intangible asset on the balance sheet. Costs which do not meet these criteria and research costs are expensed as incurred. Our development costs which give rise to internally developed software include upgrading the network architecture or functionality and developing service platforms aimed at offering new services to our customers. Other Other intangible assets include website development costs and other licences. Items are capitalised at cost and amortised on a straight line basis over their useful economic life or the term of the contract. Estimated useful economic lives The estimated useful economic lives assigned to the principal categories of intangible assets are as follows: – Computer r 2 r – Telecommunications 2 r – Customer r n r 1 r Impairment of intangible assets Intangible assets with finite useful lives are tested for impairment if events or changes in circumstances (assessed at each reporting date) indicate that the carrying amount may not be recoverable. When an impairment test is performed, the recoverable amount is assessed by reference to the higher of the net present value of the expected future cash flows (value in use) of the relevant cash generating unit and the fair value less costs to dispose. Goodwill is reviewed for impairment at least annually as described below. Impairment losses are recognised in the income statement, as a specific item. If a cash generating unit is impaired, impairment losses are allocated firstly against goodwill, and secondly on a pro-rata basis against intangible and other assets.
Significant accounting policies that apply to impairment of goodwill	Significant accounting policies that apply to impairment of goodwill We perform an annual goodwill impairment review . Goodwill recognised in a business combination does not generate cash flows independently of other assets or groups of assets. As a result, the recoverable amount, being the value in use, is determined at a cash generating unit (CGU) level. These CGUs represent the smallest identifiable groups of assets that generate cash inflows that are largely independent of the cash inflows from other groups of assets. Our CGUs are de e med to be legacy BT Consumer, legacy EE, Enterprise, and Global Services. We allocate goodwill to each of the Cash Generating Units (CGUs) that we expect to benefit from the business combination. Each CGU to which goodwill is allocated represents the lowest level within the group at which the goodwill is monitored for internal management purposes. The value in use of each CGU is determined using cash flow projections derived from financial plans approved by the Board covering a five-year period. They reflect management’s expectations of revenue, EBITDA growth, capital expenditure, working capital and operating cash flows, based on past experience and future expectations of business performance. Cash flows beyond the fifth year have been extrapolated using perpetuity growth rates.
Significant accounting policies that apply to programme rights	Significant accounting policies that apply to programme rights Programme rights are recognised on the balance sheet from the point at which the legally enforceable licence period begins. They are initially recognised at cost and are amortised from the point at which they are available for use, on a straight line basis over the programming period, or the remaining licence term, as appropriate, which is generally 12 months. Programme rights are tested for impairment in accordance with our impairment policy as set out in note 13. Additions g u . Programmes produced internally are charged to the income statement over the period of the related broadcast.
Significant accounting policies that apply to retirement benefits	Significant accounting policies that apply to retirement benefits Defined benefit plans Our net obligation in respect of defined benefit pension plans is the present value of the defined benefit obligation less the fair value of the plan assets. The income statement expense is allocated between an operating charge and net finance income or expense. - The operating charge reflects the increase in the defined benefit obligation resulting from the pension benefit earned by active employees in the current period, the costs of administering the plans and any past service costs/credits such as those arising from curtailments or settlements. - The net finance income or expense reflects the interest on the net retirement benefit obligations recognised in the group balance sheet, based on the discount rate at the start of the year. Remeasurements of the net pension obligation are recognised in full in the group statement of comprehensive income in the year in which they arise. These comprise the impact on the defined benefit obligation of changes in demographic and financial assumptions compared with the start of the year, actual experience being different to those assumptions and the return on plan assets being above or below the amount included in the net pension interest expense. Defined contribution plans
Significant accounting policies that apply to investments	Significant accounting policies that apply to investments Investments classified as amortised cost These investments are Investments classified as fair value through profit and loss These investments are initially recognised at fair value plus direct transaction costs. They are re-measured at subsequent reporting dates to fair value and changes are recognised directly in the income statement. Debt instruments classified as fair value through other comprehensive income These investments are initially recognised at fair value plus direct transaction costs. Investments are re-measured at subsequent reporting dates to fair value, and unrealised gains and losses are recognised in other comprehensive income (except for changes in exchange rates for monetary items, interest, and impairment losses, which are recognised in the income statement). On derecognition of the investment, the cumulative gain or loss previously recognised in other comprehensive income is taken to the income statement, in the line that most appropriately reflects the nature of the item or transaction. Equity instruments classified as fair value through other comprehensive income We have made an irrevocable election to present changes in the fair value of equity investments that are not held for trading in other comprehensive income. All gains or losses are recognised in other comprehensive income and are not reclassified to the income statement when the investments are disposed of, aside from dividends which are recognised in the income statement when our right to receive payment is established. Equity investments are recorded in non-current assets unless they are expected to be sold within one year.
Significant accounting policies that apply to loans and other borrowings	Significant accounting policies that apply to loans and other borrowings We initially recognise loans and other borrowings at the fair value of amounts received net of transaction costs. They are subsequently measured at amortised cost using the effective interest method and, if included in a fair value hedge relationship, are re-valued to reflect the fair value movements on the associated hedged risk. The resulting amortisation of fair value movements, on de-designation of the hedge, is recognised in the income statement.
Significant accounting policies that apply to derivatives and hedge accounting	Significant accounting policies that apply to derivatives and hedge accounting All of our derivative financial instruments are held at fair value on the balance sheet. Derivatives designated in a cash flow hedge The group designates certain derivatives as cash flow hedges. Where derivatives qualify for hedge accounting, recognition of any resultant gain or loss depends on the nature of the hedge. The group designates certain derivatives as cash flow hedges. To qualify for hedge accounting, hedge documentation must be prepared at inception, the hedge must be in line with BT’s risk management strategy and there must be an economic relationship based on currency, amount and timing of the respective cashflows of the hedged item and the hedging instrument. This is assessed at inception and in subsequent periods in which the hedge remains in operation. Hedge accounting is discontinued when it is no longer in line with BT Group’s risk management strategy or if it no longer qualifies for hedge accounting. When a derivative financial instrument is designated as a hedge of the variability in cash flows of a recognised asset or liability, or a highly probable transaction, the effective part of any gain or loss on the derivative financial instrument is recognised directly in equity, in the cash flow reserve. For cash flow hedges of recognised assets or liabilities, the associated cumulative gain or loss is removed from equity and recognised in the same line of the income statement and in the same period or periods that the hedged transaction affects the income statement. Any ineffectiveness arising on a cash flow hedge is recognised immediately in the income statement. Other derivatives Our policy is not to use derivatives for trading purposes. However, due to the complex nature of hedge accounting, some derivatives may not qualify for hedge accounting, or may be specifically not designated as a hedge because natural offset is more appropriate. These derivatives are classified as fair value through profit and loss and are recognised at fair value. Any direct transaction costs are recognised immediately in the income statement. Gains and losses on re-measurement are recognised in the income statement in the line that most appropriately reflects the nature of the item or transaction to which they relate. Derivative financial instruments are classified as current assets or current liabilities where they have a maturity period within 12 months. Where derivative financial instruments have a maturity period greater than 12 months, they are classified within either non-current assets or non-current liabilities. Where the fair value of a derivative contract at initial recognition is not supported by observable market data and differs from the transaction price, a day one gain or loss will arise which is not recognised in the income statement. Such gains and losses are deferred and amortised to the income statement based on the remaining contractual term and as observable market data becomes available. The fair values of outstanding swaps and foreign exchange contracts are estimated using discounted cash flow models and market rates of interest and foreign exchange at the balance sheet date.

Basis of preparation (Tables)

Basis of preparation (Tables)	12 Months Ended
	Mar. 31, 2019
Basis Of Preparation [Abstract]
Summary of Impact of the Adoption of IFRS 15 on the Financial Statement	The impact of the adoption of IFRS 15 on opening retained earnings at 1 April 2018 is shown in note 2. The following tables show, for the year ended 31 March 2019, the impact had the IFRS 15 standard not been adopted on the financial statement line items affected for the income statement and balance sheet. There was no net impact on the key cash flow captions (net cash flow from operating activities, net cash flow from investing activities or net cash flow from financing activities). Group income statement Year ended 31 March 2019 As reported (IFRS 15) £m Adjustments £m Amounts without adoption of IFRS 15 (IAS 18) £m Revenue 23,428 (252 ) 23,176 Operating costs (20,004 ) 1 (20,003 ) Operating profit 3,424 (251 ) 3,173 Profit before tax 2,898 (251 ) 2,647 Tax (551 ) 48 (503 ) Profit for the year 2,347 (203 ) 2,144 Group balance sheet As at 31 March 2019 As reported (IFRS 15) £m Adjustments £m Amounts without adoption of IFRS 15 (IAS 18) £m Non-current assets Contract assets 249 (249 ) — Trade and other receivables 445 (149 ) 296 Current assets Contract assets 1,353 (1,353 ) — Trade and other receivables 3,238 180 3,418 Current tax receivable 110 296 406 Current liabilities Trade and other payables 5,827 1,313 7,140 Contract liabilities 1,225 (1,225 ) — Total assets less current liabilities 49,367 (1,363 ) 48,004 Non-current liabilities Trade and other payables 1,479 102 1,581 Contract liabilities 200 (200 ) — Equity Retained earnings 10,191 (1,265 ) 8,926 Total equity and non-current liabilities 49,367 (1,363 ) 48,004

Prior Year Restatement and Op_2

Prior Year Restatement and Opening Balance Adjustments (Tables)	12 Months Ended
	Mar. 31, 2019
Prior Year Restatement And Opening Balance Adjustments [Abstract]
Summary of Impact of Restatement and Opening Balance Adjustments	Year ended 31 March 2018 (as published) Pension restatement Year ended 31 March 2018 (restated) £m £m £m Profit for the period 2,184 - 2,184 Other comprehensive income (loss) Items that will not be reclassified to the income statement: Remeasurements of the net pension obligation 2,160 (476 ) 1,684 Tax on pension remeasurements (346 ) 83 (263 ) Items that have been or may be reclassified subsequently to the income statement: Exchange differences on translation of foreign operations (188 ) - (188 ) Fair value movements on available-for-sale assets 11 - 11 Movements in relation to cash flow hedges: - net fair value (losses) gains (368 ) - (368 ) - recognised in income and expense 277 - 277 Tax on components of other comprehensive income that have been or may be reclassified 1 - 1 Other comprehensive profit (loss) for the period, net of tax 1,547 (393 ) 1,154 Total comprehensive income (loss) for the period 3,731 (393 ) 3,338 At 31 March 2018 (as published) Pension restatement At 31 March 2018 (restated) IFRS 9 & 15 opening balance adjustment At 1 April 2018 £m £m £m £m £m Non-current assets Intangible assets 14,455 - 14,455 - 14,455 Property, plant and equipment 17,000 - 17,000 - 17,000 Trade and other receivables 317 - 317 114 431 Contract assets - - - 198 198 Deferred tax assets 1,243 83 1,326 - 1,326 Other non-current assets 14,704 - 14,704 - 14,704 47,719 83 47,802 312 48,114 Current assets - Trade and other receivables 4,029 - 4,029 (337 ) 3,692 Contract assets - - - 1,417 1,417 Cash and cash equivalents 521 - 521 - 521 Other current assets 4,009 - 4,009 - 4,009 8,559 - 8,559 1,080 9,639 Current liabilities Loans and other borrowings 2,298 - 2,298 - 2,298 Trade and other payables 7,190 - 7,190 (1,409 ) 5,781 Contract liabilities - - - 1,406 1,406 Current tax liabilities 83 - 83 248 331 Other current liabilities 653 - 653 - 653 10,224 - 10,224 245 10,469 Total assets less current liabilities 46,054 83 46,137 1,147 47,284 Non-current liabilities Loans and other borrowings 13,038 - 13,038 - 13,038 Contract liabilities - - - 87 87 Retirement benefit obligations 6,371 476 6,847 - 6,847 Other non-current liabilities 3,905 - 3,905 - 3,905 23,314 476 23,790 87 23,877 Equity - Share capital 2,172 - 2,172 - 2,172 All other reserves 9,241 - 9,241 - 9,241 Retained earnings 11,327 (393 ) 10,934 1,060 11,994 Total equity 22,740 (393 ) 22,347 1,060 23,407 46,054 83 46,137 1,147 47,284

Segment information (Tables)

Segment information (Tables)	12 Months Ended
	Mar. 31, 2019
Disclosure Of Operating Segments [Abstract]
Summary of Results of Reportable Segments	S e e e e a i As explained in note 2, our reportable segments changed during the year as a result of a reduction in the number of our customer-facing units. The BT Consumer and EE segments disclosed in last year’s accounts have been combined into a single reportable segment named ‘Consumer’, and the Business and Public Sector and Wholesale and Ventures segments now form a single reportable segment, ‘Enterprise’. We also transferred our Northern Ireland Networks business from Enterprise to Openreach and reclassified certain internal revenues generated by our Ventures businesses as segmental revenue rather than as an internal recovery of cost. The prior year comparatives presented in this note have been restated to reflect these changes. Year ended 31 March 2019 (IFRS 15) Consumer £m Enterprise £m Global Services £m Openreach £m Other £m Total £m Segment revenue 10,695 6,292 4,735 5,075 3 26,800 Internal revenue (107 ) (359 ) – (2,875 ) – (3,341 ) Revenue from external customers a 10,588 5,933 4,735 2,200 3 23,459 Adjusted EBITDA b 2,534 1,990 505 2,423 (57 ) 7,395 Depreciation and amortisation a (1,024 ) (634 ) (370 ) (1,468 ) (50 ) (3,546 ) Operating profit (loss) a 1,510 1,356 135 955 (107 ) 3,849 Specific items (note 10) (425 ) Operating profit 3,424 Net finance expense c (527 ) Share of post tax profit (loss) of associates and joint ventures 1 Profit before tax 2,898 Year ended 31 March 2018 (restated) (IAS 18) Consumer £m Enterprise d £m Global Services £m Openreach d £m Other £m Total £m Segment revenue 10,360 6,647 5,013 5,278 8 27,306 Internal revenue (103 ) (441 ) – (3,016 ) – (3,560 ) Revenue from external customers a 10,257 6,206 5,013 2,262 8 23,746 Adjusted EBITDA b 2,376 2,077 434 2,615 6 7,508 Depreciation and amortisation a (992 ) (635 ) (424 ) (1,401 ) (62 ) (3,514 ) Operating profit (loss) a 1,384 1,442 10 1,214 (56 ) 3,994 Specific items (note 10) (610 ) Operating profit 3,384 Net finance expense c (579 ) Share of post tax profit (loss) of associates and joint ventures (1 ) Profit before tax 2,804 Year ended 31 March 2017 (restated) (IAS 18) Consumer £m Enterprise d £m Global Services £m Openreach d £m Other £m Total £m Segment revenue 10,024 6,975 5,479 5,250 10 27,738 Internal revenue (100 ) (480 ) – (3,076 ) – (3,656 ) Revenue from external customers a 9,924 6,495 5,479 2,174 10 24,082 Adjusted EBITDA b 2,168 2,261 495 2,734 (10 ) 7,648 Depreciation and amortisation a (989 ) (613 ) (439 ) (1,414 ) (55 ) (3,510 ) Operating profit (loss) a 1,179 1,648 56 1,320 (65 ) 4,138 Specific items (note 10) (968 ) Operating profit 3,170 Net finance expense c (610 ) Share of post tax profit (loss) of associates and joint ventures (9 ) Profit before tax 2,551 a Before specific items. b c Net finance expense includes specific item expense of £ 139 m (2017/18: £218m, 2016/17: £210m). See note 10. d On 1 October 2018 we transferred our Northern Ireland Networks business from Enterprise to Openreach which resulted in an increase in segment revenue, Adjusted EBITDA and Operating profit in Openreach of £155m, £95m, and £54m and a decrease in segment revenue, Adjusted EBITDA and Operating profit in Enterprise of £117m, £95m, and £54m for the year ended 31 March 2018 and an increase in segment revenue, Adjusted EBITDA and Operating profit in Openreach of £152m, £101m, and £56m and a decrease in segment revenue, Adjusted EBITDA and Operating profit in Enterprise of £112m, £101m, and £56m for the year ended 31 March 2017. Additionally, within the Enterprise segment, we reclassified £224m and £242m of internal revenue generated by our Ventures businesses as segmental revenue rather than as an internal recovery of cost for the years ended 31 March 2018 and 2017, respectively.
Summary of Results of Internal Revenue and Costs	Internal revenue and costs Internal cost recorded by Year ended 31 March 2019 Consumer £m Enterprise £m Global Services £m Openreach £m Other £m Total £m Internal revenue recorded by Consumer – 69 20 – 18 107 Enterprise 63 – 51 177 68 359 Global Services – – – – – – Openreach 920 401 112 – 1,442 2,875 Total 983 470 183 177 1,528 3,341 Internal cost recorded by Year ended 31 March 2018 Consumer £m Enterprise £m Global Services £m Openreach £m Other £m Total £m Internal revenue recorded by Consumer – 65 20 – 18 103 Enterprise a 130 – 51 173 87 441 Global Services – – – – – – Openreach a 896 480 125 – 1,515 3,016 Total 1,026 545 196 173 1,620 3,560 Internal cost recorded by Year ended 31 March 2017 Consumer £m Enterprise £m Global Services £m Openreach £m Other £m Total £m Internal revenue recorded by Consumer – 62 20 – 18 100 Enterprise a 148 – 71 165 96 480 Global Services – – – – – – Openreach a 910 536 158 – 1,472 3,076 Total 1,058 598 249 165 1,586 3,656 a On 1 October 2018 we transferred our Northern Ireland Networks business from Enterprise to Openreach and we reclassified certain internal revenues generated by our Ventures businesses as segmental revenue rather than an internal recovery of cost. This increases internal revenue recorded by Enterprise by £224m in the year ended 31 March 2018 and £242m in the year ended 31 March 2017. Internal revenue for Openreach has increased by £38m in the year ended 31 March 2018 and £40m in the year ended 31 March 2017.
Summary of Capital Expenditure	Capital expenditure Year ended 31 March 2019 Consumer £m Enterprise £m Global Services £m Openreach £m Other £m Total £m Intangible assets a 276 180 93 82 49 680 Property, plant and equipment b 718 321 152 1,999 93 3,283 Capital expenditure 994 501 245 2,081 142 3,963 Acquisition of spectrum a – – – – 304 304 Capital expenditure including spectrum 994 501 245 2,081 446 4,267 Year ended 31 March 2018 (restated) Consumer £m Enterprise £m Global Services £m Openreach £m Other £m Total £m Intangible assets a 236 180 92 70 64 642 Property, plant and equipment b,c 683 312 186 1,629 70 2,880 Capital expenditure 919 492 278 1,699 134 3,522 Year ended 31 March 2017 (restated) Consumer £m Enterprise £m Global Services £m Openreach £m Other £m Total £m Intangible assets a 225 141 126 74 55 621 Property, plant and equipment b,c 628 313 235 1,546 111 2,833 Capital expenditure 853 454 361 1,620 166 3,454 a Additions to intangible assets as presented in note 13. b Additions to property, plant and equipment as presented in note 14, inclusive of movement on engineering stores. c On 1 October 2018 we transferred our Northern Ireland Networks business from Enterprise to Openreach. This decreased property, plant and equipment in Enterprise and increased property, plant and equipment in Openreach by £41m and £47m in the years ended 31 March 2018 and 31 March 2017 respectively.
Summary of Geographic Information by Revenue from External Customers and Non-Current Assets	Revenue from external customers Year ended 31 March 2019 £m 2018 £m 2017 £m UK 19,683 19,687 19,421 Europe, Middle East and Africa, excluding the UK 2,280 2,489 2,841 Americas 936 996 1,148 Asia Pacific 560 574 672 Revenue a 23,459 23,746 24,082 a Before specific items. Non-current assets At 31 March 2019 £m 2018 £m 2017 £m UK 30,057 28,843 28,818 Europe, Middle East and Africa, excluding the UK 2,217 2,527 2,535 Americas 336 331 424 Asia Pacific 110 109 149 Non-current assets a 32,720 31,810 31,926 a

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Mar. 31, 2019
Revenue From Contracts With Customers [Abstract]
Summary of Disaggregation of Revenue From Contracts With Customers	The following table disaggregates revenue from contracts with customers by our major service lines and by reportable segment. The prior year comparatives have been presented consistent with the presentation in last year’s Annual Report under IAS 18. Consumer Enterprise Global Services Openreach Other Total Year ended 31 March 2019 (IFRS 15) £m £m £m £m £m £m ICT and managed networks – 2,236 2,613 – – 4,849 Fixed access subscriptions 4,564 2,181 362 2,135 – 9,242 Mobile subscriptions 3,866 1,277 130 – – 5,273 Equipment and other services 2,158 239 1,630 65 3 4,095 Revenue 10,588 5,933 4,735 2,200 3 23,459 Specific items (note 10) (31 ) Revenue 23,428 2018 2017 Year ended 31 March (IAS 18) £m £m ICT and managed networks 5,530 5,927 Broadband and TV 4,655 4,477 Mobile 6,451 6,358 Calls, lines and connections 5,126 5,069 Transit 265 404 Other products and services 1,719 1,847 Revenue before specific items 23,746 24,082 Specific items (note 10) (23 ) (20 ) Revenue 23,723 24,062
Summary of Contract Assets and Liabilities Recognised	Contract assets and liabilities recognised at 31 March 2019 are as follows: 31 March 2019 £m 1 April 2018 £m Contract assets Current 1,353 1,417 Non-current 249 198 1,602 1,615 Contract liabilities Current 1,225 1,406 Non-current 200 87 1,425 1,493

Operating Costs (Tables)

Operating Costs (Tables)	12 Months Ended
	Mar. 31, 2019
Operating Costs [Abstract]
Summary of Operating Costs	Year ended 31 March Notes 2019 £m 2018 £m 2017 £m Operating costs by nature Staff costs: Wages and salaries 4,258 4,223 4,128 Social security costs 440 461 477 Other pension costs 19 611 624 521 Share-based payment expense 20 67 84 57 Total staff costs 5,376 5,392 5,183 Own work capitalised (834 ) (798 ) (813 ) Net staff costs 4,542 4,594 4,370 Net indirect labour costs a 267 315 399 Net labour costs 4,809 4,909 4,769 Product costs and sales commission b 4,464 4,429 4,588 Payments to telecommunications operators 2,059 2,306 2,653 Property and energy costs 1,325 1,285 1,202 Network operating and IT costs 1,026 963 983 TV programme rights charges 841 763 714 Provision and installation b 624 657 669 Marketing and sales b 322 317 365 Other operating costs b 832 831 676 Other operating income (238 ) (222 ) (185 ) Depreciation of property, plant and equipment Owned assets 14 2,390 2,381 2,382 Held under finance leases 14 2 10 10 Amortisation of intangible assets c 13 1,154 1,123 1,118 Total operating costs before specific items 19,610 19,752 19,944 Specific items 10 394 587 948 Total operating costs 20,004 20,339 20,892 Operating costs before specific items include the following: Leaver costs d 17 50 86 Research and development expenditure e 643 632 638 Operating lease charges 801 732 692 Foreign currency gains (11 ) – (12 ) Inventories recognised as an expense 2,388 2,588 2,680 Government grants (3 ) (3 ) (5 ) a b Included within ‘other operating costs’ in prior years were costs relating to product costs and commissions; provision and installation; and marketing and sales. These are now presented separately. The ‘other operating costs’ in comparative for 2017/18 and 2016/17 has been re-presented for consistency. c Excludes £nil (2017/18: £nil, 2016/17: £62m) of amortisation presented as specific items which relate to a write off of software costs as a result of the integration of EE. d Leaver costs are included within wages and salaries, except for leaver costs of £257m (2017/18: £168m, 2016/17: £37m) associated with restructuring and EE integration costs, which have been recorded as specific items. e Research and development expenditure reported in the income statement, includes amortisation of £581m (2017/18: £573m, 2016/17: £577m) in respect of internally developed computer software and operating expenses of £62m (2017/18: £59m, 2016/17: £61m). In addition, the group capitalised software development costs of £472m (2017/18: £450m, 2016/17: £457
Summary of Compensation of Key Management Personnel	Compensation of key management personnel is shown in the table below: Year ended 31 March 2019 £m 2018 £m 2017 £m Short-term employee benefits 14.9 12.4 10.9 Post employment benefits 1.4 1.4 1.4 Share-based payments 5.2 6.6 5.8 Termination benefits 0.6 2.2 – 22.1 22.6 18.1

Employees (Tables)

Employees (Tables)	12 Months Ended
	Mar. 31, 2019
Employees [Abstract]
Summary of Number of Employees in the Group	2019 2018 2017 Number of employees in the group a Year end 000 Average 000 Year end 000 Average 000 Year end 000 Average 000 UK 84.3 83.4 82.2 82.5 82.8 82.2 Non-UK 22.4 23.1 23.6 23.7 23.6 22.8 Total employees 106.7 106.5 105.8 106.2 106.4 105.0 As explained in note 2, we reduced the number of our customer-facing units during the year. BT Consumer and EE have been combined into ‘Consumer’, and Business and Public Sector and Wholesale and Ventures have been combined into ‘Enterprise’. We also transferred c. 700 employees in our Northern Ireland Networks business from Enterprise to Openreach. The prior year comparatives presented in the table below have been restated to reflect these changes. 2019 2018 2017 Number of employees in the group a Year end 000 Average 000 Year end 000 Average 000 Year end 000 Average 000 Consumer 19.7 19.0 18.2 18.0 17.9 16.8 Enterprise b 13.4 13.8 13.2 13.5 13.4 13.2 Global Services 16.6 16.8 16.9 17.3 17.5 17.4 Openreach b 33.2 31.9 31.2 31.1 30.9 31.6 Other 23.8 25.0 26.3 26.3 26.7 26.0 Total employees 106.7 106.5 105.8 106.2 106.4 105.0 a These reflect the full-time equivalent of full and part-time employees. b The 2018 and 2017 comparatives have been restated to reflect the change in segments and the transfer of Nothern Ireland Networks as described above.

Audit, audit related and othe_2

Audit, audit related and other non-audit services (Tables)	12 Months Ended
	Mar. 31, 2019
Non Audit Fees [Abstract]
Summary of Fees Paid or Payable to Company's Auditors	The following fees were paid or are payable to the company’s auditors, KPMG LLP and other firms in the KPMG network, for the year ended 31 March 2019. Figures in the table below for the years ended 31 March 2017 and 2018 are in respect of fees paid to the company’s previous auditors, PricewaterhouseCoopers LLP. Year ended 31 March 2019 £000 2018 £000 2017 £000 Fees payable to the company’s auditors and its associates for: Audit services a,b The audit of the parent company and the consolidated financial statements 8,118 5,372 4,271 The audit of the company’s subsidiaries 6,049 5,866 5,664 14,167 11,238 9,935 Audit related assurance services c 2,236 1,631 1,865 Other non-audit services Taxation compliance services d – - 366 Taxation advisory services e – - 111 All other assurance services f 748 211 200 All other services g 210 592 2,332 958 803 3,009 Total services 17,361 13,672 14,809 a Services in relation to the audit of the parent company and the consolidated financial statements, including fees for reports under section 404 of the Sarbanes-Oxley Act. This also includes fees payable for the statutory audits of the financial statements of subsidiary companies. This excludes amounts for the audit of BT Group Employee Share Ownership Trust and Ilford Trustees (Jersey) Limited amounting to £32,000. b During the year a further £446,000 of fees were payable to PricewaterhouseCoopers LLP in relation to the audit of 2017/18 subsidiary accounts and the audit of our restated IAS19 accounting valuation of retirement benefit obligations, which have not been included in the 2019 balances in the above table. c Services in relation to other statutory filings or engagements that are required by law or regulation to be carried out by an appointed auditor. This includes fees for the review of interim results, the accrued fee for the audit of the group’s regulatory financial statements and reporting associated with the group’s US debt shelf registration. d Services relating to tax returns, tax audits, monitoring and enquiries. e Fees payable for all taxation advisory services not falling within taxation compliance. f All other assurance services include fees payable to KPMG LLP for agreed upon procedures performed on the estimated impact of the new IFRS 15 revenue accounting standard, which took effect from 1 April 2018 for the 2017/18 audit. g Fees payable for all non-audit services not covered above, principally comprising other advisory services.
Summary of Total Fees Received by Company's Auditors from the BT Pension Scheme	In h a e e a L L i a e f h e o h e m o 1.1 2 1 / 7 2.1 e h o o i i Year ended 31 March 2019 £000 2018 £000 2017 £000 Audit of financial statements of associates 1,005 345 251 Audit-related assurance services 53 – – Taxation compliance services – 153 210 Taxation advisory services – 1,074 493 Other non-audit services 62 565 1,168 Total services 1,120 2,137 2,122

Specific items (Tables)

Specific items (Tables)	12 Months Ended
	Mar. 31, 2019
Specific Items [Abstract]
Summary of Specific Items	Year ended 31 March 2019 £m 2018 £m 2017 £m Revenue Italian business investigation – – 22 Retrospective regulatory matters 31 23 (2 ) 31 23 20 Operating costs EE acquisition warranty claims – 225 – Restructuring charges 386 241 – EE integration costs – 46 215 Property rationalisation costs 36 28 – Pension equalisation costs 26 – – Retrospective regulatory matters (4 ) 26 481 Italian business investigation (55 ) 22 238 Out of period irrecoverable VAT – – 30 Profit (loss) on disposal of businesses 5 (1 ) (16 ) 394 587 948 Operating loss 425 610 968 Net finance expense Interest expense on retirement benefit obligation 139 218 209 Interest on out of period irrecoverable VAT – – 1 139 218 210 Net specific items charge before tax 564 828 1,178 Taxation Tax credit on specific items above (112 ) (87 ) (154 ) Tax credit on re-measurement of deferred tax – – (63 ) (112 ) (87 ) (217 ) Net specific items charge after tax 452 741 961

Taxation (Tables)

Taxation (Tables)	12 Months Ended
	Mar. 31, 2019
Taxation [Abstract]
Analysis of Our Taxation Expenses	A n x e s Year ended 31 March 2019 £m 2018 £m 2017 £m United Kingdom Corporation tax at 19% (2017/18: 19%, 2016/17: 20%) (478 ) (614 ) (594 ) Adjustments in respect of earlier years (9 ) 37 33 Non-UK taxation Current (74 ) (66 ) (109 ) Adjustments in respect of earlier years 15 23 - Total current tax expense (546 ) (620 ) (670 ) Deferred taxation Origination and reversal of temporary differences (20 ) 46 96 Adjustments in respect of earlier years 2 (57 ) 26 Impact of change in UK corporation tax rate to 17% (2017/18: 17%, 2016/17: 17%) - - 63 Remeasurement of temporary differences 13 11 - Total deferred taxation expense (credit) (5 ) - 185 Total taxation expense (551 ) (620 ) (485 )
Summary of Factors Affecting Our Taxation Expense for the Year	T h a o p o p e o h o p b a l n h p a t i h o f i t Year ended 31 March 2019 £m 2018 £m 2017 £m Profit before taxation 2,898 2,804 2,551 Expected taxation expense at UK rate of 19% (2017/18: 19%, 2016/17: 20%) (551 ) (533 ) (510 ) Effects of: (Higher) lower taxes on non-UK profits (7 ) (8 ) (29 ) Net permanent differences between tax and accounting a (35 ) (100 ) (183 ) Adjustments in respect of earlier years b 8 3 59 Prior year non-UK losses used against current year profits 21 16 120 Non-UK losses not recognised c - (9 ) (8 ) Other deferred tax assets not recognised - - - Lower taxes on profit on disposal of business - - 3 Re-measurement of deferred tax balances 13 11 63 Other non-recurring items - - - Total taxation expense (551 ) (620 ) (485 ) Exclude specific items (note 10) (112 ) (87 ) (217 ) Total taxation expense before specific items (663 ) (707 ) (702 ) a Includes income that is not taxable or UK income taxable at a different rate, and expenses for which no tax relief is received. Examples include some types of depreciation and amortisation and the benefit of R&D tax incentives. b Reflects the differences between initial accounting estimates and tax returns submitted to tax authorities, including the release and establishment of provisions for uncertain tax positions. c s m o e e n e c d p a o e e e f xa p n r b
Summary of Tax Components of Other Comprehensive Income	T a n e e e s c o m Year ended 31 March 2019 Tax credit (expense) £m 2018 Tax credit (expense) (Restated) £m 2017 Tax credit (expense) £m Tax on items that will not be reclassified to the income statement Pension remeasurements a 384 (263 ) 416 Tax on items that have been or may be reclassified subsequently to the income statement Exchange differences on translation of foreign operations (4 ) (9 ) 21 Fair value movements on cash flow hedges – net fair value gains or losses (37 ) 57 (131 ) – recognised in income and expense - (47 ) 139 343 (262 ) 445 Current tax credit b 395 203 122 Deferred tax (expense) credit (52 ) (465 ) 323 343 (262 ) 445 a Certain results have been restated to reflect the update to the calculation of our IAS 19 accounting valuation of retirement benefit obligations. See note 2. b I nclu d es £391 m (20 1 7/1 8 : £212m, 2 016 / 17: £ 110 m ) rel a ting to ca s h c o ntrib u tions ma d e to r e du c e reti r eme n t be n efit o blig a tion s.
Summary of Tax (Expense) Credit Recognised Directly in Equity	T a s e e d e n s e i Year ended 31 March 2019 £m 2018 £m 2017 £m Tax (expense) credit relating to share-based payments - (2 ) (6 )
Summary of Deferred Taxation	Deferred taxation Fixed asset temporary differences £m Retirement benefit obligations b £m Share- based payments £m Tax losses £m Other £m Jurisdictional offset £m Total (Restated) £m At 1 April 2017 1,432 (1,537 ) (17 ) (270 ) (85 ) – (477 ) Expense (credit) recognised in the income statement 11 (104 ) 4 89 0 – – Expense (credit) recognised in other comprehensive income (restated) a 0 475 – 0 (10 ) – 465 Expense (credit) recognised in equity – – 6 – – – 6 Exchange differences – – – (2 ) 5 – 3 Transfer to current tax 17 – – – – – 17 At 31 March 2018 1,460 (1,166 ) (7 ) (183 ) (90 ) – 14 Non-current Deferred tax asset (41 ) (1,166 ) (7 ) (183 ) (90 ) 161 (1,326 ) Deferred tax liability 1,501 – – – – (161 ) 1,340 At 1 April 2018 1,460 (1,166 ) (7 ) (183 ) (90 ) – 14 Expense (credit) recognised in the income statement (60 ) (59 ) 1 114 (1 ) – (5 ) Expense (credit) recognised in other comprehensive income - 15 - - 37 – 52 Expense (credit) recognised in equity - - (1 ) - – – (1 ) Exchange differences - - 1 (1 ) – – – At 31 March 2019 1,400 (1,210 ) (6 ) (70 ) (54 ) – 60 Non-current Deferred tax asset (27 ) (1,210 ) (6 ) (70 ) (54 ) 20 (1,347 ) Deferred tax liability 1,427 – – – – (20 ) 1,407 At 31 March 2019 1,400 (1,210 ) (6 ) (70 ) (54 ) – 60 a b I d e t s o 1 m i n t a i i o e n
Summary of Restricted Loss	A summary of ex p a e o o e e h t t o p e u e o At 31 March 2019 £m Expiry Restricted losses Europe 16 2019-2038 Americas 205 2019-2038 Other 3 2019-2038 Total restricted losses 224 Unrestricted operating losses 3,905 No expiry Other temporary differences 108 No expiry Total 4,237

Intangible assets (Tables)

Intangible assets (Tables)	12 Months Ended
	Mar. 31, 2019
Intangible Assets [Abstract]
Summary of Estimated Useful Economic Lives Assigned to Principal Categories of Intangible Assets	The estimated useful economic lives assigned to the principal categories of intangible assets are as follows: – Computer r 2 r – Telecommunications 2 r – Customer r n r 1 r
Summary of Intangible Assets	Goodwill £m Customer relationships and brands £m Telecoms licences and other £m Internally developed software £m Purchased software £m Total £m Cost At 1 April 2017 8,042 3,422 2,945 4,363 1,853 20,625 Additions – – – 517 125 642 Acquisitions 14 – 3 – – 17 Disposals and adjustments a (3 ) – (3 ) (55 ) (413 ) (474 ) Exchange differences (100 ) (12 ) 6 (3 ) 9 (100 ) At 31 March 2018 7,953 3,410 2,951 4,822 1,574 20,710 Additions – – 304 520 160 984 Disposals and adjustments a (2 ) – (3 ) (945 ) (141 ) (1,091 ) Transfers – – 4 120 (80 ) 44 Exchange differences 63 7 (4 ) 1 (8 ) 59 At 31 March 2019 8,014 3,417 3,252 4,518 1,505 20,706 Accumulated amortisation At 1 April 2017 – 813 280 3,193 1,302 5,588 Charge for the year – 379 141 525 78 1,123 Disposals and adjustments a – – (3 ) (36 ) (426 ) (465 ) Exchange differences – (1 ) 3 (2 ) 9 9 At 31 March 2018 – 1,191 421 3,680 963 6,255 Charge for the year – 377 142 525 110 1,154 Disposals and adjustments a – – (3 ) (941 ) (147 ) (1,091 ) Transfers – – 3 (43 ) 43 3 Exchange differences – 3 (3 ) – (8 ) (8 ) At 31 March 2019 – 1,571 560 3,221 961 6,313 Carrying amount At 31 March 2019 8,014 1,846 2,692 1,297 544 14,393 At 31 March 2018 7,953 2,219 2,530 1,142 611 14,455 a Fully depreciated assets in the group’s fixed asset registers were reviewed during the year, as part of the group’s annual asset verification exercise, and certain assets that were no longer in use have been written off, reducing cost and accumulated depreciation by £1.0bn (2017/18: £0.4bn).
Summary of Goodwill Allocated to Cash Generating Units	Cost Legacy BT Consumer £m Legacy EE £m Enterprise £m Business and Public Sector Wholesale and Ventures Global Services £m Total £m At 1 April 2017 1,183 2,768 – 2,570 942 579 8,042 Exchange differences – – – (8 ) – (92 ) (100 ) Acquisitions and disposals – – – – – 11 11 At 31 March 2018 1,183 2,768 — 2,562 942 498 7,953 Transfer – – 3,504 (2,562 ) (942 ) – – Exchange differences – – 5 – – 58 63 Acquisitions and disposals – – – – – (2 ) (2 ) At 31 March 2019 1,183 2,768 3,509 – – 554 8,014

Property, plant and equipment (

Property, plant and equipment (Tables)	12 Months Ended
	Mar. 31, 2019
Disclosure Of Property Plant And Equipment [Abstract]
Summary of Estimated Useful Lives Assigned to Principal Categories of Assets	The estimated useful lives assigned to principal categories of assets are as follows: Land and buildings – Freehold buildings 14 to 50 years – Short-term leasehold improvements Shorter of 10 years or lease term – Leasehold land and buildings Unexpired portion of lease or 4 0 years, whichever is the shorter Network infrastructure Transmission equipment – Duct 40 years – Cable 3 to 25 years – Fibre 5 to 20 years Exchange equipment 2 to 13 years Other network equipment 2 to 20 years Other assets – Motor vehicles 2 to 9 years – Computers and office equipment 3 to 7 years
Summary of the Carrying Values of Software, Property, Plant and Equipment	Land and buildings a £m Network infrastructure a £m Other b £m Assets in course of construction £m Total £m Cost At 31 March 2017 1,302 49,372 1,938 1,413 54,025 Additions c 12 193 92 2,597 2,894 Transfers 36 2,793 16 (2,845 ) – Disposals and adjustments d (82 ) (1,540 ) (119 ) (48 ) (1,789 ) Exchange differences (6 ) (35 ) (13 ) 1 (53 ) At 31 March 2018 1,262 50,783 1,914 1,118 55,077 Additions c 12 97 119 3,034 3,262 Transfers 13 2,988 18 (3,063 ) (44 ) Disposals and adjustments d (178 ) (1,943 ) (333 ) 102 (2,352 ) Exchange differences (2 ) (32 ) 4 – (30 ) At 31 March 2019 1,107 51,893 1,722 1,191 55,913 Accumulated depreciation At 31 March 2017 817 35,214 1,554 – 37,585 Charge for the year 57 2,213 121 – 2,391 Disposals and adjustments d (96 ) (1,613 ) (107 ) – (1,816 ) Exchange differences (5 ) (24 ) (10 ) – (39 ) At 31 March 2018 773 35,790 1,558 – 38,121 Charge for the year 51 2,236 105 – 2,392 Transfers 1 (4 ) – – (3 ) Disposals and adjustments d (104 ) (1,940 ) (296 ) – (2,340 ) Exchange differences (1 ) (30 ) 4 – (27 ) At 31 March 2019 720 36,052 1,371 – 38,143 Carrying amount At 31 March 2019 387 15,841 351 1,191 17,770 Engineering stores – – – 65 65 Total at 31 March 2019 387 15,841 351 1,256 17,835 At 31 March 2018 489 14,993 356 1,118 16,956 Engineering stores – – – 44 44 Total at 31 March 2018 489 14,993 356 1,162 17,000 a The carrying amount of the group’s property, plant and equipment includes an amount of £34m (2017/18: £53m) in respect of assets held under finance leases, comprising land and buildings of £34m (2017/18: £42m) and network infrastructure of £nil (2017/18: £11m). The depreciation expense on those assets in 2018/19 was £2m (2017/18: £10m), comprising land and buildings of £2m (2017/18: £3m) and network infrastructure of £nil (2017/18: £7m). b Other mainly comprises motor vehicles, computers and fixtures and fittings. c Net of grant deferral of £63m (2017/18: £74m net grant funding). d Fully depreciated assets in the group’s fixed asset registers were reviewed during the year, as part of the group’s annual asset verification exercise, and certain assets that were no longer in use have been written off, reducing cost and accumulated depreciation by £1.9bn (2017/18: £1.3bn). Disposals and adjustments also reflect the reclassification of the BT Centre property to held for sale (£89m), and £124m of adjustments resulting from changes in assumptions used in calculating lease-end obligations where the corresponding asset is capitalised.
Summary of Property Plant and Equipment	At 31 March 2019 £m 2018 £m The carrying amount of land and buildings, including leasehold improvements, comprised: Freehold 158 261 Leasehold 229 228 Total land and buildings 387 489

Programme rights (Tables)

Programme rights (Tables)	12 Months Ended
	Mar. 31, 2019
Disclosure Of Programme Rights [Abstract]
Summary of Programme Rights	Total £m At 1 April 2017 264 Additions 771 Amortisation (763 ) At 1 April 2018 272 Additions 879 Amortisation (841 ) At 31 March 2019 310

Trade and other receivables (Ta

Trade and other receivables (Tables)	12 Months Ended
	Mar. 31, 2019
Disclosure Of Trade And Other Receivables [Abstract]
Schedule of Trade and Other Receivables	At 31 March 2019 £m 2018 £m 2017 £m Current Trade receivables 1,732 1,741 1,774 Amounts owed by ultimate parent company 16 15 25 Prepayments a 698 1,103 733 Accrued income b 34 777 955 Deferred contract costs c 417 - - Other receivables d 341 393 373 3,238 4,029 3,860 At 31 March 2019 £m 2018 £m 2017 £m Non-current Other assets e 173 317 360 Deferred contract costs c 272 - - 445 317 360 a 2017/18 includes £325m b Accrued income recognised in prior years has been substantially reclassified to contract assets on adoption of IFRS 15. See notes 1 and 2. c Deferred contract costs arise following adoption of IFRS 15 on 1 April 2018. See notes 1 and 2. d Other receivables includes assets held for sale of £ nil. (2017/18: £nil, 2016/17: £22m). £89m assets held for sale as at 31 March 2019 are presented separately on the face of the balance sheet. e Other assets comprise prepayments and leasing debtors. Included in prior year comparatives are costs relating to the initial set-up, transition or transformation phase of long-term networked IT services contracts (2017/18: £145m, 2016/17: £163m), which are presented within deferred contract costs following adoption of IFRS 15.
Summary of Trade Receivables After Deducting Allowances for Doubtful Debts	Trade receivables are stated after deducting allowances for doubtful debts, as follows: 2019 £m 2018 £m 2017 £m At 1 April 375 303 195 Expense 95 129 211 Utilised (165 ) (61 ) (114 ) Exchange differences (6 ) 4 11 At 31 March 299 375 303
Summary of Trade Receivables Past Due and Not Specifically Impaired	Trade receivables are due as follows: Past due and not specifically impaired At 31 March Not past due £m Trade receivables specifically impaired net of provision £m Between 0 and 3 months £m Between 3 and 6 months £m Between 6 and 12 months £m Over 12 months £m Total £m 2019 1,229 34 371 42 40 16 1,732 2018 1,251 61 293 44 25 67 1,741 2017 1,184 146 292 17 41 94 1,774
Schedule of Trade Receivables Not Past Due and Accrued Income	Trade receivables not past due and accrued income are analysed below by customer-facing unit. Trade receivables not past due Accrued income At 31 March 2019 £m 2018 £m 2017 £m 2019 £m 2018 £m 2017 £m Consumer 457 — — 32 — — Enterprise 274 — — 2 — — Global Services 498 477 444 - 222 297 Openreach - 61 1 - 67 78 BT Consumer - 157 128 - 86 90 EE - 206 335 - 122 170 Business and Public Sector - 253 200 - 134 151 Wholesale and Ventures - 92 75 - 145 167 Other - 5 1 - 1 2 Total 1,229 1,251 1,184 34 777 955
Summary of Movement on Deferred Costs	The following table shows the movement on deferred costs: Deferred connection costs £m Deferred contract acquisition costs - commissions £m Deferred contract acquisition costs - dealer incentives £m Transition and transformation £m Total £m At 1 April 2018 7 85 416 161 669 Additions 15 76 446 32 569 Amortisation (14 ) (76 ) (426 ) (53 ) (569 ) Impairment - (5 ) (4 ) (1 ) (10 ) Other 23 6 - 1 30 At 31 March 2019 31 86 432 140 689

Trade and other payables (Table

Trade and other payables (Tables)	12 Months Ended
	Mar. 31, 2019
Trade And Other Payables [Abstract]
Summary of Trade and Other Payables	At 31 March 2019 £m 2018 £m 2017 £m Current Trade payables 4,141 3,991 4,205 Amounts owed to parent company 55 50 63 Amounts owed to ultimate parent company 1 - - Other taxation and social security 564 704 704 Other payables 368 428 648 Accrued expenses 630 492 382 Deferred income a 68 1,525 1,474 5,827 7,190 7,476 At 31 March 2019 £m 2018 £m 2017 £m Non-current Other payables b 873 871 885 Deferred income a 606 455 413 1,479 1,326 1,298 a Deferred income recognised in prior periods has substantially been reclassified to contract liabilities on adoption of IFRS 15, see notes 1 and 2. The remaining balance includes £ 51 m (2017/18: £132m, 2016/17: £71m) current and £ 586 m (2017/18: £404m, 2016/17: £375m) non-current liabilities relating to the Broadband Delivery UK programme, for which grants received by the group may be subject to re-investment or repayment depending on the level of take-up. b Other payables relate to operating lease liabilities and deferred gains on a 2001 sale and finance leaseback transaction.

Provisions (Tables)

Provisions (Tables)	12 Months Ended
	Mar. 31, 2019
Provisions [Abstract]
Details of Estimate of the Provisions	Restructuring £m Property £m Network ARO £m Network share £m Regulatory £m Litigation £m Other £m Total £m At 31 March 2017 11 292 83 50 479 69 177 1,161 Additions 4 37 2 – 51 6 33 133 Unwind of discount – 11 2 2 – – – 15 Utilised or released (2 ) (46 ) (16 ) (19 ) (210 ) (11 ) (32 ) (336 ) Transfers – – – – – – 85 85 Exchange differences (1 ) – – – – – (2 ) (3 ) At 31 March 2018 12 294 71 33 320 64 261 1,055 Additions – 84 102 2 58 3 66 315 Unwind of discount – 11 2 1 – – – 14 Utilised or released – (71 ) (13 ) (9 ) (196 ) (9 ) (109 ) (407 ) Transfers (12 ) 21 – – – 27 (7 ) 29 Exchange differences – – – – – (1 ) 1 – At 31 March 2019 – 339 162 27 182 84 212 1,006
Details of Provisions	At 31 March 2019 £m 2018 £m 2017 £m Analysed as: Current 424 603 625 Non-current 582 452 536 1,006 1,055 1,161

Retirement Benefit Plans (Table

Retirement Benefit Plans (Tables)	12 Months Ended
	Mar. 31, 2019
Disclosure Of Defined Benefit Plans [Abstract]
Summary of Retirement Benefit Plan	What h How m Defined Benefits n –cont r i –the r e –the d i d b Cont r i b n r n n r T h e h r e c n p r a u e r t p T h o r n c r i Defined e Benefits in a defined benefit plan are: – determined by the plan rules, dependent on factors such as age, years of service and pensionable pay –not n e T h e e r e p r b r f n r r T h n e e d o e w i o r c
Summary of Expense or Income from Retirement Benefit Arrangements Recognised in Income Statement	The expense or income arising from all group retirement benefit arrangements recognised in the group income statement is shown below. Year ended 31 March 2019 £m 2018 £m 2017 £m Recognised in the income statement before specific items – Service cost (including administration expenses & PPF levy): – defined benefit plans 135 376 281 – defined contribution plans 476 265 240 – Past service credit a – (17 ) – Subtotal 611 624 521 Recognised in the income statement as specific items (note 10) – Costs to close BT Pension Scheme and provide transition payments b 23 – – – Cost to equalise benefits between men and women due to guaranteed minimum pension (GMP) c 26 – – – Net interest expense on pensions deficit included in specific items 139 218 209 Subtotal 188 218 209 Total recognised in the income statement 799 842 730 a Relates to the removal of future indexation obligations following changes to the benefits provided under certain pension plans operating outside the UK in 2017/18 b c
Summary of Pension Obligation in Respect of Defined Benefit Plans Reported in Balance Sheet	The net pension obligation in respect of defined benefit plans reported in the group balance sheet is set out below. The prior year retirement benefit obligation has been restated as a result of a prior period accounting error, refer to note 2 for more details. 2019 2018 At 31 March Assets £m Present value of liabilities £m Deficit £m Assets £m Present value of liabilities (Restated) £m Deficit (Restated) £m BTPS 52,186 (58,855 ) (6,669 ) 49,894 (56,259 ) (6,365 ) EEPS 816 (997 ) (181 ) 763 (920 ) (157 ) Other plans a 362 (694 ) (332 ) 299 (624 ) (325 ) Retirement benefit obligation 53,364 (60,546 ) (7,182 ) 50,956 (57,803 ) (6,847 ) Adjustments due to effect of asset ceiling (IFRIC 14) – – Deferred tax asset 1,208 1,164 Net pension obligation (5,974 ) (5,683 ) a Included in the present value of obligations of other plans is £101m (2017/18: £97m) related to unfunded pension arrangements.
Summary of Movements on Pension Assets and Liabilities	The table below shows the movements on the pension assets and liabilities and shows where they are reflected in the financial statements. The prior year retirement benefit obligation has been restated as a result of a prior period accounting error, refer to note 2 for more details. Assets £m Liabilities £m Deficit £m At 31 March 2017 51,112 (60,200 ) (9,088 ) Service cost (including administration expenses and PPF levy) (67 ) (309 ) (376 ) Past service credit - 17 17 Interest on pension deficit 1,201 (1,419 ) (218 ) Included in the group income statement (577 ) Return on plan assets above the amount included in the group income statement 10 – 10 Actuarial gain arising from changes in financial assumptions a – 2,251 2,251 Actuarial loss arising from changes in demographic assumptions a – (697 ) (697 ) Actuarial gain arising from experience adjustments b – 120 120 Included in the group statement of comprehensive income 1,684 Regular contributions by employer 264 – 264 Deficit contributions by employer 872 – 872 Included in the group cash flow statement 1,136 Contributions by employees 2 (2 ) – Benefits paid (2,449 ) 2,449 – Foreign exchange 11 (13 ) (2 ) Other movements (2 ) At 31 March 2018 (Restated) 50,956 (57,803 ) (6,847 ) Service cost (including administration expenses and PPF levy) (49 ) (86 ) (135 ) Costs to close BT Pension Scheme (6) - (6 ) Cost to equalise benefits between men and women due to guaranteed minimum pension (GMP) - (26 ) (26 ) Interest on pension deficit 1,356 (1,495 ) (139 ) Included in the group income statement (306 ) Return on plan assets above the amount included in the group income statement 1,607 - 1,607 Actuarial loss arising from changes in financial assumptions a - (3,920 ) (3,920 ) Actuarial gain arising from changes in demographic assumptions a - 247 247 Actuarial loss arising from experience adjustments b - (36 ) (36 ) Included in the group statement of comprehensive income (2,102 ) Regular contributions by employer 43 - 43 Deficit contributions by employer 2,024 - 2,024 Included in the group cash flow statement 2,067 Contributions by employees 1 (1 ) - Benefits paid (2,564 ) 2,564 - Foreign exchange (4 ) 10 6 Other movements 6 At 31 March 2019 53,364 (60,546 ) (7,182 ) a The actuarial gain or loss arises from changes in the assumptions used to value the defined benefit liabilities at the end of the year compared with the assumptions used at the start of the year. This includes both financial assumptions, which are based on market conditions at the year end, and demographic assumptions such as life expectancy. b The actuarial loss or gain arising from experience adjustments on defined benefit liabilities represents the impact on the liabilities of differences between actual experience during the year compared with the assumptions made at the start of the year. Such differences might arise, for example, from members choosing different benefit options at retirement, actual salary increases being different from those assumed or actual benefit increases being different to the pension increase assumption.
Summary of Analysis of Membership	Analysis of BTPS Active members Deferred members Pensioners Total Sections A and B liabilities (£bn) a - 9.0 31.5 40.5 Section C liabilities (£bn) - 14.1 4.3 18.4 Total IAS 19 liabilities (£bn) - 23.1 35.8 58.9 Total number of members - b 83,000 205,000 288,000 a Sections A and B have been aggregated in this table as Section A members have typically elected to take Section B benefits at retirement. b At 31 March 2019 there are around 50 active members in the BTPS
Summary of Fair Value of Assets of BTPS Analysed by Asset Category	The fair value of the assets of the BTPS analysed by asset category are shown below. These are subdivided by assets that have a quoted market price in an active market and those that do not (such as investment funds). 2019 a 2018 a Total assets £bn of which quoted b £bn Total % Total assets £bn of which quoted b £bn Total % Growth Equities UK 0.5 0.4 1 0.5 0.5 1 Overseas developed 7.7 7.3 15 7.8 7.3 16 Emerging markets 1.1 1.1 2 0.5 0.4 1 Private Equity 1.5 – 3 1.9 – 4 Property UK 3.5 – 7 3.9 – 8 Overseas 1.1 – 2 1.2 – 2 Other growth assets Absolute Return c 1.2 – 2 1.5 – 3 Non Core Credit d 3.8 1.1 7 3.4 1.0 7 Mature Infrastructure 1.4 – 3 1.4 – 3 Liability matching Government bonds UK Index Linked 13.2 13.2 25 12.5 12.5 25 Investment grade credit Global 14.3 10.1 27 10.0 8.0 20 Cash, derivatives and other Cash balances 2.7 – 5 3.8 – 7 Longevity insurance contract e (0.7 ) – (1 ) (0.4 ) – (1 ) Other f 0.9 – 2 1.9 – 4 Total 52.2 33.2 100 49.9 29.7 100 a b Assets with a quoted price in an active market. c This allocation seeks to generate returns irrespective of the direction of markets. Managers within this allocation will typically manage their portfolios without close regard to a specific market benchmark. d This allocation includes a range of credit investments, including emerging market, sub-investment grade and unrated credit. The allocation seeks to exploit investment opportunities within credit markets using the expertise of a range of specialist investment managers. e The Trustee has hedged some of the Scheme’s longevity risk through a longevity insurance contract which was entered into in 2014. The value reflects experience to date on the contract from higher than expected deaths. This amount partly offsets a reduction which would be recognised in the Scheme’s liabilities over time. f Includes collateral posted in relation to derivatives held by the Scheme.
Summary of Approach Used to Set Key IAS 19 Assumptions	The table below summarises the approach used to set the key IAS 19 assumptions for the BTPS. Approa c s t h s Disc o IAS 19 requires that the discount rate is determined by reference to market yields at the reporting date on high quality corporate bonds. The currency and term of these should be consistent with the currency and estimated term of the pension obligations. The assumption is calculated by applying the projected BTPS benefit cash flows to a corporate bond yield curve constructed by our external actuary based on the yield on AA-rated corporate bonds. In setting the yield curve, judgement is required on the selection of appropriate bonds to be included in the universe and the approach used to then derive the yield curve. RPI o The RPI inflation assumption is set using an inflation curve derived from market yields on government bonds, weighted by projected BTPS benefit cash flows, and making an adjustment for an inflation risk premium (to reflect the extra premium paid by investors for inflation protection), which is currently assumed to be 20bps. CPI o CPI P k i i Pensi o n Benefits are assumed to increase in line with the RPI or CPI inflation assumptions, based on the relevant index for increasing benefits, as prescribed by the rules of the BTPS and summarised above. Lo n v The longevity assumption takes into account: – the actual mortality experience of the BTPS pensioners, based on a formal review conducted at the 2014 triennial funding valuation – future improvements in longevity based on a model published by UK actuarial profession’s Continuous Mortality Investigation (using the CMI 2017 Mortality Projections model with a 1.25% per year long-term improvement parameter)
Summary of Key Financial Assumptions Used to Measure Liabilities of BTPS	The key financial assumptions used to measure the liabilities of the BTPS are shown below. Nominal rates (per year) Real rates (per year) a At 31 March 2019 % 2018 % 2017 % 2019 % 2018 % 2017 % Rate used to discount liabilities 2.35 2.65 2.40 (0.87 ) (0.44 ) (0.78 ) Inflation – increase in RPI 3.25 3.10 3.20 – – – Inflation – increase in CPI 2.25 b 2.00 c 2.00 d (1.0) b (1.1) c (1.2) d a The real rate is calculated relative to RPI inflation. b Assumed to be 0.1% lower until 31 March 2023. c Assumed to be 0.1% higher until 31 March 2023. d Assumed to be 0.5% higher until 31 March 2019
Summary of Average Life Expectancies for Members Aged Sixty	B a h e a pe a o m b g 6 a f o At 31 March 2019 Number of years 2018 Number of years Male in lower pay bracket 25.7 25.8 Male in medium pay bracket 27.0 27.1 Male in higher pay bracket 28.5 28.5 Female in lower pay bracket 28.5 28.5 Female in higher pay bracket 28.7 28.7 Average improvement for a member retiring at age 60 in 10 years' time 0.7 0.7 T h a g l p e n a o n h a a d a o e e 6 a o g a l w Number of years from valuation date June 2017 assumptions June 2014 assumptions Male in lower pay bracket 25.9 26.1 Male in medium pay bracket 27.2 27.5 Male in high pay bracket 28.6 29.0 Female in lower pay bracket 28.6 28.9 Female in high pay bracket 28.9 29.2 Average improvement for a member retiring at age 60 in 10 years’ time 0.9 1.3
Summary of Assessed Potential Negative Impact of Key Risk	B T r Scenario 1-in-20 events 2019 2018 1. Fall in discount rate a 1.1 % 1.1 % 2. Increase to inflation rate b 0.7 % 0.7 % 3. Fall in equity markets c 30.0 % - 4. Increase to life expectancy 1.25 years 1.35 years a Scenario assumes a fall in the yields on both government and corporate bonds. b Assuming RPI, CPI, pension increases and salary increases all increase by the same amount. c Scenario ignores any potential benefit from derivatives held by the scheme.
Summary of Two Most Recent Triennial Valuations	T h l t o o e e n a u n o b e o June 2017 valuation £bn June 2014 valuation £bn BTPS liabilities (60.4 ) (47.2 ) Market value of BTPS assets 49.1 40.2 Funding deficit (11.3 ) (7.0 ) Percentage of accrued benefits covered by BTPS assets at valuation date 81.3% 85.2% Percentage of accrued benefits on a solvency basis covered by the BTPS assets at the valuation date 62.2% 63.0%
Summary of Prudent Long-Term Assumptions	These valuations were determined using the following prudent long-term assumptions. Nominal rates (per year) Real rates (per year) a June 2017 valuation % June 2014 valuation % June 2017 valuation % June 2014 valuation % Average single equivalent discount rate 2.6 4.5 (0.8 ) 1.0 Average long-term increase in RPI 3.4 3.5 – – Average long-term increase in CPI 2.4 2.5 (1.0 ) (1.0 ) a T he r e al ra t e is c alcu l ated relat i ve to RPI i n flati o n and is s h own as a com p arat o r .
Summary of Payments Made to BTPS	Payments made to the BTPS Year ended 31 March 2019 £m 2018 £m Ordinary contributions 33 248 Deficit contributions 2,000 850 Total contributions in the year 2,033 1,098
Schedule of Future Deficit Payment to BTPS	BT h u e a d e e i w h l e w Year to 31 March 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 Deficit contribution (£m) 1,250 a 900 b 900 c 907 907 907 907 907 907 907 907 a payable by 30 June 2019. b £400m payable by 30 June 2020. c £200m payable by 30 June 2021.

Share-based payments (Tables)

Share-based payments (Tables)	12 Months Ended
	Mar. 31, 2019
Share Based Payments [Abstract]
Summary of Plans and Analysis of Total Charge by Type of Award	Year ended 31 March 2019 £m 2018 £m 2017 £m Employee Saveshare Plans 38 42 40 Executive Share Plans: Incentive Share Plan (ISP) 6 16 – Deferred Bonus Plan (DBP) 6 4 9 Retention Share Plan (RSP) 17 21 8 Other plans – 1 – 67 84 57
Movements in Employee Saveshare Options	Movements in Employee Saveshare options are shown below. Movement in the number of share options Weighted average exercise price Year ended 31 March 2019 millions 2018 millions 2017 millions 2019 pence 2018 pence 2017 pence Outstanding at 1 April 175 189 197 306 313 287 Granted 80 69 44 175 250 362 Forfeited (44 ) (41 ) (18 ) 298 328 345 Exercised (1 ) (30 ) (33 ) 247 169 208 Expired (20 ) (12 ) (1 ) 294 353 345 Outstanding at 31 March 190 175 189 254 306 313 Exercisable at 31 March – – – 249 320 237
Summarises Information Relating to Options Outstanding and Exercisable Under Employee Saveshare Plans	The following table summarises information relating to options outstanding and exercisable under Employee Saveshare plans at 31 March 2018. Normal dates of vesting and exercise (based on calendar years) Exercise price per share Weighted average exercise price Number of outstanding options millions Weighted average remaining contractual life 2019 319p – 397p 333 p 40 10 months 2020 243p – 376p 305 p 34 22 months 2021 243p 232 p 43 34 months 2022 170p 243 p 29 46 months 2023 170p 43 58 months Total 254 p 189 34 months
Movements in Executive Share Plan Awards	Movements in executive share plan awards during 2017/18 are shown below: Number of shares (millions) ISP DBP RSP Total At 31 March 2018 54 6 12 72 Awards granted 33 4 7 44 Awards vested – (1 ) (7 ) (8 ) Awards lapsed (18 ) (1 ) (1 ) (20 ) Dividend shares reinvested 5 5 At 31 March 2019 74 8 11 93
Summary of Fair Values and Key Assumptions Used for Valuing Grants Made Under Employee Saveshare Plans and ISP	The following table summarises the fair values and key assumptions used for valuing grants made under the Employee Saveshare plans and ISP in 2018/19, 2017/18 and 2016/17.

Investments (Tables)

Investments (Tables)	12 Months Ended
	Mar. 31, 2019
Disclosure Of Investments [Abstract]
Summary of Investments	At 31 March 2019 £m 2018 £m 2017 £m Non-current assets Fair value through other comprehensive income 48 – – Available-for-sale – 46 37 Amounts owed by ultimate parent company 3,029 2,983 1,371 Amounts owed by parent company 10,436 10,318 10,191 Fair value through profit or loss 6 7 7 13,519 13,354 11,606 Current assets Fair value through other comprehensive income – – – Available-for-sale – 2,575 1,437 Amounts owed by ultimate parent company 61 34 28 Amounts owed by parent company 211 168 192 Investment held at amortised cost 3,214 – – Loans and receivables – 447 83 3,486 3,224 1,740
Fair Value Hierarchy of Investments	Fair value hierarchy At 31 March 2019 Level 1 £m Level 2 £m Level 3 £m Total held at fair value £m Non-current and current investments Fair value through other comprehensive income 38 – 10 48 Fair value through profit or loss 6 – – 6 Total 44 – 10 54 At 31 March 2018 Level 1 £m Level 2 £m Level 3 £m Total held at fair value £m Non-current and current investments Available-for-sale 32 2,575 14 2,621 Fair value through profit or loss 7 – – 7 Total 39 2,575 14 2,628 At 31 March 2017 Level 1 £m Level 2 £m Level 3 £m Total held at fair value £m Non-current and current investments Available-for-sale 21 1,437 16 1,474 Fair value through profit or loss 7 – – 7 Total 28 1,437 16 1,481

Cash and cash equivalents (Tabl

Cash and cash equivalents (Tables)	12 Months Ended
	Mar. 31, 2019
Cash And Cash Equivalents [Abstract]
Summary of Cash and Cash Equivalents	At 31 March 2019 £m 2018 £m 2017 £m Cash at bank and in hand 493 439 467 Cash equivalents US deposits 3 26 32 UK deposits 1,132 31 1 Other deposits 36 25 26 Total cash equivalents 1,171 82 59 Total cash and cash equivalents 1,664 521 526 Bank overdrafts (note 23) (72 ) (29 ) (17 ) Cash and cash equivalents per the cash flow statement 1,592 492 509

Loans and other borrowings (Tab

Loans and other borrowings (Tables)	12 Months Ended
	Mar. 31, 2019
Loans And Other Borrowings [Abstract]
Summary of Key Components of External Gross Debt	The table below shows the key components of external gross debt and of the increase of £2,737m this year. At 1 April 2018 £m Issuance/ (maturities) £m Fair value movements £m Foreign exchange £m Transfer to within one year £m Accrued interest movements £m At 31 March 2019 £m Debt due within one year a 2,281 (1,423 ) (8 ) (97 ) 1,281 66 2,100 Debt due after one year 11,994 3,972 (11 ) (102 ) (1,111 ) 34 14,776 Cash flows from Derivatives related to net debt – 124 – – (124 ) – – Overdrafts – 46 – – (46 ) – – Impact of cross-currency swaps b (874 ) – – 182 – (9 ) (701 ) Removal of the accrued interest and fair value adjustments c (226 ) – 19 – – (56 ) (263 ) External gross debt 13,175 2,719 - (17 ) - 35 15,912 a Including accrued interest and bank overdrafts . b Translation of debt balances at swap rates where hedged by cross currency swaps. c Removal of accrued interest applied to reflect the effective interest rate method and removal of fair value adjustments.
Summary of Reconciliation From Most Directly Comparable IFRS Measure to Net Debt	The table below gives the details of the listed bonds and other debt. At 31 March 2019 £m 2018 £m 2017 £m 6.625% £500m bond due June 2017 a - - 526 5.95% US$1,100m bond due January 2018 a - - 891 3.25% €600m bond due August 2018 a - 541 539 2.35% US$800m bond due February 2019 a - 572 642 4.38% £450m bond due March 2019 - 455 460 1.125% €1,000m bond due June 2019 a 869 883 863 8.625% £300m bond due March 2020 300 300 300 0.625% €1,500m bond due March 2021 a 1,289 1,309 1,282 0.5% €575m bond due June 2022 a 495 502 – 1.125% €1,100m bond due March 2023 a 946 961 942 0.875% €500m bond due September 2023 a 430 - - 4.5% US$675m bond due December 2023 a 524 - - 1% €575m bond due June 2024 a 498 506 – 1% €1,100m bond due November 2024 a 943 959 – 3.50% £250m index linked bond due April 2025 433 419 403 1.75% €1,300m bond due March 2026 a 1,118 1,137 1,113 1.5% €1,150m bond due June 2027 a 993 1,009 – 2.125% €500m bond due September 2028 a 433 - - 5.125% US$700m bond due December 2028 a 542 - - 5.75% £600m bond due December 2028 710 721 731 9.625% US$2,670m bond due December 2030 a b 2,096 1,943 2,191 3.125% £500m bond due November 2031 502 502 – 3.64% £330m bond due June 2033 339 - - 1.613% £330m Indexed linked bond due June 2033 340 - - 6.375% £500m bond due June 2037 a 522 522 522 3.883% £330m bond due June 2039 340 - - 1.739% £330m Indexed linked bond due June 2039 340 - - 3.924% £340m bond due June 2042 350 - - 1.774% £340m Indexed linked bond due June 2042 351 - - 3.625% £250m bond due November 2047 250 250 – Total listed bonds 15,953 13,491 11,405 Finance leases 206 223 229 2.21% £350m bank loan due December 2017 – – 352 Other loans 645 532 710 Bank overdrafts (note 22) 72 29 17 Amounts due to ultimate company c 2,101 1,061 1,183 Total other loans and borrowings 2,818 1,622 2,262 Total loans and borrowings 18,977 15,336 13,896 a Designated in a cash flow hedge relationship. b The interest rate payable on this bond attracts an additional 0.25% for a downgrade by one credit rating by either Moody’s or Standard & Poor’s to the group’s senior unsecured debt below A3/A–respectively. In addition, if Moody’s or Standard & Poor’s subsequently increase the ratings then the interest rate will be decreased by 0.25% for each rating category upgrade by each rating agency. In no event will the interest rate be reduced below the minimum rate reflected in the above table. c Amounts due to ultimate parent company are denominated in sterling and incur a floating rate of interest based on LIBOR.
Summary of Loans and Other Borrowings	L o n o At 31 March 2019 £m 2018 £m 2017 £m Current liabilities Listed bonds 1,367 1,702 1,539 Finance leases 16 18 15 Bank loans – – 352 Other loans and bank overdrafts a 717 561 726 Amounts due to ultimate parent company 1,040 17 159 Total current liabilities 3,140 2,298 2,791 Non-current liabilities Listed bonds 14,586 11,789 9,866 Finance leases 190 205 214 Other loans – – 1 Amounts due to ultimate parent company 1,061 1,044 1,024 Total non-current liabilities 15,837 13,038 11,105 Total 18,977 15,336 13,896 a Incl u des c olla t eral r e cei v ed on sw a ps of £638m (2 0 17/ 18 : £525 m , 20 16 /17: £702 m).
Summary of Principal Repayments of Loans and Other Borrowings	The p n p a e a n o a n n o o g a e ge a e o £17,970 2 2 £12,138 a n e a d u a l w 2019 2018 2017 At 31 March Carrying amount £m Effect of hedging and interest £m Principal repayments at hedged rates £m Carrying amount £m Effect of hedging and interest £m Principal repayments at hedged rates £m Carrying amount £m Effect of hedging and interest £m Principal repayments at hedged rates £m Within one year, or on demand 3,140 (307 ) 2,833 2,289 (308 ) 1,981 2,791 (523 ) 2,268 Between one and two years 1,309 (133 ) 1,176 1,192 (66 ) 1,126 1,614 (197 ) 1,417 Between two and three years 15 - 15 1,332 (154 ) 1,178 1,166 (43 ) 1,123 Between three and four years 1,463 (89 ) 1,374 18 – 18 1,295 (121 ) 1,174 Between four and five years 964 33 997 1,489 (111 ) 1,378 12 – 12 After five years 12,036 (461 ) 11,575 8,943 (405 ) 8,538 6,868 (724 ) 6,144 Total due for repayment after more than one year 15,787 (650 ) 15,137 12,974 (736 ) 12,238 10,955 (1,085 ) 9,870 Total repayments 18,927 (957 ) 17,970 15,263 (1,044 ) 14,219 13,746 (1,608 ) 12,138 Fair value adjustments 50 73 150 Total loans and other borrowings 18,977 15,336 13,896
Summary of Obligations Under Finance Leases	O b g n d a l e n l a l w 2019 2018 2017 2019 2018 2017 Minimum lease payments Repayment of outstanding lease obligations At 31 March £m £m £m £m Amounts payable under finance leases: Due within one year 29 33 29 16 18 14 Between two to five years 109 122 102 66 71 50 After five years 159 193 237 120 130 165 297 348 368 202 219 229 Less: future finance charges (95 ) (129 ) (139 ) – – – Fair value adjustments for purchase price adjustment 4 4 – 4 4 – Total finance lease obligations 206 223 229 206 223 229

Finance expense (Tables)

Finance expense (Tables)	12 Months Ended
	Mar. 31, 2019
Disclosure Of Finance Income Expense [Abstract]
Summary of Finance Expense and Income	Year ended 31 March 2019 £m 2018 £m 2017 £m Finance expense Interest on: Financial liabilities at amortised cost and associated derivatives 582 478 567 Finance leases 13 16 15 Derivatives - 14 12 Fair value movements on derivatives not in a designated hedge relationship (3 ) 1 (2 ) Reclassification of cash flow hedge from other comprehensive income 45 34 (1 ) Unwinding of discount on provisions 14 15 16 Interest payable on ultimate parent company borrowings 43 18 25 Total finance expense before specific items 694 576 632 Specific items (note 10) 139 218 210 Total finance expense 833 794 842 Year ended 31 March 2019 £m 2018 £m 2017 £m Finance income Interest on available-for-sale investments - 5 6 Interest on loans and receivables 34 7 7 Interest income on loans to immediate and ultimate parent company 272 203 219 Total finance income 306 215 232 Year ended 31 March 2019 £m 2018 £m 2017 £m Net finance expense before specific items 388 361 400 Specific items (note 10) 139 218 210 Net finance expense 527 579 610

Financial instruments and ris_2

Financial instruments and risk management (Tables)	12 Months Ended
	Mar. 31, 2019
Text Block1 [Abstract]
Summary of Currency and Interest Rate Profile of Loans and Borrowings	The table below reflects the currency and interest rate profile of our loans and borrowings after the impact of hedging. 2019 2018 2017 At 31 March Fixed rate interest £m Floating rate interest £m Total £m Fixed rate interest £m Floating rate interest £m Total £m Fixed rate interest £m Floating rate interest £m Total £m Sterling 13,556 3,825 17,381 11,990 1,720 13,710 9,633 1,864 11,497 Euro – 589 589 – 509 509 – 641 641 Total 13,556 4,414 17,970 11,990 2,229 14,219 9,633 2,505 12,138 Ratio of fixed to floating 75 % 25 % 100% 84 % 16 % 100% 79 % 21 % 100% Weighted average effective fixed interest rate – sterling 4.0 % 4.4 % 4.9 %
Summary of Impact on Equity, Before Tax, of a 1% Increase in Interest	The impact on equity, before tax, of a 1% increase in interest rates and a 10% strengthening in sterling against other currencies is as detailed below: At 31 March 2019 £m Increase (reduce) 2018 £m Increase (reduce) 2017 £m Increase (reduce) Sterling interest rates 672 628 554 US dollar interest rates (350 ) (267 ) (348 ) Euro interest rates (399 ) (401 ) (229 ) Sterling strengthening (219 ) (236 ) (269 )
Summary of Credit Ratings	BT Group plc’s credit ratings were as detailed below: 2019 2018 2017 At 31 March Rating Outlook Rating Outlook Rating Outlook Rating agency Moody’s Baa2 Stable Baa2 Stable Baa1 Negative Standard & Poor’s BBB Stable BBB+ Negative BBB+ Negative
Remaining Contractually-Agreed Cash Flows Including Interest Payable for Non-Derivative Financial Liabilities on Undiscounted Basis	The following table provides an analysis of the remaining contractually-agreed cash flows including interest payable for our non- derivative financial liabilities on an undiscounted basis, which therefore differs from both the carrying value and fair value. Non-derivative financial liabilities At 31 March 2019 Loans and other borrowings £m Interest on loans and other borrowings £m Trade and other payables £m Provisions £m Total £m Due within one year 2,883 584 5,195 39 8,701 Between one and two years 1,309 528 – 33 1,870 Between two and three years 15 520 – 35 570 Between three and four years 1,463 519 – 14 1,996 Between four and five years 964 505 – 12 1,481 After five years 12,036 4,345 – 127 16,508 18,670 7,001 5,195 260 31,126 Interest payments not yet accrued – (6,744 ) – – (6,744 ) Fair value adjustment 50 – – – 50 Impact of discounting – – – (29 ) (29 ) Carrying value on the balance sheet ab 18,720 257 5,195 231 24,403 Non-derivative financial liabilities At 31 March 2018 Loans and other borrowings £m Interest on loans and other borrowings £m Trade and other payables £m Provisions £m Total £m Due within one year 2,120 468 4,961 54 7,603 Between one and two years 1,192 421 – 34 1,647 Between two and three years 1,332 381 – 25 1,738 Between three and four years 18 374 – 43 435 Between four and five years 1,489 372 – 19 1,880 After five years 8,943 3,300 – 197 12,440 15,094 5,316 4,961 372 25,743 Interest payments not yet accrued – (5,147 ) – – (5,147 ) Fair value adjustment 73 – – – 73 Impact of discounting – – – (72 ) (72 ) Carrying value on the balance sheet ab 15,167 169 4,961 300 20,597 Non-derivative financial liabilities At 31 March 2017 Loans and other borrowings £m Interest on loans and other borrowings £m Trade and other payables £m Provisions £m Total £m Due within one year 2,602 532 5,298 62 8,494 Between one and two years 1,614 415 – 41 2,070 Between two and three years 1,166 364 – 21 1,551 Between three and four years 1,295 327 – 18 1,640 Between four and five years 12 319 – 17 348 After five years 6,868 2,726 – 310 9,904 13,557 4,683 5,298 469 24,007 Interest payments not yet accrued – (4,494 ) – – (4,494 ) Fair value adjustment 150 – – – 150 Impact of discounting – – – (177 ) (177 ) Carrying value on the balance sheet ab 13,707 189 5,298 292 19,486 a Foreign currency-related cash flows were translated at closing rates as at the relevant reporting date. Future variable interest rate cash flows were calculated using the most recent rate applied at the relevant balance sheet date. b The carrying amount of trade receivables and other payables excludes £1,479m (2017/18: £1,326m, 2016/17: £1,298m) of non-current trade and other payables and £632m (2017/18: £2,229m, 2016/17: £2,178m) of other taxation and social security and deferred income.
Disclosure Of Maturity Analysis For Derivative Financial Liabilities Explanatory	The following table provides an analysis of the contractually agreed cash flows in respect of the group’s derivative financial instruments. Cash flows are presented on a net or gross basis in accordance with the settlement arrangements of the instruments. Derivatives – Analysed by earliest payment date a Derivatives – Analysed based on holding instrument to maturity Derivative financial liabilities At 31 March 2019 Net settled £m Gross settled outflows £m Gross settled inflows £m Total £m Net settled £m Gross settled outflows £m Gross settled inflows £m Total £m Due within one year 167 1,007 (950 ) 224 82 1,007 (950 ) 139 Between one and two years 128 541 (489 ) 180 77 541 (489 ) 129 Between two and three years 131 131 (96 ) 166 71 131 (96 ) 106 Between three and four years 163 633 (591 ) 205 71 633 (591 ) 113 Between four and five years 207 1,095 (1,042 ) 260 71 1,095 (1,042 ) 124 After five years 43 3,790 (3,660 ) 173 467 3,790 (3,660 ) 597 Total b 839 7,197 (6,828 ) 1,208 839 7,197 (6,828 ) 1,208 Derivatives – Analysed by earliest payment date a Derivatives – Analysed based on holding instrument to maturity Derivative financial liabilities At 31 March 2018 Net settled £m Gross settled outflows £m Gross settled inflows £m Total £m Net settled £m Gross settled outflows £m Gross settled inflows £m Total £m Due within one year 140 587 (547 ) 180 91 587 (547 ) 131 Between one and two years 135 183 (166 ) 152 91 183 (166 ) 108 Between two and three years 156 442 (446 ) 152 85 69 (47 ) 107 Between three and four years 143 52 (29 ) 166 80 68 (47 ) 101 Between four and five years 161 52 (29 ) 184 80 68 (47 ) 101 After five years 291 2,234 (2,149 ) 376 599 2,575 (2,512 ) 662 Total b 1,026 3,550 (3,366 ) 1,210 1,026 3,550 (3,366 ) 1,210 Derivatives – Analysed by earliest payment date a Derivatives – Analysed based on holding instrument to maturity Derivative financial liabilities At 31 March 2017 Net settled £m Gross settled outflows £m Gross settled inflows £m Total £m Net settled £m Gross settled outflows £m Gross settled inflows £m Total £m Due within one year 291 582 (576 ) 297 92 582 (576 ) 98 Between one and two years 296 1,139 (1,097 ) 338 92 1,139 (1,097 ) 134 Between two and three years 198 — — 198 92 — — 92 Between three and four years 114 — — 114 88 — — 88 Between four and five years 104 — — 104 83 — — 83 After five years 123 — — 123 679 — — 679 Total b 1,126 1,721 (1,673 ) 1,174 1,126 1,721 (1,673 ) 1,174 a Certain derivative financial instruments contain break clauses whereby either the group or bank counterparty can terminate the swap on certain dates and the mark to market position is settled in cash. b
Summary of Maximum Credit Risk Exposure of Financial Assets	The maximum credit risk exposure of the group’s financial assets at the balance sheet date is as follows: At 31 March Notes 2019 £m 2018 £m 2017 £m Derivative financial assets 1,592 1,509 2,246 Investments 21 17,005 16,578 13,346 Trade and other receivables c 16 1,782 2,533 2,754 Contract assets 6 1,602 — — Cash and cash equivalents 22 1,664 521 526 23,645 21,141 18,872 c The carrying amount excludes £445m (2017/18: £317m, 2016/17: £360m) of non-current trade and other receivables which relate to non-financial assets, and £1,456m (2017/18: £1,496m, 2016/17: £1,106m) of prepayments, deferred contract costs and other receivables.
Summary of Credit Quality and Credit Concentration of Cash Equivalents, Current Asset Investments and Derivative Financial Assets	The credit quality and credit concentration of cash equivalents, current asset investments and derivative financial assets are detailed in the tables below. Where the opinion of Moody’s and S&P differ, the lower rating is used. Moody’s/S&P credit rating of counterparty 2019 £m 2018 £m 2017 £m Aa2/AA and above 2,522 2,575 1,444 Aa3/AA– 1,376 313 208 A1/A+ a 1,145 651 952 A2/A a 649 628 370 A3/A– a 50 180 204 Baa1/BBB+ a 75 59 561 Baa2/BBB and below a 160 207 86 5,977 4,613 3,825 a We hold cash collateral of £638m (2017/18: £492m, 2016/17: £702m) in respect of derivative financial assets with certain counterparties.
Summary of Offsetting of Financial Assets and Liabilities	The table below shows our financial assets and liabilities that are subject to offset in the group’s balance sheet and the impact of enforceable master netting or similar agreements. Related amounts not set off in the balance sheet Financial assets and liabilities At 31 March 2019 Amounts presented in the balance sheet £m Right of set off with derivative counterparties £m Cash collateral £m Net amount £m Derivative financial assets 1,592 (802 ) (638 ) 152 Derivative financial liabilities (940 ) 802 90 (48 ) Total 652 – (548 ) 104 Related amounts not set off in the balance sheet Financial assets and liabilities At 31 March 2018 Amounts presented in the balance sheet £m Right of set off with derivative counterparties £m Cash collateral £m Net amount £m Derivative financial assets 1,509 (754 ) (492 ) 263 Derivative financial liabilities (837 ) 754 60 (23 ) Total 672 – (432 ) 240 Related amounts not set off in the balance sheet Financial assets and liabilities At 31 March 2017 Amounts presented in the balance sheet £m Right of set off with derivative counterparties £m Cash collateral £m Net amount £m Derivative financial assets 2,246 (693 ) (702 ) 851 Derivative financial liabilities (903 ) 693 64 (146 ) Total 1,343 – (638 ) 705
Summary of Derivative Financial Instruments are Held at Fair Value on Balance Sheet	The fair values of outstanding swaps and foreign exchange contracts are estimated using discounted cash flow models and market rates of interest and foreign exchange at the balance sheet date. At 31 March 2019 Current asset £m Non-current asset £m Current liability £m Non-current liability £m Designated in a cash flow hedge 102 1,228 40 689 Other 9 253 8 203 Total derivatives 111 1,481 48 892 At 31 March 2018 Current asset £m Non-current asset £m Current liability £m Non-current liability £m Designated in a cash flow hedge 187 1,061 41 587 Other 10 251 9 200 Total derivatives 197 1,312 50 787 At 31 March 2017 Current asset £m Non-current asset £m Current liability £m Non-current liability £m Designated in a cash flow hedge 417 1,508 25 616 Other 11 310 9 253 Total derivatives 428 1,818 34 869
Summary of Items Designated As Hedging Instruments	The amounts related to items designated as hedging instruments were as follows: Hedged items At 31 March 2019 Notional principal £m Asset £m Liability £m Balance in cash flow hedge related reserves (gain)/loss £m Fair value (gain)/loss recognised in OCI £m Amount recycled from cash flow hedge related reserves to P&L £m Sterling, euro and US dollar denominated borrowings a 13,518 1,311 (702 ) (48 ) (130 ) (19 ) US dollar step up interest on US denominated borrowings b 145 3 (1 ) (38 ) (13 ) 4 Foreign currency purchases, principally denominated in US dollar, euro and Asia Pacific currencies c 1,821 16 (26 ) (13 ) (33 ) 33 Total cash flow hedges 15,484 1,330 (729 ) (99 ) (176 ) 18 Deferred tax – – 15 Derivatives not in a designated hedge relationship 262 (211 ) – Carrying value on the balance sheet 1,592 (940 ) (84 ) Hedged items At 31 March 2018 d Notional principal £m Asset £m Liability £m Balance in cash flow hedge related reserves (gain)/loss £m Fair value (gain)/loss recognised in OCI £m Amount recycled from cash flow hedge related reserves to P&L £m Sterling, euro and US dollar denominated borrowings a 12,504 1,222 (608 ) 101 347 (333 ) US dollar step up interest on US denominated borrowings b 143 – (6 ) (29 ) 13 3 Foreign currency purchases, principally denominated in US dollar, euro and Asia Pacific currencies c 1,989 26 (14 ) (13 ) 8 53 Total cash flow hedges 14,636 1,248 (628 ) 59 368 (277 ) Deferred tax – – (22 ) Derivatives not in a designated hedge relationship 261 (209 ) – Carrying value on the balance sheet 1,509 (837 ) 37 Hedged items At 31 March 2017 d Notional principal £m Asset £m Liability £m Balance in cash flow hedge related reserves (gain)/loss £m Fair value (gain)/loss recognised in OCI £m Amount recycled from cash flow hedge related reserves to P&L £m Sterling, euro and US dollar denominated borrowings a 10,041 1,845 (621 ) 87 (800 ) 938 US dollar step up interest on US denominated borrowings b 146 5 (2 ) (45 ) (21 ) 4 Foreign currency purchases, principally denominated in US dollar, euro and Asia Pacific currencies c 2,327 75 (18 ) (74 ) (63 ) (4 ) Total cash flow hedges 12,514 1,925 (641 ) (32 ) (884 ) 938 Deferred tax – – (95 ) Derivatives not in a designated hedge relationship 321 (262 ) – Carrying value on the balance sheet 2,246 (903 ) (127 ) a Sterling, euro and US dollar denominated borrowings are hedged using cross currency swaps and interest rate swaps. Amounts recycled to the profit and loss are presented within other operating costs and finance expense b US dollar step up interest on US denominated borrowings are hedged using forward currency contracts. Amounts recycled to profit and loss are presented within finance expense. c Foreign currency purchases, principally denominated in US dollar, euro and Asia Pacific currencies are hedged using forward currency contracts. Amounts recycled to profit and loss in respect of these items are presented within cost of sales and other operating costs. d We have presented comparatives to this information, now required by IFRS7 following the adoption of IFRS9, for 31 March 2018 and 31 March 2017.

Other reserves (Tables)

Other reserves (Tables)	12 Months Ended
	Mar. 31, 2019
Disclosure Of Reserves Within Equity [Abstract]
Summary of Other Reserves	Other comprehensive income Cash flow reserve a £m Fair value reserve b £m Cost of hedging reserve c £m Translation reserve d £m Merger and other reserves £m Total £m At 1 April 2016 173 16 – 345 858 1,392 Exchange differences e – – – 227 – 227 Net fair value gain on cash flow hedges 884 – – – – 884 Movements in relation to cash flow hedges recognised in income and expense (938 ) – – – – (938 ) Fair value movement on available-for-sale assets – (3 ) – – – (3 ) Tax recognised in other comprehensive income 8 – – 21 – 29 At 1 April 2017 127 13 – 593 858 1,591 Exchange differences e – – – (188 ) – (188 ) Net fair value gain on cash flow hedges (368 ) – – – – (368 ) Movements in relation to cash flow hedges recognised in income and expense 277 – – – – 277 Fair value movement on available-for-sale assets – 11 – – – 11 Tax recognised in other comprehensive income 10 – – (9 ) – 1 Transfer to realised profit (83 ) – – – – (83 ) At 31 March 2018 (37 ) 24 – 396 858 1,241 Transfer to cost of hedging reserve 81 – (81 ) – – – At 31 March 2018 44 24 (81 ) 396 858 1,241 Exchange differences e – – – 64 – 64 Net fair value loss on cash flow hedges 168 – 8 – – 176 Movements in relation to cash flow hedges recognised in income and expense (31 ) – 13 – – (18 ) Fair value movement on assets at fair value through other comprehensive income – 3 – – – 3 Tax recognised in other comprehensive income (37 ) – – (4 ) – (41 ) Transfer to realised profit – – – – – – At 31 March 2019 144 27 (60 ) 456 858 1,425 a The cash flow reserve is used to record the effective portion of the cumulative net change in the fair value of cash flow hedging instruments related to hedged transactions that have not yet occurred. Amounts ‘recognised in income and expense’ include a net charge to the cash flow reserve of £30m (2017/18: credit of £295m, 2016/17: charge of £941m) relating to fair value movements on derivatives. The items generating these foreign exchange movements are in designated cash flow hedge relationships. b The fair value reserve (2018, 2017: available-for-sale reserve) is used to record the cumulative fair value gains and losses on assets classified as fair value through other comprehensive income (2018, 2017: available-for-sale financial assets). The cumulative gains and losses are recycled to the income statement on disposal of the assets. c The cost of hedging reserve reflects the gain or loss on the portion excluded from the designated hedging instrument that relates to the currency basis element of our cross currency swaps. It is initially recognised in other comprehensive income and accounted for similarly to gains or losses in the cash flow reserve. d The translation reserve is used to record cumulative translation differences on the assets and liabilities of foreign operations. The cumulative translation differences are recycled to the income statement on disposal of the foreign operation. e Excludes £(2)m (2017/18: £1m, 2016/17: £10m) of exchange differences in relation to retained earnings attributed to non-controlling interests .

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Mar. 31, 2019
Disclosure Of Transactions Between Related Parties [Abstract]
Balances with Parent and Ultimate Parent Companies and Finance Income or Expense	A summary of the balances with the parent and ultimate parent companies and the finance income or expense arising in respect of these balances is set out below: 2019 2018 2017 Notes Asset (liability) at 31 March £m Finance income (expense) £m Asset (liability) at 31 March £m Finance income (expense) £m Asset (liability) at 31 March £m Finance income (expense) £m Amounts owed by (to) parent company Loan facility – non-current assets investments 21,24 10,436 211 10,318 169 10,191 191 Loan facility – current asset investments 21 211 n/a 168 n/a 192 n/a Trade and other payables 17 (55 ) n/a (50 ) n/a (63 ) n/a Amounts owed by (to) ultimate parent company a Non-current assets investments 21,24 3,029 61 2,983 34 1,371 28 Non-current liabilities loans 23 (1,061 ) (43 ) (1,044 ) (18 ) (1,024 ) (25 ) Trade and other receivables 16 16 n/a 15 n/a 25 n/a Trade and other payables 17 (1 ) n/a – n/a – n/a Current asset investments 21 61 n/a 34 n/a 28 n/a Current liabilities loans 23 (1,040 ) n/a (18 ) n/a (159 ) n/a a During the year we made cash payments of £ 1,514 m to BT Group plc offset by the receipt of £ 6 m from BT Group plc resulting in net cash outflow of £ 1,508 m. In addition there are non cash movements of £41m on non-current asset investments relating to interest on loans, employee share schemes and tax settlements made by BT plc on behalf of BT Group plc

Financial commitments and con_2

Financial commitments and contingent liabilities (Tables)	12 Months Ended
	Mar. 31, 2019
Financial Commitments [Abstract]
Disclosure of Financial Commitments	Financial commitments were as follows: At 31 March 2019 £m 2018 £m Operating lease commitments 6,619 6,597 TV programme rights commitments 2,113 2,823 Capital commitments 1,432 993 Other commitments 253 624 Total 10,417 11,037
Disclosure of Future Minimum Operating Lease Payments	Future minimum operating lease payments were as follows: Payable in the year ending 31 March: 2019 £m 2018 £m 2019 – 600 2020 755 550 2021 641 513 2022 599 486 2023 555 463 2024 512 449 Thereafter 3,557 3,536 Total future minimum operating lease payments 6,619 6,597

Basis of Preparation - Addition

Basis of Preparation - Additional Information (Detail) - GBP (£) £ in Billions	Apr. 01, 2018	Mar. 31, 2018	Mar. 31, 2019
IFRS 15 [Member] | Retained Earnings (Loss) [Member] | Bottom of Range [Member]
Disclosure Of Basis Of Preparation Of Financial Statements [Line Items]
Cumulative increase in retained earnings		£ 1.1
IFRS 15 [Member] | Retained Earnings (Loss) [Member] | Top of Range [Member]
Disclosure Of Basis Of Preparation Of Financial Statements [Line Items]
Cumulative increase in retained earnings		£ 1.5
IFRS 16 [Member] | Bottom of Range [Member]
Disclosure Of Basis Of Preparation Of Financial Statements [Line Items]
Lease liabilities			£ 5.6
IFRS 16 [Member] | Top of Range [Member]
Disclosure Of Basis Of Preparation Of Financial Statements [Line Items]
Lease liabilities			£ 6.6
Before tax [Member] | IFRS 15 [Member] | Retained Earnings (Loss) [Member]
Disclosure Of Basis Of Preparation Of Financial Statements [Line Items]
Cumulative increase in retained earnings	£ 1.3
After tax [Member] | IFRS 15 [Member] | Retained Earnings (Loss) [Member]
Disclosure Of Basis Of Preparation Of Financial Statements [Line Items]
Cumulative increase in retained earnings	£ 1.1

Basis of Preparation - Group In

Basis of Preparation - Group Income Statement (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Basis Of Preparation Of Financial Statements [Line Items]
Revenue	£ 23,428	£ 23,723	£ 24,062
Operating costs	(20,004)	(20,339)	(20,892)
Operating profit (loss)	3,424	3,384	3,170
Profit before tax	2,898	2,804	2,551
Tax	(551)	(620)	(485)
Profit for the year	2,347	£ 2,184	£ 2,066
Adjustments [Member]
Disclosure Of Basis Of Preparation Of Financial Statements [Line Items]
Revenue	(252)
Operating costs	1
Operating profit (loss)	(251)
Profit before tax	(251)
Tax	48
Profit for the year	(203)
Amounts Without Adoption of IFRS 15 (IAS 18) [Member]
Disclosure Of Basis Of Preparation Of Financial Statements [Line Items]
Revenue	23,176
Operating costs	(20,003)
Operating profit (loss)	3,173
Profit before tax	2,647
Tax	(503)
Profit for the year	£ 2,144

Basis of Preparation - Group Ba

Basis of Preparation - Group Balance Sheet (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Apr. 01, 2018	Mar. 31, 2018	Mar. 31, 2017
Non-current assets
Contract assets	£ 249	£ 198
Trade and other receivables	445	431	£ 317	£ 360
Current assets
Contract assets	1,353	1,417
Trade and other receivables	3,238	3,692	4,029	3,860
Current tax receivable	110		77	73
Current liabilities
Trade and other payables	5,827	5,781	7,190	7,476
Contract liabilities	1,225	1,406
Total assets less current liabilities	49,367	47,284	46,137	43,062
Non-current liabilities
Other payables	1,479		1,326	1,298
Contract liabilities	200	87
Equity
Retained earnings	10,191	11,994	10,934	7,163
Total equity and non-current liabilities	49,367	£ 47,284	£ 46,137	£ 43,062
Adjustments [Member]
Non-current assets
Contract assets	(249)
Trade and other receivables	(149)
Current assets
Contract assets	(1,353)
Trade and other receivables	180
Current tax receivable	296
Current liabilities
Trade and other payables	1,313
Contract liabilities	(1,225)
Total assets less current liabilities	(1,363)
Non-current liabilities
Other payables	102
Contract liabilities	(200)
Equity
Retained earnings	(1,265)
Total equity and non-current liabilities	(1,363)
Amounts Without Adoption of IFRS 15 (IAS 18) [Member]
Non-current assets
Trade and other receivables	296
Current assets
Trade and other receivables	3,418
Current tax receivable	406
Current liabilities
Trade and other payables	7,140
Total assets less current liabilities	48,004
Non-current liabilities
Other payables	1,581
Equity
Retained earnings	8,926
Total equity and non-current liabilities	£ 48,004

Prior Year Restatement and Op_3

Prior Year Restatement and Opening Balance Adjustments - Additional Information (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017	Apr. 01, 2018	Mar. 31, 2016
Prior Year Restatement And Opening Balance Adjustments [Line Items]
Total equity	£ 21,788	£ 22,347	£ 18,926	£ 23,407	£ 21,325
Remeasurements of the net pension obligation	(2,102)	1,684	(2,789)
Tax expense on pension re-measurement	£ (384)	263	£ (416)
Increase (Decrease) Due to Corrections of Prior Period Errors [Member]
Prior Year Restatement And Opening Balance Adjustments [Line Items]
Increase in retirement benefit obligation, after tax		393
Increase in retirement benefit obligation, gross		476
Total equity		393
Remeasurements of the net pension obligation		476
Tax expense on pension re-measurement		£ 83

Prior Year Restatement and Op_4

Prior Year Restatement and Opening Balance Adjustments - Group statement of comprehensive income (Details) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Statements [Line Items]
Profit for the year	£ 2,347	£ 2,184	£ 2,066
Items that will not be reclassified to the income statement
Remeasurements of the net pension obligation	(2,102)	1,684	(2,789)
Tax on pension remeasurements	384	(263)	416
Items that have been or may be reclassified to the income statement
Exchange differences on translation of foreign operations	64	(188)	237
Fair value movements on available-for-sale assets		11	(3)
Movements in relation to cash flow hedges:
- net fair value (losses) gains	176	(368)	884
recognised in income and expense	(18)	277	(938)
Tax on components of other comprehensive income that have been or may be reclassified	(41)	1	29
Other comprehensive income (loss) for the year, net of tax	(1,534)	1,154	(2,164)
Total comprehensive income (loss) for the year	£ 813	3,338	£ (98)
Previously reported [Member]
Statements [Line Items]
Profit for the year		2,184
Items that will not be reclassified to the income statement
Remeasurements of the net pension obligation		2,160
Tax on pension remeasurements		(346)
Items that have been or may be reclassified to the income statement
Exchange differences on translation of foreign operations		(188)
Fair value movements on available-for-sale assets		11
Movements in relation to cash flow hedges:
- net fair value (losses) gains		(368)
recognised in income and expense		277
Tax on components of other comprehensive income that have been or may be reclassified		1
Other comprehensive income (loss) for the year, net of tax		1,547
Total comprehensive income (loss) for the year		3,731
Pension restatement [Member]
Items that will not be reclassified to the income statement
Remeasurements of the net pension obligation		(476)
Tax on pension remeasurements		83
Movements in relation to cash flow hedges:
Other comprehensive income (loss) for the year, net of tax		(393)
Total comprehensive income (loss) for the year		£ (393)

Prior Year Restatement and Op_5

Prior Year Restatement and Opening Balance Adjustments - Group balance sheet (Details) - GBP (£) £ in Millions	Mar. 31, 2019	Apr. 01, 2018	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Non-current assets
Intangible assets	£ 14,393	£ 14,455	£ 14,455	£ 15,037
Property, plant and equipment	17,835	17,000	17,000	16,498
Trade and other receivables	445	431	317	360
Contract assets	249	198
Deferred tax assets	1,347	1,326	1,326	1,717
Other non-current assets		14,704	14,704
Non current assets	49,316	48,114	47,802	47,067
Current assets
Trade and other receivables	3,238	3,692	4,029	3,860
Contract assets	1,353	1,417
Cash and cash equivalents	1,664	521	521	526
Other current assets		4,009	4,009
Current assets	10,730	9,639	8,559	7,118
Current liabilities
Loans and other borrowings	3,140	2,298	2,298	2,791
Trade and other payables	5,827	5,781	7,190	7,476
Contract liabilities	1,225	1,406
Current tax liabilities	15	331	83	197
Other current liabilities		653	653
Current liabilities	10,679	10,469	10,224	11,123
Total assets less current liabilities	49,367	47,284	46,137	43,062
Non-current liabilities
Loans and other borrowings	15,837	13,038	13,038	11,105
Contract liabilities	200	87
Retirement benefit obligations	7,182	6,847	6,847	9,088
Other non-current liabilities		3,905	3,905
Non current liabilities	27,579	23,877	23,790	24,136
Equity
Ordinary shares	2,172	2,172	2,172	2,172
All other reserves		9,241	9,241
Retained earnings	10,191	11,994	10,934	7,163
Total shareholders equity	21,788	23,407	22,347	18,926	£ 21,325
Total equity and Liabilities	£ 49,367	£ 47,284	46,137	£ 43,062
IFRS 9 and IFRS 15 Adjustment [Member]
Non-current assets
Trade and other receivables			114
Contract assets			198
Non current assets			312
Current assets
Trade and other receivables			(337)
Contract assets			1,417
Current assets			1,080
Current liabilities
Trade and other payables			(1,409)
Contract liabilities			1,406
Current tax liabilities			248
Current liabilities			245
Total assets less current liabilities			1,147
Non-current liabilities
Contract liabilities			87
Non current liabilities			87
Equity
Retained earnings			1,060
Total shareholders equity			1,060
Total equity and Liabilities			1,147
Previously reported [Member]
Non-current assets
Intangible assets			14,455
Property, plant and equipment			17,000
Trade and other receivables			317
Deferred tax assets			1,243
Other non-current assets			14,704
Non current assets			47,719
Current assets
Trade and other receivables			4,029
Cash and cash equivalents			521
Other current assets			4,009
Current assets			8,559
Current liabilities
Loans and other borrowings			2,298
Trade and other payables			7,190
Current tax liabilities			83
Other current liabilities			653
Current liabilities			10,224
Total assets less current liabilities			46,054
Non-current liabilities
Loans and other borrowings			13,038
Retirement benefit obligations			6,371
Other non-current liabilities			3,905
Non current liabilities			23,314
Equity
Ordinary shares			2,172
All other reserves			9,241
Retained earnings			11,327
Total shareholders equity			22,740
Total equity and Liabilities			46,054
Pension restatement [Member]
Non-current assets
Deferred tax assets			83
Non current assets			83
Current liabilities
Total assets less current liabilities			83
Non-current liabilities
Retirement benefit obligations			476
Non current liabilities			476
Equity
Retained earnings			(393)
Total shareholders equity			(393)
Total equity and Liabilities			£ 83

Segment Information - Summary o

Segment Information - Summary of Results of Reportable Segments (Detail) - GBP (£) £ in Millions		12 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Operating Segments [Line Items]
Revenue		£ 23,428	£ 23,723	£ 24,062
Operating profit (loss)		3,424	3,384	3,170
Net finance expense		(527)	(579)	(610)
Share of post tax profit (loss) of associates and joint ventures		1	(1)	(9)
Profit (loss) before taxation		2,898	2,804	2,551
Before Specific Items [Member]
Disclosure Of Operating Segments [Line Items]
Revenue	[1]	23,459	23,746	24,082
Adjusted EBITDA	[2]	7,395	7,508	7,648
Depreciation and amortisation	[1]	(3,546)	(3,514)	(3,510)
Operating profit (loss)	[1]	3,849	3,994	4,138
Net finance expense		(388)	(361)	(400)
Share of post tax profit (loss) of associates and joint ventures		1	(1)	(9)
Profit (loss) before taxation		3,462	3,632	3,729
Specific Items [Member]
Disclosure Of Operating Segments [Line Items]
Revenue	[3]	(31)	(23)	(20)
Operating profit (loss)	[3]	(425)	(610)	(968)
Net finance expense	[3]	(139)	(218)	(210)
Profit (loss) before taxation	[3]	(564)	(828)	(1,178)
Segment Revenue [Member] | Before Specific Items [Member]
Disclosure Of Operating Segments [Line Items]
Revenue		26,800	27,306	27,738
Internal Revenue [Member] | Before Specific Items [Member]
Disclosure Of Operating Segments [Line Items]
Revenue		(3,341)	(3,560)	(3,656)
Consumer [Member] | Before Specific Items [Member]
Disclosure Of Operating Segments [Line Items]
Revenue	[1]	10,588	10,257	9,924
Adjusted EBITDA	[2]	2,534	2,376	2,168
Depreciation and amortisation	[1]	(1,024)	(992)	(989)
Operating profit (loss)	[1]	1,510	1,384	1,179
Consumer [Member] | Segment Revenue [Member] | Before Specific Items [Member]
Disclosure Of Operating Segments [Line Items]
Revenue		10,695	10,360	10,024
Consumer [Member] | Internal Revenue [Member] | Before Specific Items [Member]
Disclosure Of Operating Segments [Line Items]
Revenue		(107)	(103)	(100)
Enterprise [Member] | Before Specific Items [Member]
Disclosure Of Operating Segments [Line Items]
Revenue	[1]	5,933	6,206	6,495
Adjusted EBITDA	[2]	1,990	2,077	2,261
Depreciation and amortisation	[1]	(634)	(635)	(613)
Operating profit (loss)	[1]	1,356	1,442	1,648
Enterprise [Member] | Segment Revenue [Member] | Before Specific Items [Member]
Disclosure Of Operating Segments [Line Items]
Revenue		6,292	6,647	6,975
Enterprise [Member] | Internal Revenue [Member] | Before Specific Items [Member]
Disclosure Of Operating Segments [Line Items]
Revenue		(359)	(441)	(480)
Global Services [Member] | Before Specific Items [Member]
Disclosure Of Operating Segments [Line Items]
Revenue	[1]	4,735	5,013	5,479
Adjusted EBITDA	[2]	505	434	495
Depreciation and amortisation	[1]	(370)	(424)	(439)
Operating profit (loss)	[1]	135	10	56
Global Services [Member] | Segment Revenue [Member] | Before Specific Items [Member]
Disclosure Of Operating Segments [Line Items]
Revenue		4,735	5,013	5,479
Openreach [Member] | Before Specific Items [Member]
Disclosure Of Operating Segments [Line Items]
Revenue	[1]	2,200	2,262	2,174
Adjusted EBITDA	[2]	2,423	2,615	2,734
Depreciation and amortisation	[1]	(1,468)	(1,401)	(1,414)
Operating profit (loss)	[1]	955	1,214	1,320
Openreach [Member] | Segment Revenue [Member] | Before Specific Items [Member]
Disclosure Of Operating Segments [Line Items]
Revenue		5,075	5,278	5,250
Openreach [Member] | Internal Revenue [Member] | Before Specific Items [Member]
Disclosure Of Operating Segments [Line Items]
Revenue		(2,875)	(3,016)	(3,076)
Other [Member] | Before Specific Items [Member]
Disclosure Of Operating Segments [Line Items]
Revenue	[1]	3	8	10
Adjusted EBITDA	[2]	(57)	6	(10)
Depreciation and amortisation	[1]	(50)	(62)	(55)
Operating profit (loss)	[1]	(107)	(56)	(65)
Other [Member] | Segment Revenue [Member] | Before Specific Items [Member]
Disclosure Of Operating Segments [Line Items]
Revenue		£ 3	£ 8	£ 10
[1]	Before specific items.
[2]	Adjusted EBITDA is defined in the alternative performance measures section on page XX.
[3]	For a definition of specific items, see page [210]. An analysis of specific items is provided in note 10.

Segment Information - Summary_2

Segment Information - Summary of Results of Reportable Segments (Parenthetical) (Detail) - GBP (£) £ in Millions		12 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Operating Segments [Line Items]
Net finance expense		£ 527	£ 579	£ 610
Openreach [Member] | Transfer Of Business From Enterprise To Openreach
Disclosure Of Operating Segments [Line Items]
Revenue			155	152
Adjusted EBITDA			95	101
Operating profit (loss)			54	56
Enterprise [Member]
Disclosure Of Operating Segments [Line Items]
Revenue			224	242
Enterprise [Member] | Transfer Of Business From Enterprise To Openreach
Disclosure Of Operating Segments [Line Items]
Revenue			(117)	(112)
Adjusted EBITDA			(95)	(101)
Operating profit (loss)			(54)	(56)
Specific Items [Member]
Disclosure Of Operating Segments [Line Items]
Net finance expense	[1]	£ 139	£ 218	£ 210
[1]	For a definition of specific items, see page [210]. An analysis of specific items is provided in note 10.

Segment Information - Summary_3

Segment Information - Summary of Internal Revenue and Costs Recorded by Each Reportable Segment (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Internal revenue recorded by
Internal cost	£ 20,004	£ 20,339	£ 20,892
Internal revenue	23,428	23,723	24,062
Internal Revenue and Cost [Member]
Internal revenue recorded by
Internal cost	3,341	3,560	3,656
Internal revenue	3,341	3,560	3,656
Internal Revenue and Cost [Member] | Consumer [Member]
Internal revenue recorded by
Internal cost	983	1,026	1,058
Internal Revenue and Cost [Member] | Enterprise [Member]
Internal revenue recorded by
Internal cost	470	545	598
Internal Revenue and Cost [Member] | Global Services [Member]
Internal revenue recorded by
Internal cost	183	196	249
Internal Revenue and Cost [Member] | Openreach [Member]
Internal revenue recorded by
Internal cost	177	173	165
Internal Revenue and Cost [Member] | Other [Member]
Internal revenue recorded by
Internal cost	1,528	1,620	1,586
Internal Revenue and Cost [Member] | Consumer [Member]
Internal revenue recorded by
Internal revenue	107	103	100
Internal Revenue and Cost [Member] | Consumer [Member] | Enterprise [Member]
Internal revenue recorded by
Internal cost	69	65	62
Internal revenue	69	65	62
Internal Revenue and Cost [Member] | Consumer [Member] | Global Services [Member]
Internal revenue recorded by
Internal cost	20	20	20
Internal revenue	20	20	20
Internal Revenue and Cost [Member] | Consumer [Member] | Other [Member]
Internal revenue recorded by
Internal cost	18	18	18
Internal revenue	18	18	18
Internal Revenue and Cost [Member] | Enterprise [Member]
Internal revenue recorded by
Internal revenue	359	441	480
Internal Revenue and Cost [Member] | Enterprise [Member] | Consumer [Member]
Internal revenue recorded by
Internal cost	63	130	148
Internal revenue	63	130	148
Internal Revenue and Cost [Member] | Enterprise [Member] | Global Services [Member]
Internal revenue recorded by
Internal cost	51	51	71
Internal revenue	51	51	71
Internal Revenue and Cost [Member] | Enterprise [Member] | Openreach [Member]
Internal revenue recorded by
Internal cost	177	173	165
Internal revenue	177	173	165
Internal Revenue and Cost [Member] | Enterprise [Member] | Other [Member]
Internal revenue recorded by
Internal cost	68	87	96
Internal revenue	68	87	96
Internal Revenue and Cost [Member] | Openreach [Member]
Internal revenue recorded by
Internal revenue	2,875	3,016	3,076
Internal Revenue and Cost [Member] | Openreach [Member] | Consumer [Member]
Internal revenue recorded by
Internal cost	920	896	910
Internal revenue	920	896	910
Internal Revenue and Cost [Member] | Openreach [Member] | Enterprise [Member]
Internal revenue recorded by
Internal cost	401	480	536
Internal revenue	401	480	536
Internal Revenue and Cost [Member] | Openreach [Member] | Global Services [Member]
Internal revenue recorded by
Internal cost	112	125	158
Internal revenue	112	125	158
Internal Revenue and Cost [Member] | Openreach [Member] | Other [Member]
Internal revenue recorded by
Internal cost	1,442	1,515	1,472
Internal revenue	£ 1,442	£ 1,515	£ 1,472

Segment Information - Summary_4

Segment Information - Summary of Internal Revenue and Costs Recorded by Each Reportable Segment (Parenthetical) (Detail) - Transfer Of Business From Enterprise To Openreach - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Enterprise [Member]
Disclosure Of Operating Segments [Line Items]
Internal revenue	£ 224	£ 242
Openreach [Member]
Disclosure Of Operating Segments [Line Items]
Internal revenue	£ 38	£ 40

Segment Information - Summary_5

Segment Information - Summary of Capital Expenditure (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Operating Segments [Line Items]
Capital expenditure	£ 3,963	£ 3,522	£ 3,454
Acquisition of spectruma	304
Capital expenditure including spectrum	4,267
Intangible Assets Excluding Goodwill [Member]
Disclosure Of Operating Segments [Line Items]
Capital expenditure	680	642	621
Property, Plant And Equipment [Member]
Disclosure Of Operating Segments [Line Items]
Capital expenditure	3,283	2,880	2,833
Consumer [Member]
Disclosure Of Operating Segments [Line Items]
Capital expenditure	994	919	853
Capital expenditure including spectrum	994
Consumer [Member] | Intangible Assets Excluding Goodwill [Member]
Disclosure Of Operating Segments [Line Items]
Capital expenditure	276	236	225
Consumer [Member] | Property, Plant And Equipment [Member]
Disclosure Of Operating Segments [Line Items]
Capital expenditure	718	683	628
Enterprise [Member]
Disclosure Of Operating Segments [Line Items]
Capital expenditure	501	492	454
Capital expenditure including spectrum	501
Enterprise [Member] | Intangible Assets Excluding Goodwill [Member]
Disclosure Of Operating Segments [Line Items]
Capital expenditure	180	180	141
Enterprise [Member] | Property, Plant And Equipment [Member]
Disclosure Of Operating Segments [Line Items]
Capital expenditure	321	312	313
Global Services [Member]
Disclosure Of Operating Segments [Line Items]
Capital expenditure	245	278	361
Capital expenditure including spectrum	245
Global Services [Member] | Intangible Assets Excluding Goodwill [Member]
Disclosure Of Operating Segments [Line Items]
Capital expenditure	93	92	126
Global Services [Member] | Property, Plant And Equipment [Member]
Disclosure Of Operating Segments [Line Items]
Capital expenditure	152	186	235
Openreach [Member]
Disclosure Of Operating Segments [Line Items]
Capital expenditure	2,081	1,699	1,620
Capital expenditure including spectrum	2,081
Openreach [Member] | Intangible Assets Excluding Goodwill [Member]
Disclosure Of Operating Segments [Line Items]
Capital expenditure	82	70	74
Openreach [Member] | Property, Plant And Equipment [Member]
Disclosure Of Operating Segments [Line Items]
Capital expenditure	1,999	1,629	1,546
Other [Member]
Disclosure Of Operating Segments [Line Items]
Capital expenditure	142	134	166
Acquisition of spectruma	304
Capital expenditure including spectrum	446
Other [Member] | Intangible Assets Excluding Goodwill [Member]
Disclosure Of Operating Segments [Line Items]
Capital expenditure	49	64	55
Other [Member] | Property, Plant And Equipment [Member]
Disclosure Of Operating Segments [Line Items]
Capital expenditure	£ 93	£ 70	£ 111

Segment Information - Summary_6

Segment Information - Summary of Capital Expenditure (Parenthetical) (Detail) - Transfer Of Business From Enterprise To Openreach - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Openreach [Member]
Disclosure Of Operating Segments [Line Items]
Increase (decrease) in property, plant and equipment	£ 41	£ 47
Enterprise [Member]
Disclosure Of Operating Segments [Line Items]
Increase (decrease) in property, plant and equipment	£ (41)	£ (47)

Segment Information - Summary_7

Segment Information - Summary of Geographic Information by Revenue from External Customers and Non-Current Assets (Detail) - GBP (£) £ in Millions		12 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Geographical Areas [Line Items]
Revenue		£ 23,428	£ 23,723	£ 24,062
Before Specific Items [Member]
Disclosure Of Geographical Areas [Line Items]
Revenue	[1]	23,459	23,746	24,082
Non-current assets		32,720	31,810	31,926
UK [Member] | Before Specific Items [Member]
Disclosure Of Geographical Areas [Line Items]
Revenue		19,683	19,687	19,421
Non-current assets		30,057	28,843	28,818
Europe, Middle East and Africa, Excluding the UK [Member] | Before Specific Items [Member]
Disclosure Of Geographical Areas [Line Items]
Revenue		2,280	2,489	2,841
Non-current assets		2,217	2,527	2,535
Americas [Member] | Before Specific Items [Member]
Disclosure Of Geographical Areas [Line Items]
Revenue		936	996	1,148
Non-current assets		336	331	424
Asia Pacific [Member] | Before Specific Items [Member]
Disclosure Of Geographical Areas [Line Items]
Revenue		560	574	672
Non-current assets		£ 110	£ 109	£ 149
[1]	Before specific items.

Revenue - Additional Informatio

Revenue - Additional Information (Detail) - GBP (£) £ in Millions	Apr. 01, 2018	Mar. 31, 2019
Revenue From Contract With Customers [Line Items]
Revenue expected to be recognised in future periods for current contracts		£ 14,296
Contract liabilities	£ 1,216
Impairment losses on contract assets	£ 36
ICT and Managed Networks and Equipment and Other Services [Member]
Revenue From Contract With Customers [Line Items]
Revenue expected to be recognised in future periods for current contracts		£ 9,425
Service contract period		five years
Fixed Access And Mobile Subscription Services [Member]
Revenue From Contract With Customers [Line Items]
Revenue expected to be recognised in future periods for current contracts		£ 4,871
Service contract period		two years

Revenue - Summary of Disaggrega

Revenue - Summary of Disaggregation of Revenue From Contracts With Customers (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Revenue From Contract With Customers [Line Items]
Revenue	£ 23,428	£ 23,723	£ 24,062
Revenue Before Specific Items [Member]
Revenue From Contract With Customers [Line Items]
Revenue		23,746	24,082
Specific Items [Member]
Revenue From Contract With Customers [Line Items]
Revenue		(23)	(20)
ICT and Managed Networks [Member]
Revenue From Contract With Customers [Line Items]
Revenue	4,849
ICT and Managed Networks [Member] | I A S18
Revenue From Contract With Customers [Line Items]
Revenue		5,530	5,927
ICT and Managed Networks [Member] | Enterprise [Member]
Revenue From Contract With Customers [Line Items]
Revenue	2,236
ICT and Managed Networks [Member] | Global Services [Member]
Revenue From Contract With Customers [Line Items]
Revenue	2,613
Fixed Access Subscription Revenue [Member]
Revenue From Contract With Customers [Line Items]
Revenue	9,242
Fixed Access Subscription Revenue [Member] | Consumer [Member]
Revenue From Contract With Customers [Line Items]
Revenue	4,564
Fixed Access Subscription Revenue [Member] | Enterprise [Member]
Revenue From Contract With Customers [Line Items]
Revenue	2,181
Fixed Access Subscription Revenue [Member] | Global Services [Member]
Revenue From Contract With Customers [Line Items]
Revenue	362
Fixed Access Subscription Revenue [Member] | Openreach [Member]
Revenue From Contract With Customers [Line Items]
Revenue	2,135
Mobile Subscription [Member]
Revenue From Contract With Customers [Line Items]
Revenue	5,273
Mobile Subscription [Member] | Consumer [Member]
Revenue From Contract With Customers [Line Items]
Revenue	3,866
Mobile Subscription [Member] | Enterprise [Member]
Revenue From Contract With Customers [Line Items]
Revenue	1,277
Mobile Subscription [Member] | Global Services [Member]
Revenue From Contract With Customers [Line Items]
Revenue	130
Equipment And Other Services [Member]
Revenue From Contract With Customers [Line Items]
Revenue	4,095
Equipment And Other Services [Member] | Consumer [Member]
Revenue From Contract With Customers [Line Items]
Revenue	2,158
Equipment And Other Services [Member] | Enterprise [Member]
Revenue From Contract With Customers [Line Items]
Revenue	239
Equipment And Other Services [Member] | Global Services [Member]
Revenue From Contract With Customers [Line Items]
Revenue	1,630
Equipment And Other Services [Member] | Openreach [Member]
Revenue From Contract With Customers [Line Items]
Revenue	65
Equipment And Other Services [Member] | Other [Member]
Revenue From Contract With Customers [Line Items]
Revenue	3
Broadband And T V | I A S18
Revenue From Contract With Customers [Line Items]
Revenue		4,655	4,477
Mobile | I A S18
Revenue From Contract With Customers [Line Items]
Revenue		6,451	6,358
Calls Lines And Connections | I A S18
Revenue From Contract With Customers [Line Items]
Revenue		5,126	5,069
Transit | I A S18
Revenue From Contract With Customers [Line Items]
Revenue		265	404
Other Products And Services | I A S18
Revenue From Contract With Customers [Line Items]
Revenue		£ 1,719	£ 1,847
Before Specific Items [Member]
Revenue From Contract With Customers [Line Items]
Revenue	23,459
Before Specific Items [Member] | Consumer [Member]
Revenue From Contract With Customers [Line Items]
Revenue	10,588
Before Specific Items [Member] | Enterprise [Member]
Revenue From Contract With Customers [Line Items]
Revenue	5,933
Before Specific Items [Member] | Global Services [Member]
Revenue From Contract With Customers [Line Items]
Revenue	4,735
Before Specific Items [Member] | Openreach [Member]
Revenue From Contract With Customers [Line Items]
Revenue	2,200
Before Specific Items [Member] | Other [Member]
Revenue From Contract With Customers [Line Items]
Revenue	3
Specific Items [Member]
Revenue From Contract With Customers [Line Items]
Revenue	£ (31)

Revenue- Summary of Contract As

Revenue- Summary of Contract Assets and Liabilities Recognised (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Apr. 01, 2018
Contract assets
Contract assets, Current	£ 1,353	£ 1,417
Contract assets, Non-current	249	198
Contract assets	1,602	1,615
Contract liabilities
Contract liabilities, Current	1,225	1,406
Contract liabilities, Non-current	200	87
Contract liabilities	£ 1,425	£ 1,493

Operating Costs - Summary of Op

Operating Costs - Summary of Operating Costs (Detail) - GBP (£) £ in Millions		12 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Operating Costs [Line Items]
Share-based payment expense		£ 67	£ 84	£ 57
Total operating costs		20,004	20,339	20,892
Before Specific Items [Member]
Disclosure Of Operating Costs [Line Items]
Wages and salaries		4,258	4,223	4,128
Social security costs		440	461	477
Other pension costs		611	624	521
Share-based payment expense		67	84	57
Total staff costs		5,376	5,392	5,183
Own work capitalised		(834)	(798)	(813)
Net staff costs		4,542	4,594	4,370
Net indirect labour costs		267	315	399
Net labour costs		4,809	4,909	4,769
Product costs and sales commission		4,464	4,429	4,588
Payments to telecommunications operators		2,059	2,306	2,653
Property and energy costs		1,325	1,285	1,202
Network operating and IT costs		1,026	963	983
TV programme rights charges		841	763	714
Provision and installation		624	657	669
Marketing and sales		322	317	365
Other operating costs		832	831	676
Other operating income		(238)	(222)	(185)
Amortisation of intangible assets		1,154	1,123	1,118
Total operating costs		19,610	19,752	19,944
Operating costs before specific items include the following:
Leaver costs		17	50	86
Research and development expenditure		643	632	638
Operating lease charges		801	732	692
Foreign currency gains		(11)		(12)
Inventories recognised as an expense		2,388	2,588	2,680
Government grants		(3)	(3)	(5)
Before Specific Items [Member] | Owned Property Plant and Equipment [Member]
Disclosure Of Operating Costs [Line Items]
Owned assets		2,390	2,381	2,382
Before Specific Items [Member] | Finance Leased Property Plant and Equipment [Member]
Disclosure Of Operating Costs [Line Items]
Owned assets		2	10	10
Specific Items [Member]
Disclosure Of Operating Costs [Line Items]
Amortisation of intangible assets				62
Total operating costs	[1]	£ 394	£ 587	£ 948
[1]	For a definition of specific items, see page [210]. An analysis of specific items is provided in note 10.

Operating Costs - Summary of _2

Operating Costs - Summary of Operating Costs (Parenthetical) (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Before Specific Items [Member]
Disclosure Of Operating Costs [Line Items]
Net of capitalised indirect labour costs	£ 672	£ 612	£ 463
Amortisation relating to write off of software costs	1,154	1,123	1,118
Research and development expenditure	643	632	638
Before Specific Items [Member] | Amortisation of Internally Developed Software [Member]
Disclosure Of Operating Costs [Line Items]
Research and development expenditure	581	573	577
Before Specific Items [Member] | Operating Costs [Member] | Internally Developed Computer Software and Operating Expenses [Member]
Disclosure Of Operating Costs [Line Items]
Research and development expenditure	62	59	61
Before Specific Items [Member] | Software Development Costs [Member]
Disclosure Of Operating Costs [Line Items]
Capitalised software development costs	472	450	457
Specific Items [Member]
Disclosure Of Operating Costs [Line Items]
Amortisation relating to write off of software costs			62
Leaver costs associated with restructuring and integration	(386)	(241)	0
Specific Items [Member] | Leavers Costs Associated With Restructuring and EE [Member]
Disclosure Of Operating Costs [Line Items]
Leaver costs associated with restructuring and integration	£ 257	£ 168	£ 37

Operating Costs - Summary of Co

Operating Costs - Summary of Compensation of Key Management Personnel (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Operating Costs [Abstract]
Short-term employee benefits	£ 14.9	£ 12.4	£ 10.9
Post employment benefits	1.4	1.4	1.4
Share-based payments	5.2	6.6	5.8
Termination benefits	0.6	2.2
Compensation of key management personnel	£ 22.1	£ 22.6	£ 18.1

Employees - Summary of Number o

Employees - Summary of Number of Employees in the Group (Detail) - Employee	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Number And Average Number Of Employees [Line Items]
Year end	106,700	105,800	106,400
Average	106,500	106,200	105,000
Consumer [Member]
Disclosure Of Number And Average Number Of Employees [Line Items]
Year end	19,700	18,200	17,900
Average	19,000	18,000	16,800
Enterprise [Member]
Disclosure Of Number And Average Number Of Employees [Line Items]
Year end	13,400	13,200	13,400
Average	13,800	13,500	13,200
Global Services [Member]
Disclosure Of Number And Average Number Of Employees [Line Items]
Year end	16,600	16,900	17,500
Average	16,800	17,300	17,400
Openreach [Member]
Disclosure Of Number And Average Number Of Employees [Line Items]
Year end	33,200	31,200	30,900
Average	31,900	31,100	31,600
Other [Member]
Disclosure Of Number And Average Number Of Employees [Line Items]
Year end	23,800	26,300	26,700
Average	25,000	26,300	26,000
UK [Member]
Disclosure Of Number And Average Number Of Employees [Line Items]
Year end	84,300	82,200	82,800
Average	83,400	82,500	82,200
Non-United Kingdom [Member]
Disclosure Of Number And Average Number Of Employees [Line Items]
Year end	22,400	23,600	23,600
Average	23,100	23,700	22,800

Audit, Audit Related and Othe_3

Audit, Audit Related and Other Non-Audit Services - Summary of Fees Paid or Payable to Company's Auditors (Detail) - GBP (£) £ in Thousands	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Auditor Remuneration [Line Items]
Audit services fees	£ 14,167	£ 11,238	£ 9,935
Other non-audit services	958	803	3,009
Total services	17,361	13,672	14,809
British Telecommunications plc [Member]
Auditor Remuneration [Line Items]
Audit services fees	8,118	5,372	4,271
Subsidiaries [Member]
Auditor Remuneration [Line Items]
Audit services fees	6,049	5,866	5,664
Audit Related Assurance Services
Auditor Remuneration [Line Items]
Other non-audit services	2,236	1,631	1,865
Tax Compliance Services
Auditor Remuneration [Line Items]
Other non-audit services			366
Tax Advisory Services
Auditor Remuneration [Line Items]
Other non-audit services			111
Other Assurance Services
Auditor Remuneration [Line Items]
Other non-audit services	748	211	200
All Other Non Audit Services
Auditor Remuneration [Line Items]
Other non-audit services	£ 210	£ 592	£ 2,332

Audit, Audit Related and Othe_4

Audit, Audit Related and Other Non-Audit Services - Additional Information (Detail) - GBP (£) £ in Thousands	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Transactions Between Related Parties [Line Items]
Audit services fees	£ 14,167	£ 11,238	£ 9,935
Excludes Amounts for Audit of BT Group Employee Share Ownership Trust and Ilford Trustees (Jersey) Limited [Member]
Disclosure Of Transactions Between Related Parties [Line Items]
Audit services fees	32,000,000
PricewaterhouseCoopersLLP [Member]
Disclosure Of Transactions Between Related Parties [Line Items]
Audit services fees	446,000,000
PricewaterhouseCoopersLLP [Member] | BT Pension Scheme [Member]
Disclosure Of Transactions Between Related Parties [Line Items]
Total fees paid to auditors		£ 2,100	£ 2,100
KPMG LLP [Member] | BT Pension Scheme [Member]
Disclosure Of Transactions Between Related Parties [Line Items]
Total fees paid to auditors	£ 1,100

Audit, Audit Related and Othe_5

Audit, Audit Related and Other Non-Audit Services - Summary of Total Fees Received by Company's Auditors from the BT Pension Scheme (Detail) - GBP (£) £ in Thousands	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Auditor Remuneration [Line Items]
Audit services fees	£ 14,167	£ 11,238	£ 9,935
Audit related assurance services	958	803	3,009
Total services	17,361	13,672	14,809
Audit Related Assurance Services
Auditor Remuneration [Line Items]
Audit related assurance services	2,236	1,631	1,865
Tax Compliance Services
Auditor Remuneration [Line Items]
Taxation services fees			366
Tax Advisory Services
Auditor Remuneration [Line Items]
Taxation services fees			111
All Other Non Audit Services
Auditor Remuneration [Line Items]
Audit related assurance services	210	592	2,332
BT Pension Scheme [Member]
Auditor Remuneration [Line Items]
Total services	1,120	2,137	2,122
BT Pension Scheme [Member] | Audit Of Financial Statements Of Associates [Member]
Auditor Remuneration [Line Items]
Audit services fees	1,005	345	251
BT Pension Scheme [Member] | Audit Related Assurance Services
Auditor Remuneration [Line Items]
Audit related assurance services	53
BT Pension Scheme [Member] | Tax Compliance Services
Auditor Remuneration [Line Items]
Taxation services fees		153	210
BT Pension Scheme [Member] | Tax Advisory Services
Auditor Remuneration [Line Items]
Taxation services fees		1,074	493
BT Pension Scheme [Member] | All Other Non Audit Services
Auditor Remuneration [Line Items]
Audit related assurance services	£ 62	£ 565	£ 1,168

Specific Items - Summary of Spe

Specific Items - Summary of Specific Items (Detail) - GBP (£) £ in Millions		12 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Revenue
Total revenue		£ (23,428)	£ (23,723)	£ (24,062)
Operating costs
Operating costs		20,004	20,339	20,892
Operating loss		(3,424)	(3,384)	(3,170)
Net finance expense
Total net finance expense		527	579	610
Net specific items charge before tax		(2,898)	(2,804)	(2,551)
Taxation
Total taxation		551	620	485
Net specific items charge after tax		(2,347)	(2,184)	(2,066)
Specific Items [Member]
Revenue
Italian business investigation				22
Retrospective regulatory matters		(31)	(23)	2
Total revenue	[1]	31	23	20
Operating costs
EE acquisition warranty claims			225
Restructuring charges		386	241	0
EE integration costs			46	215
Property rationalisation costs		36	28
Pension equalisation costs		26
Retrospective regulatory matters		(4)	26	481
Italian business investigation		(55)	22	238
Out of period irrecoverable VAT				30
Profit (loss) on disposal of businesses		5	(1)	(16)
Operating costs	[1]	394	587	948
Operating loss	[1]	425	610	968
Net finance expense
Interest expense on retirement benefit obligation		139	218	209
Interest on out of period irrecoverable VAT				1
Total net finance expense	[1]	139	218	210
Net specific items charge before tax	[1]	564	828	1,178
Taxation
Tax credit on specific items above		(112)	(87)	(154)
Tax credit on re-measurement of deferred tax				(63)
Total taxation	[1]	112	87	217
Net specific items charge after tax	[1]	£ 452	£ 741	£ 961
[1]	For a definition of specific items, see page [210]. An analysis of specific items is provided in note 10.

Specific Items - Additional Inf

Specific Items - Additional Information (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Specific Items [Member]
Disclosure Of Specific Items [Line Items]
Restructuring charges	£ 386	£ 241	£ 0
EE integration costs		46	215
Regulatory matters effect	27	49	479
Regulatory matters revenue	31
Regulatory costs recognised as specific items	4
EE acquisition warranty claim		225
Restructuring and Leaver Costs [Member]
Disclosure Of Specific Items [Line Items]
EE integration costs		£ 46	215
Amortisation Charge Relating To Write off of IT Assets
Disclosure Of Specific Items [Line Items]
EE integration costs			£ 62
BT Pension Scheme [Member]
Disclosure Of Specific Items [Line Items]
Restructuring charges	£ 23

Taxation - Additional Informati

Taxation - Additional Information (Detail) - GBP (£)	Apr. 01, 2017	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017	Apr. 01, 2018
Disclosure Of Income Tax Expense [Line Items]
Approximate percentage of provision under tax authority examination		85.00%
Provision for tax uncertainties included in current tax liabilities		£ 252,000,000	£ 240,000,000
Additional amount required for tax settlement		£ 556,000,000
Corporation tax	19.00%	17.00%	17.00%	17.00%
Unused tax losses for which no deferred tax asset recognised		£ 4,200,000,000	£ 4,100,000,000
Undistributed earnings		10,191,000,000	10,934,000,000	£ 7,163,000,000	£ 11,994,000,000
UK [Member]
Disclosure Of Income Tax Expense [Line Items]
Unused tax losses for which no deferred tax asset recognised		16,900,000,000	16,900,000,000
Income tax		18,200,000	23,000,000
Non-United Kingdom [Member]
Disclosure Of Income Tax Expense [Line Items]
Deferred tax liability		0
Undistributed earnings		2,500,000,000	£ 2,400,000,000
European Union [Member]
Disclosure Of Income Tax Expense [Line Items]
Undistributed earnings		970,000,000
Additional income tax		27,500,000
EE [Member]
Disclosure Of Income Tax Expense [Line Items]
Additional amount required for tax settlement		£ 474,000,000

Taxation - Analysis of Our Taxa

Taxation - Analysis of Our Taxation Expenses (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Income Tax Expense [Line Items]
Origination and reversal of temporary differences	£ (20)	£ 46	£ 96
Total current tax expense	(546)	(620)	(670)
Adjustments in respect of earlier years	2	(57)	26
Impact of change in UK corporation tax rate to 17% (2017/18: 17%, 2016/17: 17%)			63
Remeasurement of temporary differences	13	11
Total deferred taxation expense (credit)	(5)		185
Total taxation expense	(551)	(620)	(485)
UK [Member]
Disclosure Of Income Tax Expense [Line Items]
Current	(478)	(614)	(594)
Adjustments in respect of earlier years	(9)	37	33
Non-United Kingdom [Member]
Disclosure Of Income Tax Expense [Line Items]
Current	(74)	(66)	£ (109)
Adjustments in respect of earlier years	£ 15	£ 23

Taxation - Analysis of Our Ta_2

Taxation - Analysis of Our Taxation Expenses (Parenthetical) (Detail)	Apr. 01, 2017	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Income Tax Expense [Line Items]
Change in corporation tax rate	19.00%	17.00%	17.00%	17.00%
UK [Member]
Disclosure Of Income Tax Expense [Line Items]
Corporation tax rate		19.00%	19.00%	20.00%

Taxation - Summary of Factors A

Taxation - Summary of Factors Affecting Our Taxation Expense for the Year (Detail) - GBP (£) £ in Millions		12 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Factors Affecting Our Taxation Expense For The Year [Line Items]
Profit before tax		£ 2,898	£ 2,804	£ 2,551
Expected taxation expense at UK rate of 19% (2017/18: 19%, 2016/17: 20%)		(551)	(533)	(510)
(Higher) lower taxes on non-UK profits		(7)	(8)	(29)
Net permanent differences between tax and accounting		(35)	(100)	(183)
Adjustments in respect of earlier years		8	3	59
Prior year non-UK losses used against current year profits		21	16	120
Non-UK losses not recognised			(9)	(8)
Lower taxes on profit on disposal of business				3
Re-measurement of deferred tax balances		13	11	63
Total taxation expense		(551)	(620)	(485)
Specific Items [Member]
Disclosure Of Factors Affecting Our Taxation Expense For The Year [Line Items]
Profit before tax	[1]	(564)	(828)	(1,178)
Total taxation expense	[1]	(112)	(87)	(217)
Before Specific Items [Member]
Disclosure Of Factors Affecting Our Taxation Expense For The Year [Line Items]
Profit before tax		3,462	3,632	3,729
Total taxation expense		£ (663)	£ (707)	£ (702)
[1]	For a definition of specific items, see page [210]. An analysis of specific items is provided in note 10.

Taxation - Summary of Factors_2

Taxation - Summary of Factors Affecting Our Taxation Expense for the Year (Parenthetical) (Detail)	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Factors Affecting Our Taxation Expense For The Year [Abstract]
Tax rate	19.00%	19.00%	20.00%

Taxation - Summary of Tax Compo

Taxation - Summary of Tax Components of Other Comprehensive Income (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Income Tax Relating To Components Of Other Comprehensive Income [Abstract]
Tax on pension remeasurements	£ 384	£ (263)	£ 416
Exchange differences on translation of foreign operations	(4)	(9)	21
Fair value movements on cash flow hedges - net fair value gains or losses	(37)	57	(131)
Fair value movements on cash flow hedges - recognised in income and expense		(47)	139
Income tax relating to components of other comprehensive income	343	(262)	445
Current tax credit	395	203	122
Deferred tax (expense) credit	£ (52)	£ (465)	£ 323

Taxation - Summary of Tax Com_2

Taxation - Summary of Tax Components of Other Comprehensive Income (Parenthetical) (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Income Tax Relating To Components Of Other Comprehensive Income [Abstract]
Current tax credit includes cash contributions made to reduce retirement benefit obligations	£ 391	£ 212	£ 110

Taxation - Summary of Tax (Expe

Taxation - Summary of Tax (Expense) Credit Recognised Directly in Equity (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Tax Expense Credit Recognised Directly In Equity [Abstract]
Tax (expense) credit relating to share-based payments	£ (2)	£ (6)

Taxation - Summary of Deferred

Taxation - Summary of Deferred Taxation (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Apr. 01, 2018	Mar. 31, 2017
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning balance	£ 14	£ (477)
Expense (credit) recognised in the income statement	(5)
Expense (credit) recognised in other comprehensive income (restated)	52	465
Expense (credit) recognised in equity	(1)	6
Exchange differences		3
Transfer to current tax		17
Ending balance	60	14
Deferred tax asset	(1,347)	(1,326)	£ (1,326)	£ (1,717)
Deferred tax liability	1,407	1,340		£ 1,240
Fixed Asset Temporary Differences [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning balance	1,460	1,432
Expense (credit) recognised in the income statement	(60)	11
Expense (credit) recognised in other comprehensive income (restated)		0
Transfer to current tax		17
Ending balance	1,400	1,460
Deferred tax asset	(27)	(41)
Deferred tax liability	1,427	1,501
Retirement Benefit Obligations [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning balance	(1,166)	(1,537)
Expense (credit) recognised in the income statement	(59)	(104)
Expense (credit) recognised in other comprehensive income (restated)	15	475
Ending balance	(1,210)	(1,166)
Deferred tax asset	(1,210)	(1,166)
Share-Based Payments [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning balance	(7)	(17)
Expense (credit) recognised in the income statement	1	4
Expense (credit) recognised in equity	(1)	6
Exchange differences	1
Ending balance	(6)	(7)
Deferred tax asset	(6)	(7)
Tax Losses [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning balance	(183)	(270)
Expense (credit) recognised in the income statement	114	89
Expense (credit) recognised in other comprehensive income (restated)		0
Exchange differences	(1)	(2)
Ending balance	(70)	(183)
Deferred tax asset	(70)	(183)
Other [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Beginning balance	(90)	(85)
Expense (credit) recognised in the income statement	(1)	0
Expense (credit) recognised in other comprehensive income (restated)	37	(10)
Exchange differences		5
Ending balance	(54)	(90)
Deferred tax asset	(54)	(90)
Jurisdictional Offset [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Deferred tax asset	20	161
Deferred tax liability	£ (20)	£ (161)

Taxation - Summary of Deferre_2

Taxation - Summary of Deferred Taxation (Parenthetical) (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Total deferred tax	£ (60)	£ (14)	£ 477
Defined Contribution Plan [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Total deferred tax	£ 2	£ 2

Taxation - Summary of Restricte

Taxation - Summary of Restricted Loss (Detail) £ in Millions	12 Months Ended
	Mar. 31, 2019GBP (£)
Disclosure Of Unrecognised Tax Losses And Other Temporary Differences [Line Items]
Total restricted losses	£ 224
Unrestricted operating losses	3,905
Other temporary differences	108
Total	4,237
Europe [Member]
Disclosure Of Unrecognised Tax Losses And Other Temporary Differences [Line Items]
Total restricted losses	£ 16
Europe [Member] | Bottom of Range [Member]
Disclosure Of Unrecognised Tax Losses And Other Temporary Differences [Line Items]
Deferred tax assets restricted losses expiry date	2019
Europe [Member] | Top of Range [Member]
Disclosure Of Unrecognised Tax Losses And Other Temporary Differences [Line Items]
Deferred tax assets restricted losses expiry date	2038
Americas [Member]
Disclosure Of Unrecognised Tax Losses And Other Temporary Differences [Line Items]
Total restricted losses	£ 205
Americas [Member] | Bottom of Range [Member]
Disclosure Of Unrecognised Tax Losses And Other Temporary Differences [Line Items]
Deferred tax assets restricted losses expiry date	2019
Americas [Member] | Top of Range [Member]
Disclosure Of Unrecognised Tax Losses And Other Temporary Differences [Line Items]
Deferred tax assets restricted losses expiry date	2038
Other Countries [Member]
Disclosure Of Unrecognised Tax Losses And Other Temporary Differences [Line Items]
Total restricted losses	£ 3
Other Countries [Member] | Bottom of Range [Member]
Disclosure Of Unrecognised Tax Losses And Other Temporary Differences [Line Items]
Deferred tax assets restricted losses expiry date	2019
Other Countries [Member] | Top of Range [Member]
Disclosure Of Unrecognised Tax Losses And Other Temporary Differences [Line Items]
Deferred tax assets restricted losses expiry date	2038

Dividends - Additional Informat

Dividends - Additional Information (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2017	May 24, 2019	Mar. 31, 2018
Disclosure Of Dividends Paid And Proposed [Line Items]
Dividends paid	£ 2,500	£ 2,350
BT Group Investments Limited [Member]
Disclosure Of Dividends Paid And Proposed [Line Items]
Dividends paid	2,500	£ 2,350
Final dividend declared				£ 2,500
BT Group Investments Limited [Member] | Events After Reporting Period [Member]
Disclosure Of Dividends Paid And Proposed [Line Items]
Final dividend declared	£ 1,575		£ 1,575

Intangible Assets - Additional

Intangible Assets - Additional Information (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disclosure of information for cash-generating units [Line Items]
Initial licence period	20 years
Pre-tax discount rate	8.20%	8.40%
Global Services [Member]
Disclosure of information for cash-generating units [Line Items]
Pre-tax discount rate	8.70%	8.80%
Perpetuity growth rate	2.40%	2.30%
Amount by which unit's recoverable amount exceeds its carrying amount	£ 1,190	£ 768
Sensitivity analysis, percentage to increase in discount rate	13.50%
Sensitivity analysis of reduction in perpetuity growth rate revised assumption	4.00%
Sensitivity analysis, decrease in cash flows projection	42.00%
Enterprise [Member]
Disclosure of information for cash-generating units [Line Items]
Perpetuity growth rate	2.00%	2.00%
Consumer [Member]
Disclosure of information for cash-generating units [Line Items]
Perpetuity growth rate	2.00%	2.00%
EECGU [Member]
Disclosure of information for cash-generating units [Line Items]
Perpetuity growth rate	2.00%	2.00%

Intangible Assets - Summary of

Intangible Assets - Summary of Estimated Useful Economic Lives Assigned to Principal Categories of Intangible Assets (Detail)	12 Months Ended
	Mar. 31, 2019
Computer Software [Member}
Disclosure Of Intangible Assets [Line Items]
Estimated useful economic lives	2 to 10 years
Telecommunications Licences [Member]
Disclosure Of Intangible Assets [Line Items]
Estimated useful economic lives	2 to 20 years
Customer Relationships and Brands [Member]
Disclosure Of Intangible Assets [Line Items]
Estimated useful economic lives	1 to 15 years

Intangible Assets - Summary o_2

Intangible Assets - Summary of Intangible Assets (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]
Beginning balance	£ 14,455	£ 15,037
Ending balance	14,393	14,455
Gross Carrying Amount [Member]
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]
Beginning balance	20,710	20,625
Additions	984	642
Acquisitions		17
Disposals and adjustments	(1,091)	(474)
Transfers	44
Exchange differences	59	(100)
Ending balance	20,706	20,710
Accumulated Depreciation and Amortisation [Member]
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]
Beginning balance	6,255	5,588
Charge for the year	1,154	1,123
Disposals and adjustments	(1,091)	(465)
Transfers	3
Exchange differences	(8)	9
Ending balance	6,313	6,255
Goodwill [Member]
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]
Beginning balance	7,953
Ending balance	8,014	7,953
Goodwill [Member] | Gross Carrying Amount [Member]
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]
Beginning balance	7,953	8,042
Acquisitions		14
Disposals and adjustments	(2)	(3)
Exchange differences	63	(100)
Ending balance	8,014	7,953
Customer Relationships and Brands [Member]
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]
Beginning balance	2,219
Ending balance	1,846	2,219
Customer Relationships and Brands [Member] | Gross Carrying Amount [Member]
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]
Beginning balance	3,410	3,422
Exchange differences	7	(12)
Ending balance	3,417	3,410
Customer Relationships and Brands [Member] | Accumulated Depreciation and Amortisation [Member]
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]
Beginning balance	1,191	813
Charge for the year	377	379
Exchange differences	3	(1)
Ending balance	1,571	1,191
Telecoms Licences and Other [Member]
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]
Beginning balance	2,530
Ending balance	2,692	2,530
Telecoms Licences and Other [Member] | Gross Carrying Amount [Member]
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]
Beginning balance	2,951	2,945
Additions	304
Acquisitions		3
Disposals and adjustments	(3)	(3)
Transfers	4
Exchange differences	(4)	6
Ending balance	3,252	2,951
Telecoms Licences and Other [Member] | Accumulated Depreciation and Amortisation [Member]
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]
Beginning balance	421	280
Charge for the year	142	141
Disposals and adjustments	(3)	(3)
Transfers	3
Exchange differences	(3)	3
Ending balance	560	421
Internally Developed Software [Member]
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]
Beginning balance	1,142
Ending balance	1,297	1,142
Internally Developed Software [Member] | Gross Carrying Amount [Member]
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]
Beginning balance	4,822	4,363
Additions	520	517
Disposals and adjustments	(945)	(55)
Transfers	120
Exchange differences	1	(3)
Ending balance	4,518	4,822
Internally Developed Software [Member] | Accumulated Depreciation and Amortisation [Member]
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]
Beginning balance	3,680	3,193
Charge for the year	525	525
Disposals and adjustments	(941)	(36)
Transfers	(43)
Exchange differences		(2)
Ending balance	3,221	3,680
Purchased Software [Member]
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]
Beginning balance	611
Ending balance	544	611
Purchased Software [Member] | Gross Carrying Amount [Member]
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]
Beginning balance	1,574	1,853
Additions	160	125
Disposals and adjustments	(141)	(413)
Transfers	(80)
Exchange differences	(8)	9
Ending balance	1,505	1,574
Purchased Software [Member] | Accumulated Depreciation and Amortisation [Member]
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]
Beginning balance	963	1,302
Charge for the year	110	78
Disposals and adjustments	(147)	(426)
Transfers	43
Exchange differences	(8)	9
Ending balance	£ 961	£ 963

Intangible Assets - Summary o_3

Intangible Assets - Summary of Intangible Assets (Parenthetical) (Detail) - GBP (£) £ in Billions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Abstract]
Amortisation charge related to write off of assets	£ 1	£ 0.4

Intangible Assets - Summary o_4

Intangible Assets - Summary of Goodwill Allocated to Cash Generating Units (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disclosure Of Goodwill Allocated To C G Us [Line Items]
Beginning balance	£ 7,953	£ 8,042
Exchange differences	63	(100)
Acquisitions and disposals	(2)	11
Ending balance	8,014	7,953
Legacy BT Consumer [Member]
Disclosure Of Goodwill Allocated To C G Us [Line Items]
Beginning balance	1,183	1,183
Ending balance	1,183	1,183
Legacy EE [Member]
Disclosure Of Goodwill Allocated To C G Us [Line Items]
Beginning balance	2,768	2,768
Ending balance	2,768	2,768
Enterprise [Member]
Disclosure Of Goodwill Allocated To C G Us [Line Items]
Transfers	3,504
Exchange differences	5
Ending balance	3,509
Business and Public Sectors [Member]
Disclosure Of Goodwill Allocated To C G Us [Line Items]
Beginning balance	2,562	2,570
Transfers	(2,562)
Exchange differences		(8)
Ending balance		2,562
Global Services [Member]
Disclosure Of Goodwill Allocated To C G Us [Line Items]
Beginning balance	498	579
Exchange differences	58	(92)
Acquisitions and disposals	(2)	11
Ending balance	554	498
Wholesale And Ventures [Member]
Disclosure Of Goodwill Allocated To C G Us [Line Items]
Beginning balance	942	942
Transfers	£ (942)
Ending balance		£ 942

Property, Plant and Equipment -

Property, Plant and Equipment - Summary of Estimated Useful Lives Assigned to Principal Categories of Assets (Detail)	12 Months Ended
	Mar. 31, 2019
Freehold Buildings [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful lives of property, plant and equipment	14 to 50 years
Short-Term Leasehold Improvements [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful lives of property, plant and equipment	Shorter of 10 years or lease term
Leasehold Land and Buildings [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful lives of property, plant and equipment	Unexpired portion of lease or 40 years, whichever is the shorter
Network Infrastructure [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful lives of property, plant and equipment	more than 18 years
Network Infrastructure [Member] | Duct [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful lives of property, plant and equipment	40 years
Network Infrastructure [Member] | Cable [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful lives of property, plant and equipment	3 to 25 years
Network Infrastructure [Member] | Fibre Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful lives of property, plant and equipment	5 to 20 years
Network Infrastructure [Member] | Exchange Equipment [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful lives of property, plant and equipment	2 to 13 years
Network Infrastructure [Member] | Other Network Equipment [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful lives of property, plant and equipment	2 to 20 years
Motor Vehicles [Member] | Other Assets [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful lives of property, plant and equipment	2 to 9 years
Computer Equipment [Member] | Other Assets [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful lives of property, plant and equipment	3 to 7 years

Property, Plant and Equipment_2

Property, Plant and Equipment - Summary of the Carrying Values of Software, Property, Plant and Equipment (Detail) - GBP (£) £ in Millions		12 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Disclosure of detailed information about property, plant and equipment [Line Items]
Opening balance		£ 17,000	£ 16,498
Ending balance		17,835	17,000
Ending balance		17,770	16,956
Engineering Stores [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Engineering stores		65	44
Gross Carrying Amount [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Opening balance		55,077	54,025
Additions	[1]	3,262	2,894
Transfers		(44)
Disposals and adjustments	[2]	(2,352)	(1,789)
Exchange differences		(30)	(53)
Ending balance		55,913	55,077
Accumulated Depreciation and Amortisation [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Opening balance		38,121	37,585
Depreciation of property, plant and equipment		2,392	2,391
Transfers		(3)
Disposals and adjustments	[2]	(2,340)	(1,816)
Exchange differences		(27)	(39)
Ending balance		38,143	38,121
Land and Buildings [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Opening balance	[3]	489
Ending balance	[3]	387	489
Ending balance	[3]	387	489
Land and Buildings [Member] | Gross Carrying Amount [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Opening balance	[3]	1,262	1,302
Additions	[1],[3]	12	12
Transfers	[3]	13	36
Disposals and adjustments	[2],[3]	(178)	(82)
Exchange differences	[3]	(2)	(6)
Ending balance	[3]	1,107	1,262
Land and Buildings [Member] | Accumulated Depreciation and Amortisation [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Opening balance	[3]	773	817
Depreciation of property, plant and equipment	[3]	51	57
Transfers	[3]	1
Disposals and adjustments	[2],[3]	(104)	(96)
Exchange differences	[3]	(1)	(5)
Ending balance	[3]	720	773
Network Infrastructure [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Opening balance	[3]	14,993
Ending balance	[3]	15,841	14,993
Ending balance	[3]	15,841	14,993
Network Infrastructure [Member] | Gross Carrying Amount [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Opening balance	[3]	50,783	49,372
Additions	[1],[3]	97	193
Transfers	[3]	2,988	2,793
Disposals and adjustments	[2],[3]	(1,943)	(1,540)
Exchange differences	[3]	(32)	(35)
Ending balance	[3]	51,893	50,783
Network Infrastructure [Member] | Accumulated Depreciation and Amortisation [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Opening balance	[3]	35,790	35,214
Depreciation of property, plant and equipment	[3]	2,236	2,213
Transfers	[3]	(4)
Disposals and adjustments	[2],[3]	(1,940)	(1,613)
Exchange differences	[3]	(30)	(24)
Ending balance	[3]	36,052	35,790
Other [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Opening balance	[4]	356
Ending balance	[4]	351	356
Ending balance	[4]	351	356
Other [Member] | Gross Carrying Amount [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Opening balance	[4]	1,914	1,938
Additions	[1],[4]	119	92
Transfers	[4]	18	16
Disposals and adjustments	[2],[4]	(333)	(119)
Exchange differences	[4]	4	(13)
Ending balance	[4]	1,722	1,914
Other [Member] | Accumulated Depreciation and Amortisation [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Opening balance	[4]	1,558	1,554
Depreciation of property, plant and equipment	[4]	105	121
Disposals and adjustments	[2],[4]	(296)	(107)
Exchange differences	[4]	4	(10)
Ending balance	[4]	1,371	1,558
Assets in Course of Construction [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Opening balance		1,162
Ending balance		1,256	1,162
Ending balance		1,191	1,118
Assets in Course of Construction [Member] | Engineering Stores [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Engineering stores		65	44
Assets in Course of Construction [Member] | Gross Carrying Amount [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Opening balance		1,118	1,413
Additions	[1]	3,034	2,597
Transfers		(3,063)	(2,845)
Disposals and adjustments	[2]	102	(48)
Exchange differences			1
Ending balance		£ 1,191	£ 1,118
[1]	Net of grant deferral of £63m (2017/18: £74m net grant funding).
[2]	Fully depreciated assets in the group’s fixed asset registers were reviewed during the year, as part of the group’s annual asset verification exercise, and certain assets that were no longer in use have been written off, reducing cost and accumulated depreciation by £1.9bn (2017/18: £1.3bn).
[3]	The carrying amount of the group’s property, plant and equipment includes an amount of £34m (2017/18: £53m) in respect of assets held under finance leases, comprising land and buildings of £34m (2017/18: £42m) and network infrastructure of £nil (2017/18: £11m). The depreciation expense on those assets in 2018/19 was £2m (2017/18: £10m), comprising land and buildings of £2m (2017/18: £3m) and network infrastructure of £nil (2017/18: £7m).
[4]	Other mainly comprises motor vehicles, computers and fixtures and fittings.

Property, Plant and Equipment_3

Property, Plant and Equipment - Summary of the Carrying Values of Software, Property, Plant and Equipment (Parenthetical) (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disclosure of detailed information about property, plant and equipment [Line Items]
Carrying amount of assets held under finance leases	£ 34	£ 53
Depreciation on assets held under finance leases	2	10
Net grant deferral	63
Net grant funding		74
Write off of fully depreciated assets	1,900	1,300
Disposals and adjustments, assets held for sale	89
Change in discounting assumptions of lease-end obligations	124
Land and Buildings [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Carrying amount of assets held under finance leases	34	42
Depreciation on assets held under finance leases	£ 2	3
Network Infrastructure [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Carrying amount of assets held under finance leases		11
Depreciation on assets held under finance leases		£ 7

Property, Plant and Equipment_4

Property, Plant and Equipment - Summary of Property, Plant and Equipment (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Mar. 31, 2018
Disclosure of detailed information about property, plant and equipment [Line Items]
Total land and buildings	£ 387	£ 489
Freehold [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Total land and buildings	158	261
Leasehold [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Total land and buildings	£ 229	£ 228

Property, Plant and Equipment_5

Property, Plant and Equipment - Additional Information (Detail) - Network Infrastructure [Member] - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disclosure of detailed information about property, plant and equipment [Line Items]
Net book value of share of assets owned by joint ventures	£ 584	£ 526
Value of share of assets owned	125	132
Net book value of assets	£ 9,000	£ 8,300
Useful life of assets	more than 18 years

Programme Rights - Summary of P

Programme Rights - Summary of Programme Rights (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disclosure Of Intangible Assets [Line Items]
Beginning balance	£ 272	£ 264
Ending balance	310	272
Programme Rights [Member]
Disclosure Of Intangible Assets [Line Items]
Beginning balance	272	264
Additions	879	771
Amortisation	(841)	(763)
Ending balance	£ 310	£ 272

Trade and Other Receivables - S

Trade and Other Receivables - Schedule of Trade and Other Receivables (Detail) - GBP (£) £ in Millions		Mar. 31, 2019	Apr. 01, 2018	Mar. 31, 2018	Mar. 31, 2017
Current
Trade receivables		£ 1,732		£ 1,741	£ 1,774
Amounts owed by ultimate parent company		16		15	25
Prepayments	[1]	698		1,103	733
Accrued income	[2]	34		777	955
Deferred contract costs	[3]	417
Other receivables	[4]	341		393	373
Trade and other receivable current		3,238	£ 3,692	4,029	3,860
Non-current
Other assets	[5]	173		317	360
Deferred contract costs	[3]	272
Trade and other non-current receivables		£ 445	£ 431	£ 317	£ 360
[1]	2017/18 includes £325m in respect of the acquisition of Spectrum.
[2]	Accrued income recognised in prior years has been substantially reclassified to contract assets on adoption of IFRS 15. See notes 1 and 2.
[3]	Deferred contract costs arise following adoption of IFRS 15 on 1 April 2018. See notes 1 and 2.
[4]	Other receivables includes assets held for sale of £nil. (2017/18: £nil, 2016/17: £22m). £89m assets held for sale as at 31 March 2019 are presented separately on the face of the balance sheet.
[5]	Other assets comprise prepayments and leasing debtors. Included in prior year comparatives are costs relating to the initial set-up, transition or transformation phase of long-term networked IT services contracts (2017/18: £145m, 2016/17: £163m), which are presented within deferred contract costs following adoption of IFRS 15.

Trade and Other Receivables -_2

Trade and Other Receivables - Schedule of Trade and Other Receivables (Parenthetical) (Detail) - GBP (£) £ in Millions		Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Trade And Other Receivables [Line Items]
Other receivables	[1]	£ 341	£ 393	£ 373
Assets held for sale		89
Other assets relating to initial set-up, transition or transformation phase of long-term networked IT services contracts	[2]	173	317	360
Spectrum [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Prepayments in respect of acquisition		0	325	0
Current Assets Held for Sale [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Other receivables		0	0	22
Assets held for sale		£ 89
Deferred Contract Costs [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Other assets relating to initial set-up, transition or transformation phase of long-term networked IT services contracts			£ 145	£ 163
[1]	Other receivables includes assets held for sale of £nil. (2017/18: £nil, 2016/17: £22m). £89m assets held for sale as at 31 March 2019 are presented separately on the face of the balance sheet.
[2]	Other assets comprise prepayments and leasing debtors. Included in prior year comparatives are costs relating to the initial set-up, transition or transformation phase of long-term networked IT services contracts (2017/18: £145m, 2016/17: £163m), which are presented within deferred contract costs following adoption of IFRS 15.

Trade and Other Receivables -_3

Trade and Other Receivables - Summary of Trade Receivables After Deducting Allowances for Doubtful Debts (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Trade And Other Receivables [Abstract]
At 1 April	£ 375	£ 303	£ 195
Expense	95	129	211
Utilised	(165)	(61)	(114)
Exchange differences	(6)	4	11
At 31 March	£ 299	£ 375	£ 303

Trade and Other Receivables -_4

Trade and Other Receivables - Summary of Trade Receivables Past Due and Not Specifically Impaired (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Trade And Other Receivables [Line Items]
Trade receivables	£ 1,732	£ 1,741	£ 1,774
Trade receivables specifically impaired net of provision	34	61	146
Current [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Trade receivables	1,229	1,251	1,184
Between 0 and 3 Months [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Trade receivables	371	293	292
Between 3 and 6 Months [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Trade receivables	42	44	17
Between 6 and 12 Months [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Trade receivables	40	25	41
Over 12 Months [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Trade receivables	£ 16	£ 67	£ 94

Trade and Other Receivables - A

Trade and Other Receivables - Additional Information (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Disclosure Of Trade And Other Receivables [Line Items]
Cash collateral held against trade and other receivables		£ 9	£ 6	£ 4
Gross Trade Receivables Specifically Impaired [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Gross trade receivables specifically impaired	£ 57	£ 124	£ 238

Trade and Other Receivables -_5

Trade and Other Receivables - Schedule of Trade Receivables Not Past Due and Accrued Income (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Trade And Other Receivables [Line Items]
Accrued income	£ 34	£ 777	£ 955
Current [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Trade receivables not past due	1,229	1,251	1,184
Consumer Segment [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Accrued income	32
Consumer Segment [Member] | Current [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Trade receivables not past due	457
Enterprise Segment [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Accrued income	2
Enterprise Segment [Member] | Current [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Trade receivables not past due	274
Global Services [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Accrued income		222	297
Global Services [Member] | Current [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Trade receivables not past due	£ 498	477	444
Consumer [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Accrued income		86	90
Consumer [Member] | Current [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Trade receivables not past due		157	128
Openreach [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Accrued income		67	78
Openreach [Member] | Current [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Trade receivables not past due		61	1
E E
Disclosure Of Trade And Other Receivables [Line Items]
Accrued income		122	170
E E | Current [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Trade receivables not past due		206	335
Business and Public Sectors [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Accrued income		134	151
Business and Public Sectors [Member] | Current [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Trade receivables not past due		253	200
Other [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Accrued income		1	2
Other [Member] | Current [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Trade receivables not past due		5	1
Wholesale And Ventures [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Accrued income		145	167
Wholesale And Ventures [Member] | Current [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Trade receivables not past due		£ 92	£ 75

Trade and Other Receivables -_6

Trade and Other Receivables - Summary of Movement on Deferred Costs (Detail) £ in Millions	12 Months Ended
	Mar. 31, 2019GBP (£)
Disclosure Of Trade And Other Receivables [Line Items]
Beginning balance	£ 669
Additions	569
Amortisation	(569)
Impairment	(10)
Other	30
Ending balance	689
Deferred Connection Costs [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Beginning balance	7
Additions	15
Amortisation	(14)
Other	23
Ending balance	31
Deferred Contract Acquisition Costs Commissions [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Beginning balance	85
Additions	76
Amortisation	(76)
Impairment	(5)
Other	6
Ending balance	86
Deferred Contract Acquisition Costs Dealer Incentives [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Beginning balance	416
Additions	446
Amortisation	(426)
Impairment	(4)
Ending balance	432
Transition And Transformation [Member]
Disclosure Of Trade And Other Receivables [Line Items]
Beginning balance	161
Additions	32
Amortisation	(53)
Impairment	(1)
Other	1
Ending balance	£ 140

Trade and Other Payables - Summ

Trade and Other Payables - Summary of Trade and Other Payables (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Apr. 01, 2018	Mar. 31, 2018	Mar. 31, 2017
Current
Trade payables	£ 4,141		£ 3,991	£ 4,205
Amounts owed to parent company	55		50	63
Amounts owed to ultimate parent company	1
Other taxation and social security	564		704	704
Other payables	368		428	648
Accrued expenses	630		492	382
Deferred income	68		1,525	1,474
Total current trade and other payables	5,827	£ 5,781	7,190	7,476
Non-current
Other payables	873		871	885
Deferred income	606		455	413
Total non-current trade and other payables	£ 1,479		£ 1,326	£ 1,298

Trade and Other Payables - Su_2

Trade and Other Payables - Summary of Trade and Other Payables (Parenthetical) (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Trade And Other Payables [Line Items]
Deferred income current	£ 68	£ 1,525	£ 1,474
Deferred income non-current	606	455	413
Broadband Delivery UK Programme [Member]
Disclosure Of Trade And Other Payables [Line Items]
Deferred income current	51	132	71
Deferred income non-current	£ 586	£ 404	£ 375

Provisions - Additional Informa

Provisions - Additional Information (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2017	Apr. 01, 2018	Mar. 31, 2018
Disclosure of other provisions [Line Items]
Trade and other payables	£ 5,827	£ 7,476	£ 5,781	£ 7,190
Contract loss provisions	£ 25			£ 38
Fine [Member]
Disclosure of other provisions [Line Items]
Trade and other payables		42
Specific Item [Member] | Regulatory [Member]
Disclosure of other provisions [Line Items]
Additional provisions		£ 300
Top of Range [Member] | Network Share Provision [Member]
Disclosure of other provisions [Line Items]
Number of years for which costs are expected to be incurred	20 years

Provisions - Details of Estimat

Provisions - Details of Estimate of the Provisions (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure of other provisions [Line Items]
Opening balance	£ 1,055	£ 1,161
Additions	315	133
Unwind of discount	14	15	£ 16
Utilised or released	(407)	(336)
Transfers	29	85
Exchange differences		(3)
Ending balance	1,006	1,055	1,161
Restructuring provision [member]
Disclosure of other provisions [Line Items]
Opening balance	12	11
Additions		4
Utilised or released		(2)
Transfers	(12)
Exchange differences		(1)
Ending balance		12	11
Property, plant and equipment [member]
Disclosure of other provisions [Line Items]
Opening balance	294	292
Additions	84	37
Unwind of discount	11	11
Utilised or released	(71)	(46)
Transfers	21
Ending balance	339	294	292
Network ARO Provision [Member]
Disclosure of other provisions [Line Items]
Opening balance	71	83
Additions	102	2
Unwind of discount	2	2
Utilised or released	(13)	(16)
Ending balance	162	71	83
Network Share Provision [Member]
Disclosure of other provisions [Line Items]
Opening balance	33	50
Additions	2
Unwind of discount	1	2
Utilised or released	(9)	(19)
Ending balance	27	33	50
Regulatory [Member]
Disclosure of other provisions [Line Items]
Opening balance	320	479
Additions	58	51
Utilised or released	(196)	(210)
Ending balance	182	320	479
Litigation [Member]
Disclosure of other provisions [Line Items]
Opening balance	64	69
Additions	3	6
Utilised or released	(9)	(11)
Transfers	27
Exchange differences	(1)
Ending balance	84	64	69
Other [Member]
Disclosure of other provisions [Line Items]
Opening balance	261	177
Additions	66	33
Utilised or released	(109)	(32)
Transfers	(7)	85
Exchange differences	1	(2)
Ending balance	£ 212	£ 261	£ 177

Provisions - Details of Provisi

Provisions - Details of Provisions (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Other Provisions [Abstract]
Current	£ 424	£ 603	£ 625
Non-current	582	452	536
Total	£ 1,006	£ 1,055	£ 1,161

Retirement Benefit Plans - Addi

Retirement Benefit Plans - Additional Information (Detail)		Apr. 01, 2009	Jun. 30, 2017GBP (£)	Mar. 31, 2019GBP (£)MemberValuation	Mar. 31, 2018GBP (£)	Jun. 30, 2017GBP (£)	Mar. 31, 2017GBP (£)
Disclosure Of Retirement Benefit Plans [Line Items]
Weighted average term of liabilities				16 years
Length of time over which payments will be made to all retirees from the fund				70 years
Normal pensionable age		60 years
Maximum period of addressing deficit				20 years
Number of recent triennial valuations | Valuation				2
Percentage of investment in growth asset			45.00%			45.00%
De-risking to low risk investment approach year						2034
Flat discount rate			1.00%			1.00%
Threshold dividend per share				10.00%
Threshold dividend per share of share buybacks				£ 200,000,000
Share buybacks in excess per year				200,000,000
Threshold for BTPS				1,500,000,000
Deficit threshold level for application for provision				2,000,000,000
Contribution to plan				£ 2,024,000,000	£ 872,000,000		£ 274,000,000
BTRSS [Member]
Disclosure Of Retirement Benefit Plans [Line Items]
Number of active members | Member				69,000
Contribution to plan					388,000,000
Each Month Between 1 April 2018 and November 2020
Disclosure Of Retirement Benefit Plans [Line Items]
Monthly payments to bridge funding deficit				£ 1,875,000
Group Contribution
Disclosure Of Retirement Benefit Plans [Line Items]
Group contributions based on funding valuation agreement				1,310,000,000
Top of Range [Member]
Disclosure Of Retirement Benefit Plans [Line Items]
Prudent discount rate			1.40%			1.40%
Proceeds from disposals net of acquisitions			£ 1,000,000,000	1,000,000,000
Bottom of Range [Member]
Disclosure Of Retirement Benefit Plans [Line Items]
Prudent discount rate			0.70%			0.70%
Trade and Other Payables [Member]
Disclosure Of Retirement Benefit Plans [Line Items]
Present value of liabilities				£ 42,000,000	£ 17,000,000
BT Pension Scheme [Member]
Disclosure Of Retirement Benefit Plans [Line Items]
Percentage of future benefit accrual				99.00%
Service cost (including administration expenses & PPF levy)				£ 0
Past service credit				£ 0
Number of members in pension scheme | Member				288,000
Number of members in pension plan | Member				50
Percentage of assets of benefit plan	[1]			100.00%	100.00%
BTPS [Member]
Disclosure Of Retirement Benefit Plans [Line Items]
Normal pensionable age		65 years
Percentage of group's retirement benefit obligation				97.00%
Percentage retirement benefit obligation are rounded				0.05%
Percentage of exposure covered by longevity insurance				25.00%
Funding deficit			£ 11,300,000,000			£ 11,300,000,000
Recovery period			13 years
Ordinary Contributions [Member]
Disclosure Of Retirement Benefit Plans [Line Items]
Group contributions based on funding valuation agreement					£ 60,000,000
Deficit Contributions [Member]
Disclosure Of Retirement Benefit Plans [Line Items]
Group contributions based on funding valuation agreement					£ 1,250,000,000
EEPS [Member]
Disclosure Of Retirement Benefit Plans [Line Items]
Funding deficit				£ 141,000,000
Defined benefit liabilities				£ 1,000,000,000
Number of active members | Member				11,000
EE Pension Scheme [Member] | Global Equities [Member]
Disclosure Of Retirement Benefit Plans [Line Items]
Percentage of assets of benefit plan					23.00%
EE Pension Scheme [Member] | Property and Illiquid Alternatives [Member]
Disclosure Of Retirement Benefit Plans [Line Items]
Percentage of assets of benefit plan					22.00%
EE Pension Scheme [Member] | Absolute Return Portfolio [Member]
Disclosure Of Retirement Benefit Plans [Line Items]
Percentage of assets of benefit plan					25.00%
EE Pension Scheme [Member] | Liability Driven Investment Portfolio [Member]
Disclosure Of Retirement Benefit Plans [Line Items]
Percentage of assets of benefit plan					30.00%
[1]	At 31 March 2019, the Scheme did not hold any equity issued by the group (2017/18: £3m). The Scheme also held £2,154m (2017/18: £10m) of bonds issued by the group, reflecting the BTPS fully subscribing to £2bn of bonds issued by BT in June 2018 following agreement of the 2017 funding valuation.

Retirement Benefit Plan - Summa

Retirement Benefit Plan - Summary of Retirement Benefit Plan (Detail)	12 Months Ended
	Mar. 31, 2019
Defined Contribution Plans [Member]
Disclosure of defined benefit plans [Line Items]
What are they?	Benefits in a defined contribution plan are linked to: –contributions paid –the performance of each individual’s chosen investments –the form in which individuals choose to take their benefits. Contributions are paid into an independently administered fund.
How do they impact BT’s financial statements?	The income statement charge in respect of defined contribution plans represents the contribution payable by the group based upon a fixed percentage of employees’ pay. The group has no exposure to investment and other experience risks.
Defined Benefit Plan [Member]
Disclosure of defined benefit plans [Line Items]
What are they?	Benefits in a defined benefit plan are: –determined by the plan rules, dependent on factors such as age, years of service and pensionable pay –not dependent upon actual contributions made by the company or members.
How do they impact BT’s financial statements?	The income statement service cost in respect of defined benefit plans represents the increase in the defined benefit liability arising from pension benefits earned by active members in the current period. The group is exposed to investment and other experience risks and may need to make additional contributions where it is estimated that the benefits will not be met from regular contributions, expected investment income and assets held.

Retirement Benefit Plan - Sum_2

Retirement Benefit Plan - Summary of Expense or Income from Retirement Benefit Arrangements Recognised in Income Statement (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Service Cost [Abstract]
Total recognised in the income statement	£ 799	£ 842	£ 730
Before Specific Items [Member]
Service Cost [Abstract]
Service cost (including administration expenses & PPF levy)	611	624	521
Past service credit		(17)
Specific Items [Member]
Service Cost [Abstract]
– Costs to close BT Pension Scheme and provide transition payments for affected employees	23
– Cost to equalise benefits between men and women due to guaranteed minimum pension (GMP)c	26
– Net interest expense on pensions deficit included in specific items	139	218	209
Service cost (including administration expenses & PPF levy)	188	218	209
Defined Benefit Plan [Member] | Before Specific Items [Member]
Service Cost [Abstract]
Service cost (including administration expenses & PPF levy)	135	376	281
Defined Contribution Plans [Member] | Before Specific Items [Member]
Service Cost [Abstract]
Service cost (including administration expenses & PPF levy)	£ 476	£ 265	£ 240

Retirement Benefit Plan - Sum_3

Retirement Benefit Plan - Summary of Expense or Income from Retirement Benefit Arrangements Recognised in Income Statement (Parenthetical) (Detail) - BT Pension Scheme [Member]	12 Months Ended
	Mar. 31, 2019GBP (£)
Disclosure of defined benefit plans [Line Items]
Service cost (including administration expenses & PPF levy)	£ 0
Past service credit	£ 0

Retirement Benefit Plan - Sum_4

Retirement Benefit Plan - Summary of Pension Obligation in Respect of Defined Benefit Plans Reported in Balance Sheet (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Mar. 31, 2018
Disclosure of defined benefit plans [Line Items]
Deficit	£ (5,974)	£ (5,683)
Retirement Benefit Obligation Before Adjustments [Member]
Disclosure of defined benefit plans [Line Items]
Assets	53,364	50,956
Present value of liabilities	(60,546)	(57,803)
Deficit	(7,182)	(6,847)
Retirement Benefit Obligation Before Adjustments [Member] | BT Pension Scheme [Member]
Disclosure of defined benefit plans [Line Items]
Assets	52,186	49,894
Present value of liabilities	(58,855)	(56,259)
Deficit	(6,669)	(6,365)
Retirement Benefit Obligation Before Adjustments [Member] | EE Pension Scheme [Member]
Disclosure of defined benefit plans [Line Items]
Assets	816	763
Present value of liabilities	(997)	(920)
Deficit	(181)	(157)
Retirement Benefit Obligation Before Adjustments [Member] | Other Pension Plans [Member]
Disclosure of defined benefit plans [Line Items]
Assets	362	299
Present value of liabilities	(694)	(624)
Deficit	(332)	(325)
Deferred Tax Asset [Member]
Disclosure of defined benefit plans [Line Items]
Deficit	£ 1,208	£ 1,164

Retirement Benefit Plan - Sum_5

Retirement Benefit Plan - Summary of Pension Obligation in Respect of Defined Benefit Plans Reported in Balance Sheet (Parenthetical) (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Mar. 31, 2018
Unfunded Pension Arrangements [Member] | Other Plans [Member]
Disclosure of defined benefit plans [Line Items]
Present value of liabilities	£ 101	£ 97

Retirement Benefit Plan - Sum_6

Retirement Benefit Plan - Summary of Movements on Pension Assets and Liabilities (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Assets [Member]
Disclosure of defined benefit plans [Line Items]
Beginning balance	£ 50,956	£ 51,112
Service cost (including administration expenses and PPF levy)	(49)	(67)
Interest on pension deficit	1,356	1,201
Return on plan assets above the amount included in the group income statement	1,607	10
Regular contributions by employer	43	264
Deficit contributions by employer	2,024	872
Contributions by employees	1	2
Benefits paid	(2,564)	(2,449)
Foreign exchange	(4)	11
Ending balance	53,364	50,956
Costs to close BT Pension Scheme	(6)
Liabilities [Member]
Disclosure of defined benefit plans [Line Items]
Beginning balance	(57,803)	(60,200)
Service cost (including administration expenses and PPF levy)	(86)	(309)
Past service credit		17
Interest on pension deficit	(1,495)	(1,419)
Actuarial gain arising from changes in financial assumptionsa	(3,920)	2,251
Actuarial loss arising from changes in demographic assumptionsa (Restated)	247	(697)
Actuarial gain (loss) arising from experience adjustments	(36)	120
Contributions by employees	(1)	(2)
Benefits paid	2,564	2,449
Foreign exchange	10	(13)
Ending balance	(60,546)	(57,803)
Cost to equalise benefits between men and women due to guaranteed minimum pension (GMP)	(26)
Defined Benefit Deficit [Member]
Disclosure of defined benefit plans [Line Items]
Beginning balance	(6,847)	(9,088)
Service cost (including administration expenses and PPF levy)	(135)	(376)
Past service credit		17
Interest on pension deficit	(139)	(218)
Included in the group income statement	(306)	(577)
Return on plan assets above the amount included in the group income statement	1,607	10
Actuarial gain arising from changes in financial assumptionsa	(3,920)	2,251
Actuarial loss arising from changes in demographic assumptionsa (Restated)	247	(697)
Actuarial gain (loss) arising from experience adjustments	(36)	120
Included in the group statement of comprehensive income	(2,102)	1,684
Regular contributions by employer	43	264
Deficit contributions by employer	2,024	872
Included in the group cash flow statement	2,067	1,136
Foreign exchange	6	(2)
Other movements	6	(2)
Ending balance	(7,182)	£ (6,847)
Costs to close BT Pension Scheme	(6)
Cost to equalise benefits between men and women due to guaranteed minimum pension (GMP)	£ (26)

Retirement Benefit Plan - Sum_7

Retirement Benefit Plan - Summary of Analysis of Membership (Detail) - BT Pension Scheme [Member] £ in Billions	Mar. 31, 2019GBP (£)Member
Disclosure of defined benefit plans [Line Items]
IAS 19 liabilities (bn)	£ 58.9
Total number of members | Member	288,000
IAS 19 Sections A and B Liabilities [Member]
Disclosure of defined benefit plans [Line Items]
IAS 19 liabilities (bn)	£ 40.5
IAS 19 Section C Liabilities [Member]
Disclosure of defined benefit plans [Line Items]
IAS 19 liabilities (bn)	18.4
Deferred Members [Member]
Disclosure of defined benefit plans [Line Items]
IAS 19 liabilities (bn)	£ 23.1
Total number of members | Member	83,000
Deferred Members [Member] | IAS 19 Sections A and B Liabilities [Member]
Disclosure of defined benefit plans [Line Items]
IAS 19 liabilities (bn)	£ 9
Deferred Members [Member] | IAS 19 Section C Liabilities [Member]
Disclosure of defined benefit plans [Line Items]
IAS 19 liabilities (bn)	14.1
Pensioners [Member]
Disclosure of defined benefit plans [Line Items]
IAS 19 liabilities (bn)	£ 35.8
Total number of members | Member	205,000
Pensioners [Member] | IAS 19 Sections A and B Liabilities [Member]
Disclosure of defined benefit plans [Line Items]
IAS 19 liabilities (bn)	£ 31.5
Pensioners [Member] | IAS 19 Section C Liabilities [Member]
Disclosure of defined benefit plans [Line Items]
IAS 19 liabilities (bn)	£ 4.3

Retirement Benefit Plan - Sum_8

Retirement Benefit Plan - Summary of Analysis of Membership (Parenthetical) (Detail)	12 Months Ended
	Mar. 31, 2019Member
BT Pension Scheme [Member]
Disclosure of defined benefit plans [Line Items]
Number of members in pension plan	50

Retirement Benefit Plan - Sum_9

Retirement Benefit Plan - Summary of Fair Value of Assets of BTPS Analysed by Asset Category (Detail) - BT Pension Scheme [Member] - GBP (£) £ in Billions		Mar. 31, 2019	Mar. 31, 2018
Disclosure of defined benefit plans [Line Items]
Total	[1]	100.00%	100.00%
Private Equity [Member]
Disclosure of defined benefit plans [Line Items]
Total	[1]	3.00%	4.00%
UK Equity [Member]
Disclosure of defined benefit plans [Line Items]
Total	[1]	1.00%	1.00%
Overseas Developed Equity [Member]
Disclosure of defined benefit plans [Line Items]
Total	[1]	15.00%	16.00%
Emerging Markets Equity [Member]
Disclosure of defined benefit plans [Line Items]
Total	[1]	2.00%	1.00%
UK Property [Member]
Disclosure of defined benefit plans [Line Items]
Total	[1]	7.00%	8.00%
Overseas Property [Member]
Disclosure of defined benefit plans [Line Items]
Total	[1]	2.00%	2.00%
Absolute Return [Member]
Disclosure of defined benefit plans [Line Items]
Total	[1],[2]	2.00%	3.00%
Non Core Credit [Member]
Disclosure of defined benefit plans [Line Items]
Total	[1],[3]	7.00%	7.00%
Mature Infrastructure [Member]
Disclosure of defined benefit plans [Line Items]
Total	[1]	3.00%	3.00%
UK Index Linked Government Bonds [Member]
Disclosure of defined benefit plans [Line Items]
Total	[1]	25.00%	25.00%
Global Investment Grade Credit [Member]
Disclosure of defined benefit plans [Line Items]
Total	[1]	27.00%	20.00%
Cash Balances [Member]
Disclosure of defined benefit plans [Line Items]
Total	[1]	5.00%	7.00%
Longevity Insurance Contract [Member]
Disclosure of defined benefit plans [Line Items]
Total	[1],[4]	(1.00%)	(1.00%)
Other [Member]
Disclosure of defined benefit plans [Line Items]
Total	[1],[5]	2.00%	4.00%
At Fair Value [Member]
Disclosure of defined benefit plans [Line Items]
Total assets £bn	[1]	£ 52.2	£ 49.9
of which quoted £bn	[1],[6]	33.2	29.7
At Fair Value [Member] | Private Equity [Member]
Disclosure of defined benefit plans [Line Items]
Total assets £bn	[1]	1.5	1.9
At Fair Value [Member] | UK Equity [Member]
Disclosure of defined benefit plans [Line Items]
Total assets £bn	[1]	0.5	0.5
of which quoted £bn	[1],[6]	0.4	0.5
At Fair Value [Member] | Overseas Developed Equity [Member]
Disclosure of defined benefit plans [Line Items]
Total assets £bn	[1]	7.7	7.8
of which quoted £bn	[1],[6]	7.3	7.3
At Fair Value [Member] | Emerging Markets Equity [Member]
Disclosure of defined benefit plans [Line Items]
Total assets £bn	[1]	1.1	0.5
of which quoted £bn	[1],[6]	1.1	0.4
At Fair Value [Member] | UK Property [Member]
Disclosure of defined benefit plans [Line Items]
Total assets £bn	[1]	3.5	3.9
At Fair Value [Member] | Overseas Property [Member]
Disclosure of defined benefit plans [Line Items]
Total assets £bn	[1]	1.1	1.2
At Fair Value [Member] | Absolute Return [Member]
Disclosure of defined benefit plans [Line Items]
Total assets £bn	[1],[2]	1.2	1.5
At Fair Value [Member] | Non Core Credit [Member]
Disclosure of defined benefit plans [Line Items]
Total assets £bn	[1],[3]	3.8	3.4
of which quoted £bn	[1],[3],[6]	1.1	1
At Fair Value [Member] | Mature Infrastructure [Member]
Disclosure of defined benefit plans [Line Items]
Total assets £bn	[1]	1.4	1.4
At Fair Value [Member] | UK Index Linked Government Bonds [Member]
Disclosure of defined benefit plans [Line Items]
Total assets £bn	[1]	13.2	12.5
of which quoted £bn	[1],[6]	13.2	12.5
At Fair Value [Member] | Global Investment Grade Credit [Member]
Disclosure of defined benefit plans [Line Items]
Total assets £bn	[1]	14.3	10
of which quoted £bn	[1],[6]	10.1	8
At Fair Value [Member] | Cash Balances [Member]
Disclosure of defined benefit plans [Line Items]
Total assets £bn	[1]	2.7	3.8
At Fair Value [Member] | Longevity Insurance Contract [Member]
Disclosure of defined benefit plans [Line Items]
Total assets £bn	[1],[4]	(0.7)	(0.4)
At Fair Value [Member] | Other [Member]
Disclosure of defined benefit plans [Line Items]
Total assets £bn	[1],[5]	£ 0.9	£ 1.9
[1]	At 31 March 2019, the Scheme did not hold any equity issued by the group (2017/18: £3m). The Scheme also held £2,154m (2017/18: £10m) of bonds issued by the group, reflecting the BTPS fully subscribing to £2bn of bonds issued by BT in June 2018 following agreement of the 2017 funding valuation.
[2]	This allocation seeks to generate returns irrespective of the direction of markets. Managers within this allocation will typically manage their portfolios without close regard to a specific market benchmark.
[3]	This allocation includes a range of credit investments, including emerging market, sub-investment grade and unrated credit. The allocation seeks to exploit investment opportunities within credit markets using the expertise of a range of specialist investment managers.
[4]	The Trustee has hedged some of the Scheme’s longevity risk through a longevity insurance contract which was entered into in 2014. The value reflects experience to date on the contract from higher than expected deaths. This amount partly offsets a reduction which would be recognised in the Scheme’s liabilities over time.
[5]	Includes collateral posted in relation to derivatives held by the Scheme.
[6]	Assets with a quoted price in an active market.

Retirement Benefit Plan - Su_10

Retirement Benefit Plan - Summary of Fair Value of Assets of BTPS Analysed by Asset Category (Parenthetical) (Detail) - BT Pension Scheme [Member] - GBP (£) £ in Millions, shares in Millions	Mar. 31, 2019	Mar. 31, 2018
Disclosure of defined benefit plans [Line Items]
Ordinary shares held under scheme		3
Index-linked bonds held under scheme	£ 2,154	£ 10
Bonds subscribed	£ 2,000

Retirement Benefit Plan - Su_11

Retirement Benefit Plan - Summary of Approach Used to Set the Key IAS 19 Assumptions (Detail) - BT Pension Scheme [Member]	12 Months Ended
	Mar. 31, 2019
Actuarial Assumption of Discount Rates [Member]
Disclosure of defined benefit plans [Line Items]
Discount rate	IAS 19 requires that the discount rate is determined by reference to market yields at the reporting date on high quality corporate bonds. The currency and term of these should be consistent with the currency and estimated term of the pension obligations. The assumption is calculated by applying the projected BTPS benefit cash flows to a corporate bond yield curve constructed by our external actuary based on the yield on AA-rated corporate bonds. In setting the yield curve, judgement is required on the selection of appropriate bonds to be included in the universe and the approach used to then derive the yield curve.
Actuarial Assumption of Expected Rates Off Retail Prices Index Inflation [Member]
Disclosure of defined benefit plans [Line Items]
Discount rate	The RPI inflation assumption is set using an inflation curve derived from market yields on government bonds, weighted by projected BTPS benefit cash flows, and making an adjustment for an inflation risk premium (to reflect the extra premium paid by investors for inflation protection), which is currently assumed to be 20bps.
Actuarial Assumption of Expected Rates of Consumer Prices Index Inflation [Member]
Disclosure of defined benefit plans [Line Items]
Discount rate	CPI is assessed at a margin below RPI taking into account market forecasts and independent estimates of the expected difference.
Actuarial Assumption of Expected Rates of Pension Increases [Member]
Disclosure of defined benefit plans [Line Items]
Discount rate	Benefits are assumed to increase in line with the RPI or CPI inflation assumptions, based on the relevant index for increasing benefits, as prescribed by the rules of the BTPS and summarised above.
Actuarial Assumption of Mortality Rates [Member]
Disclosure of defined benefit plans [Line Items]
Discount rate	The longevity assumption takes into account: – the actual mortality experience of the BTPS pensioners, based on a formal review conducted at the 2014 triennial funding valuation – future improvements in longevity based on a model published by UK actuarial profession’s Continuous Mortality Investigation (using the CMI 2017 Mortality Projections model with a 1.25% per year long-term improvement parameter)

Retirement Benefit Plan - Su_12

Retirement Benefit Plan - Summary of Approach Used to Set the Key IAS 19 Assumptions (Parenthetical) (Detail)	12 Months Ended
	Mar. 31, 2019
Disclosure Of Defined Benefit Plans [Abstract]
Mortality Projections model, long-term improvement parameter, per year	1.25%

Retirement Benefit Plan - Su_13

Retirement Benefit Plan - Summary of Key Financial Assumptions Used to Measure Liabilities of BTPS (Detail)	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Real Rates [Member]
Disclosure of defined benefit plans [Line Items]
Rate used to discount liabilities	(0.87%)	(0.44%)	(0.78%)
Real Rates [Member] | Consumer Price Index
Disclosure of defined benefit plans [Line Items]
Inflation – increase	(1.00%)	(1.10%)	(1.20%)
Nominal Rates [Member]
Disclosure of defined benefit plans [Line Items]
Rate used to discount liabilities	2.35%	2.65%	2.40%
Nominal Rates [Member] | Retail Price Index
Disclosure of defined benefit plans [Line Items]
Inflation – increase	3.25%	3.10%	3.20%
Nominal Rates [Member] | Consumer Price Index
Disclosure of defined benefit plans [Line Items]
Inflation – increase	2.25%	2.00%	2.00%

Retirement Benefit Plan - Su_14

Retirement Benefit Plan - Summary of Key Financial Assumptions Used to Measure Liabilities of BTPS (Parenthetical) (Detail)	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Defined Benefit Plans [Abstract]
Minimum assumed real rate for next four fiscal period	0.10%
Maximum assumed real rate for next four fiscal period		0.10%
Maximum Assumed Real Rate			0.50%

Retirement Benefit Plan - Su_15

Retirement Benefit Plan - Summary of Forecast Life Expectancies for BTPS Members Aged 60 (Detail)	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Male in Lower Pay Bracket [Member]
Disclosure of defined benefit plans [Line Items]
Number of years	25 years 8 months 12 days	25 years 9 months 18 days
Male in Medium Pay Bracket [Member]
Disclosure of defined benefit plans [Line Items]
Number of years	27 years	27 years 1 month 6 days
Male in Higher Pay Bracket [Member]
Disclosure of defined benefit plans [Line Items]
Number of years	28 years 6 months	28 years 6 months
Female in Lower Pay Bracket [Member]
Disclosure of defined benefit plans [Line Items]
Number of years	28 years 6 months	28 years 6 months
Female in Higher Pay Bracket [Member]
Disclosure of defined benefit plans [Line Items]
Number of years	28 years 8 months 12 days	28 years 8 months 12 days
Average Improvement for a Member Retiring at Age 60 in 10 Years Time [Member]
Disclosure of defined benefit plans [Line Items]
Number of years	8 months 12 days	8 months 12 days

Retirement Benefit Plans - Summ

Retirement Benefit Plans - Summary of Assessed Potential Negative Impact of Key Risk (Detail)	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disclosure Of Defined Benefit Plans [Abstract]
Fall in discount rate	1.10%	1.10%
Increase to inflation rate	0.70%	0.70%
Fall in equity markets	30.00%
Increase to life expectancy	1 year 3 months	1 year 4 months 6 days

Retirement Benefit Plan - Su_16

Retirement Benefit Plan - Summary of Two Most Recent Triennial Valuations (Detail) - BTPS [Member] - GBP (£) £ in Billions	Jun. 30, 2017	Jun. 30, 2014
Disclosure of defined benefit plans [Line Items]
BTPS liabilities	£ (60.4)	£ (47.2)
Market value of BTPS assets	49.1	40.2
Funding deficit	£ (11.3)	£ (7)
Percentage of accrued benefits covered by BTPS assets at valuation date	81.30%	85.20%
Percentage of accrued benefits on a solvency basis covered by the BTPS assets at the valuation date	62.20%	63.00%

Retirement Benefit Plan - Su_17

Retirement Benefit Plan - Summary of Prudent Long-Term Assumptions (Detail) - BTPS [Member]	Jun. 30, 2017	Jun. 30, 2014
Nominal Rates [Member]
Disclosure of defined benefit plans [Line Items]
Average single equivalent discount rate	2.60%	4.50%
Average long-term increase in RPI	3.40%	3.50%
Average long-term increase in CPI	2.40%	2.50%
Real Rates [Member]
Disclosure of defined benefit plans [Line Items]
Average single equivalent discount rate	(0.80%)	1.00%
Average long-term increase in CPI	(1.00%)	(1.00%)

Retirement Benefit Plans - Sche

Retirement Benefit Plans - Schedule of Payments Made to BTPS (Detail) - BTPS [Member] - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disclosure of defined benefit plans [Line Items]
Regular contributions by employer	£ 33	£ 248
Deficit contributions	2,000	850
Total contributions in the year	£ 2,033	£ 1,098

Retirement Benefit Plans - Sc_2

Retirement Benefit Plans - Schedule of Future Deficit Payments (Detail) - BTPS [Member] £ in Millions	12 Months Ended
	Mar. 31, 2019GBP (£)
2020 [Member]
Disclosure Of Deficit Contribution Plans [Line Items]
Deficit contribution (£m)	£ 1,250
2021 [Member]
Disclosure Of Deficit Contribution Plans [Line Items]
Deficit contribution (£m)	900
2022 [Member]
Disclosure Of Deficit Contribution Plans [Line Items]
Deficit contribution (£m)	900
2023 [Member]
Disclosure Of Deficit Contribution Plans [Line Items]
Deficit contribution (£m)	907
2024 [Member]
Disclosure Of Deficit Contribution Plans [Line Items]
Deficit contribution (£m)	907
2025 [Member]
Disclosure Of Deficit Contribution Plans [Line Items]
Deficit contribution (£m)	907
2026 [Member]
Disclosure Of Deficit Contribution Plans [Line Items]
Deficit contribution (£m)	907
2027 [Member]
Disclosure Of Deficit Contribution Plans [Line Items]
Deficit contribution (£m)	907
2028 [Member]
Disclosure Of Deficit Contribution Plans [Line Items]
Deficit contribution (£m)	907
2029 [Member]
Disclosure Of Deficit Contribution Plans [Line Items]
Deficit contribution (£m)	907
2030 [Member]
Disclosure Of Deficit Contribution Plans [Line Items]
Deficit contribution (£m)	£ 907

Retirement Benefit Plans - Sc_3

Retirement Benefit Plans - Schedule of Future Deficit Payments to BTPS (Parenthetical) (Detail) - BTPS [Member] - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disclosure Of Deficit Contribution Plans [Line Items]
Deficit contribution (£m)	£ 2,033	£ 1,098
Payable by 30 June 2020 [Member]
Disclosure Of Deficit Contribution Plans [Line Items]
Deficit contribution (£m)	400
Payable by 30 June 2021 [Member]
Disclosure Of Deficit Contribution Plans [Line Items]
Deficit contribution (£m)	£ 200

Share-Based Payments - Summary

Share-Based Payments - Summary of Plans and Analysis of Total Charge by Type of Award (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Share/Save Plans	£ 67	£ 84	£ 57
Employee Saveshare Plans [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Share/Save Plans	38	42	40
Incentive Share Plan [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Share/Save Plans	6	16
Deferred Bonus Plan [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Share/Save Plans	6	4	9
Retention Share Plan [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Share/Save Plans	£ 17	21	£ 8
Other Plans [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Share/Save Plans		£ 1

Share-Based Payments - Addition

Share-Based Payments - Additional Information (Detail)	12 Months Ended
	Mar. 31, 2019GBP (£)yr	Mar. 31, 2018GBP (£)	Mar. 31, 2017GBP (£)
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Share-based arrangements, term (in years) | yr	3
Share-based awards, awards grant date	in 2018/19, 2017/18 and 2016/17
Percentage of each award linked to total shareholder return	40.00%
Percentage of each award linked to three-year cumulative free cash flow measure	40.00%
Percentage of growth in underlying revenue excluding transit	20.00%
Cumulative period for free cash flow measure	3 years
Weighted average share price	£ 2.49	£ 3.11	£ 3.57
Options pricing model	Binomial options pricing model
Options pricing model, valuation method	Monte Carlo simulations
Share-based awards, performance period	three-year
Share-based awards, expected life after vesting date	3 months
Employee Saveshare Plans [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Savings-related share option plan saving period basis	Monthly
Share-based awards, term	Over a three or five-year period
Share-based awards, exercise period	6 months
Weighted average share price	£ 2.08	2.96	4.22
Employee Saveshare Plans [Member] | Bottom of Range [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Share-based arrangements, term (in years) | yr	3
Employee Saveshare Plans [Member] | Top of Range [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Share-based arrangements, term (in years) | yr	5
Employee Saveshare Plans [Member] | Five Year Plans [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Percentage of discount set to market price	20.00%
Employee Saveshare Plans [Member] | Three Year Plans [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Percentage of discount set to market price	10.00%
Deferred Bonus Plan [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Weighted average share price	£ 2.09	2.82	4.21
Retention Share Plan [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Weighted average share price	£ 2.17	£ 2.82	£ 4.17

Share-Based Payments - Summar_2

Share-Based Payments - Summary of Movements in Employee Saveshare Options - Movement in Number of Share Options (Detail) - Employee Saveshare Plans [Member] - Option Option in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Outstanding at 1 April	175	189	197
Granted	80	69	44
Forfeited	(44)	(41)	(18)
Exercised	(1)	(30)	(33)
Expired	(20)	(12)	(1)
Outstanding at 31 March	190	175	189

Share-Based Payments - Summar_3

Share-Based Payments - Summary of Movements in Employee Saveshare Options - Weighted Average Share Price (Detail) - Employee Saveshare Plans [Member] - GBP (£)	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Outstanding at 1 April	£ 3.06	£ 3.13	£ 2.87
Granted	1.75	2.50	3.62
Forfeited	2.98	3.28	3.45
Exercised	2.47	1.69	2.08
Expired	2.94	3.53	3.45
Outstanding at 31 March	2.54	3.06	3.13
Exercisable at 31 March	£ 2.49	£ 3.20	£ 2.37

Share-Based Payments - Summaris

Share-Based Payments - Summarises Information Relating to Options Outstanding and Exercisable Under Employee Saveshare Plans (Detail) - Employee Saveshare Plans [Member] Option in Millions	Mar. 31, 2019GBP (£)Optionmo	Mar. 31, 2018GBP (£)Option	Mar. 31, 2017GBP (£)Option	Mar. 31, 2016GBP (£)Option
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Weighted average exercise price	£ 2.54	£ 3.06	£ 3.13	£ 2.87
Number of outstanding options | Option	189	175	189	197
Weighted average remaining contractual life | mo	34
2019 [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Weighted average exercise price	£ 3.33
Number of outstanding options | Option	40
Weighted average remaining contractual life | mo	10
2020 [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Weighted average exercise price	£ 3.05
Number of outstanding options | Option	34
Weighted average remaining contractual life | mo	22
2021 [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Weighted average exercise price	£ 2.32
Number of outstanding options | Option	43
Weighted average remaining contractual life | mo	34
2022 [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Weighted average exercise price	£ 2.43
Number of outstanding options | Option	29
Weighted average remaining contractual life | mo	46
2023 [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Weighted average exercise price	£ 1.70
Number of outstanding options | Option	43
Weighted average remaining contractual life | mo	58
Bottom of Range [Member] | 2019 [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Exercise price per share	£ 3.19
Bottom of Range [Member] | 2020 [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Exercise price per share	2.43
Top of Range [Member] | 2019 [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Exercise price per share	3.97
Top of Range [Member] | 2020 [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Exercise price per share	3.76
Top of Range [Member] | 2021 [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Exercise price per share	2.43
Top of Range [Member] | 2022 [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Exercise price per share	£ 1.70

Share-Based Payments - Summar_4

Share-Based Payments - Summary of Movements in Executive Share Plan Awards (Detail) - Executive Share Plans [Member] shares in Millions, Instrument in Millions	12 Months Ended
	Mar. 31, 2019Instrumentshares
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
At 31 March 2018	72
Awards granted	44
Awards vested	(8)
Awards lapsed	(20)
Dividend shares reinvested | shares	5
At 31 March 2019	93
Incentive Share Plan [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
At 31 March 2018	54
Awards granted	33
Awards lapsed	(18)
Dividend shares reinvested | shares	5
At 31 March 2019	74
Deferred Bonus Plan [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
At 31 March 2018	6
Awards granted	4
Awards vested	(1)
Awards lapsed	(1)
At 31 March 2019	8
Retention Share Plan [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
At 31 March 2018	12
Awards granted	7
Awards vested	(7)
Awards lapsed	(1)
At 31 March 2019	11

Share-Based Payments - Summar_5

Share-Based Payments - Summary of Fair Values and Key Assumptions Used for Valuing Grants Made Under Employee Saveshare Plans and ISP (Detail) - GBP (£)	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Weighted average share price	£ 2.49	£ 3.11	£ 3.57
Employee Saveshare Plans [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Weighted average fair value	0.41	0.56	0.72
Weighted average share price	2.08	2.96	4.22
Weighted average exercise price	£ 1.75	£ 2.50	£ 3.62
Employee Saveshare Plans [Member] | Bottom of Range [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Expected dividend yield	3.47%	3.12%	2.90%
Risk free rates	0.74%	0.10%	0.50%
Expected volatility	23.30%	23.10%	19.00%
Employee Saveshare Plans [Member] | Top of Range [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Expected dividend yield	3.83%	3.21%	3.40%
Risk free rates	1.07%	0.20%	0.80%
Expected volatility	25.80%	24.30%	21.50%
Incentive Share Plan [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Weighted average fair value	£ 1.56	£ 2.02	£ 3.28
Weighted average share price	£ 2.11	£ 2.81	£ 4.26
Risk free rates	0.70%	0.20%	0.60%
Expected volatility	23.50%	23.60%	21.80%

Investments - Summary of Invest

Investments - Summary of Investments (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Non-current assets
Fair value through other comprehensive income	£ 48
Available-for-sale		£ 46	£ 37
Amounts owed by ultimate parent company	3,029	2,983	1,371
Amounts owed by parent company	10,436	10,318	10,191
Fair value through profit or loss	6	7	7
Non-current assets	13,519	13,354	11,606
Current assets
Available-for-sale		2,575	1,437
Amounts owed by ultimate parent company	61	34	28
Amounts owed by parent company	211	168	192
Investment held at amortised cost	3,214
Loans and receivables		447	83
Current assets	£ 3,486	£ 3,224	£ 1,740

Investments - Additional Inform

Investments - Additional Information (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure of investment [line items]
Investments in liquidity funds	£ 2,522	£ 2,575	£ 1,437
Available-for-sale investments		2,621	1,474
Level 2 [Member]
Disclosure of investment [line items]
Available-for-sale investments		2,575	1,437
Level 3 [Member]
Disclosure of investment [line items]
Available-for-sale investments		14	16
Investments classified as fair value through comprehensive income	10
Sterling [Member]
Disclosure of investment [line items]
Investments in term deposits denominated in currencies	2,687	416	35
Sterling [Member] | Level 2 [Member]
Disclosure of investment [line items]
Available-for-sale investments		2,180	900
USD [Member]
Disclosure of investment [line items]
Investments in term deposits denominated in currencies	26	27	30
Euros [Member]
Disclosure of investment [line items]
Investments in term deposits denominated in currencies	499
Euros [Member] | Level 2 [Member]
Disclosure of investment [line items]
Available-for-sale investments		395	537
Other Currencies [Member]
Disclosure of investment [line items]
Investments in term deposits denominated in currencies	£ 2	£ 4	£ 18

Investments - Fair Value Hierar

Investments - Fair Value Hierarchy of Investments (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Non-current and current investments
Fair value through other comprehensive income	£ 48
Available-for-sale		£ 2,621	£ 1,474
Fair value through profit or loss	6	7	7
Total	54	2,628	1,481
Level 1 [Member]
Non-current and current investments
Fair value through other comprehensive income	38
Available-for-sale		32	21
Fair value through profit or loss	6	7	7
Total	44	39	28
Level 2 [Member]
Non-current and current investments
Available-for-sale		2,575	1,437
Total		2,575	1,437
Level 3 [Member]
Non-current and current investments
Fair value through other comprehensive income	10
Available-for-sale		14	16
Total	£ 10	£ 14	£ 16

Cash and Cash Equivalents - Sum

Cash and Cash Equivalents - Summary of Cash and Cash Equivalents (Detail) - GBP (£) £ in Millions		Mar. 31, 2019	Apr. 01, 2018	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Disclosure of cash and cash equivalents [line items]
Cash at bank and in hand		£ 493		£ 439	£ 467
Cash equivalents
Total cash and cash equivalents		1,664	£ 521	521	526
Bank overdrafts		(72)		(29)	(17)
Cash and cash equivalents per the cash flow statement	[1]	1,592		492	509	£ 452
Financial Assets At Amortised Cost Category [Member]
Cash equivalents
Cash equivalents		1,171
Loans And Receivables Category [Member]
Cash equivalents
Cash equivalents				82	59
US Deposits [Member] | Financial Assets At Amortised Cost Category [Member]
Cash equivalents
Other deposits		3
US Deposits [Member] | Loans And Receivables Category [Member]
Cash equivalents
Other deposits				26	32
UK Deposits [Member] | Financial Assets At Amortised Cost Category [Member]
Cash equivalents
Other deposits		1,132
UK Deposits [Member] | Loans And Receivables Category [Member]
Cash equivalents
Other deposits				31	1
Other Deposits [Member] | Financial Assets At Amortised Cost Category [Member]
Cash equivalents
Other deposits		£ 36
Other Deposits [Member] | Loans And Receivables Category [Member]
Cash equivalents
Other deposits				£ 25	£ 26
[1]	Net of bank overdrafts of £72m (2017/18: £29m, 2016/17: £17m).

Cash and Cash Equivalents - Add

Cash and Cash Equivalents - Additional Information (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Cash and Cash Equivalents [Line Items]
Restricted cash	£ 44	£ 32	£ 43
Held In Countries Prevent From Accessing Cash Balance [Member]
Cash and Cash Equivalents [Line Items]
Restricted cash	40	29	41
Held in Escrow Accounts or in Commercial Arrangements [Member]
Cash and Cash Equivalents [Line Items]
Restricted cash	£ 4	£ 3	£ 2

Loans and Other Borrowings - Ad

Loans and Other Borrowings - Additional Information (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Detailed Information About Borrowings [Line Items]
Increase in external gross debt	£ 2,737
Fair value of listed bonds and other long-term borrowings	18,977	£ 15,336	£ 13,896
Fair value of finance leases	206	223	229
Principal Repayment at Hedged Rates [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Principal repayments of loans and borrowings at hedged rate	17,970	14,219	12,138
At Fair Value [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Fair value of listed bonds and other long-term borrowings	17,785	14,878	13,496
Fair value of finance leases	£ 251	£ 253	£ 273

Loans and Other Borrowings - Su

Loans and Other Borrowings - Summary of Key Components of External Gross Debt (Detail) - Gross Carrying Amount [Member] £ in Millions	12 Months Ended
	Mar. 31, 2019GBP (£)
Disclosure Of Detailed Information About Borrowings [Line Items]
At 1 April 2018 £m	£ 13,175
Issuance/ (maturities) £m	2,719
Foreign exchange £m	(17)
Accrued interest movements £m	35
At 31 March 2019 £m	15,912
2019 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
At 1 April 2018 £m	2,281
Issuance/ (maturities) £m	(1,423)
Fair value movements £m	(8)
Foreign exchange £m	(97)
Transfer to within one year £m	1,281
Accrued interest movements £m	66
At 31 March 2019 £m	2,100
Over 12 Months [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
At 1 April 2018 £m	11,994
Issuance/ (maturities) £m	3,972
Fair value movements £m	(11)
Foreign exchange £m	(102)
Transfer to within one year £m	(1,111)
Accrued interest movements £m	34
At 31 March 2019 £m	14,776
Cash Flows From Derivatives Related to Net Debt [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Issuance/ (maturities) £m	124
Transfer to within one year £m	(124)
Overdrafts [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Issuance/ (maturities) £m	46
Transfer to within one year £m	(46)
Impact of Cross-currency Swaps [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
At 1 April 2018 £m	(874)
Foreign exchange £m	182
Accrued interest movements £m	(9)
At 31 March 2019 £m	(701)
Removal of the Accrued Interest and Fair Value [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
At 1 April 2018 £m	(226)
Fair value movements £m	19
Accrued interest movements £m	(56)
At 31 March 2019 £m	£ (263)

Loans and Other Borrowings - _2

Loans and Other Borrowings - Summary of Reconciliation From Most Directly Comparable IFRS Measure to Net Debt (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	£ 15,953	£ 13,491	£ 11,405
Finance leases	206	223	229
Other loans	645	532	710
Bank overdrafts (note 22)	72	29	17
Amounts due to ultimate company	2,101	1,061	1,183
Total other loans and borrowings	2,818	1,622	2,262
Total loans and borrowings	18,977	15,336	13,896
6.625% Bond Due June 2017 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds			526
5.95% Bond Due January 2018 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds			891
3.25% Bond Due August 2018 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds		541	539
2.35% Bond Due February 2019 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds		572	642
1.125% Bond Due June 2019 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	869	883	863
8.625% Bond Due March 2020 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	300	300	300
0.625% Bond Due March 2021 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	1,289	1,309	1,282
4.38% Bond Due March 2019 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds		455	460
0.5% Bond Due June 2022 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	495	502
4.5% Bond Due December 2023 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	524
1.125% Bond Due March 2023 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	946	961	942
0.875% Bond Due September 2023 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	430
1% Bond Due June 2024 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	498	506
1% Bond Due June 2024 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	943	959
3.50% Index Linked Bond Due April 2025 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	433	419	403
1.75% Bond Due March 2026 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	1,118	1,137	1,113
2.125% Bond Due September 2028 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	433
1.5% Bond Due June 2027 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	993	1,009
5.125% Bond Due December 2028 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	542
5.75% Bond Due December 2028 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	710	721	731
9.625% Bond Due December 2030 (Minimum 8.625%) [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	2,096	1,943	2,191
3.125% Bond Due November 2031 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	502	502
3.64% Bond Due June 2033 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	339
6.375% Bond Due June 2037 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	522	522	522
1.613% Indexed Linked Bond Due June 2033 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	340
3.883% Bond Due June 2039 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	340
1.739% Indexed Linked Bond Due June 2039 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	340
3.924% Bond Due June 2042 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	350
2.21% Bank Loan Due December 2017 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loan due			£ 352
1.774% Indexed Linked Bond Due June 2042 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	351
3.625% Bond Due November 2047 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total listed bonds	£ 250	£ 250

Loans and Other Borrowings - _3

Loans and Other Borrowings - Summary of Reconciliation From Most Directly Comparable IFRS Measure to Net Debt (Parenthetical) (Detail) € in Millions, £ in Millions, $ in Millions	12 Months Ended
	Mar. 31, 2019GBP (£)	Mar. 31, 2018GBP (£)	Mar. 31, 2017GBP (£)	Mar. 31, 2019USD ($)	Mar. 31, 2019EUR (€)	Mar. 31, 2018USD ($)	Mar. 31, 2018EUR (€)	Mar. 31, 2017USD ($)	Mar. 31, 2017EUR (€)
Disclosure Of Detailed Information About Borrowings [Line Items]
Upgrade rating percentage	0.25%
Downgrade rating percentage	0.25%
6.625% Bond Due June 2017 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount			£ 500
Loans and borrowings, interest rate			6.625%					6.625%	6.625%
Loans and borrowings, original currency			GBP
Loans and borrowings, maturity			June 2017
5.95% Bond Due January 2018 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount | $								$ 1,100
Loans and borrowings, interest rate			5.95%					5.95%	5.95%
Loans and borrowings, original currency			USD
Loans and borrowings, maturity			January 2018
3.25% Bond Due August 2018 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount | €							€ 600		€ 600
Loans and borrowings, interest rate		3.25%	3.25%			3.25%	3.25%	3.25%	3.25%
Loans and borrowings, original currency		EUR	EUR
Loans and borrowings, maturity		August 2018	August 2018
2.35% Bond Due February 2019 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount | $						$ 800		$ 800
Loans and borrowings, interest rate		2.35%	2.35%			2.35%	2.35%	2.35%	2.35%
Loans and borrowings, original currency		USD	USD
Loans and borrowings, maturity		February 2019	February 2019
4.38% Bond Due March 2019 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount		£ 450	£ 450
Loans and borrowings, interest rate		4.38%	4.38%			4.38%	4.38%	4.38%	4.38%
Loans and borrowings, original currency		GBP	GBP
Loans and borrowings, maturity		March 2019	March 2019
1.125% Bond Due June 2019 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount | €					€ 1,000		€ 1,000		€ 1,000
Loans and borrowings, interest rate	1.125%	1.125%	1.125%	1.125%	1.125%	1.125%	1.125%	1.125%	1.125%
Loans and borrowings, original currency	EUR	EUR	EUR
Loans and borrowings, maturity	June 2019	June 2019	June 2019
8.625% Bond Due March 2020 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount	£ 300	£ 300	£ 300
Loans and borrowings, interest rate	8.625%	8.625%	8.625%	8.625%	8.625%	8.625%	8.625%	8.625%	8.625%
Loans and borrowings, original currency	GBP	GBP	GBP
Loans and borrowings, maturity	March 2020	March 2020	March 2020
0.625% Bond Due March 2021 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount | €					€ 1,500		€ 1,500		€ 1,500
Loans and borrowings, interest rate	0.625%	0.625%	0.625%	0.625%	0.625%	0.625%	0.625%	0.625%	0.625%
Loans and borrowings, original currency	EUR	EUR	EUR
Loans and borrowings, maturity	March 2021	March 2021	March 2021
0.5% Bond Due June 2022 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount | €					€ 575		€ 575
Loans and borrowings, interest rate	0.50%	0.50%		0.50%	0.50%	0.50%	0.50%
Loans and borrowings, original currency	EUR	EUR
Loans and borrowings, maturity	June 2022	June 2022
1.125% Bond Due March 2023 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount | €					€ 1,100		€ 1,100		€ 1,100
Loans and borrowings, interest rate	1.125%	1.125%	1.125%	1.125%	1.125%	1.125%	1.125%	1.125%	1.125%
Loans and borrowings, original currency	EUR	EUR	EUR
Loans and borrowings, maturity	March 2023	March 2023	March 2023
0.875% Bond Due September 2023 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount | €					€ 500
Loans and borrowings, interest rate	0.875%			0.875%	0.875%
Loans and borrowings, original currency	EUR
Loans and borrowings, maturity	September 2023
4.5% Bond Due December 2023 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount | $				$ 675
Loans and borrowings, interest rate	4.50%			4.50%	4.50%
Loans and borrowings, original currency	USD
Loans and borrowings, maturity	December 2023
1% Bond Due June 2024 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount | €					€ 575		€ 575
Loans and borrowings, interest rate	1.00%	1.00%		1.00%	1.00%	1.00%	1.00%
Loans and borrowings, original currency	EUR	EUR
Loans and borrowings, maturity	June 2024	June 2024
1% Bond Due June 2024 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount | €					€ 1,100		€ 1,100
Loans and borrowings, interest rate	1.00%	1.00%		1.00%	1.00%	1.00%	1.00%
Loans and borrowings, original currency	EUR	EUR
Loans and borrowings, maturity	November 2024	November 2024
3.50% Index Linked Bond Due April 2025 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount	£ 250	£ 250	£ 250
Loans and borrowings, interest rate	3.50%	3.50%	3.50%	3.50%	3.50%	3.50%	3.50%	3.50%	3.50%
Loans and borrowings, original currency	GBP	GBP	GBP
Loans and borrowings, maturity	April 2025	April 2025	April 2025
1.75% Bond Due March 2026 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount | €					€ 1,300		€ 1,300		€ 1,300
Loans and borrowings, interest rate	1.75%	1.75%	1.75%	1.75%	1.75%	1.75%	1.75%	1.75%	1.75%
Loans and borrowings, original currency	EUR	EUR	EUR
Loans and borrowings, maturity	March 2026	March 2026	March 2026
1.5% Bond Due June 2027 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount | €					€ 1,150		€ 1,150
Loans and borrowings, interest rate	1.50%	1.50%		1.50%	1.50%	1.50%	1.50%
Loans and borrowings, original currency	EUR	EUR
Loans and borrowings, maturity	June 2027	June 2027
2.125% Bond Due September 2028 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount | €					€ 500
Loans and borrowings, interest rate	2.125%			2.125%	2.125%
Loans and borrowings, original currency	EUR
Loans and borrowings, maturity	September 2028
5.125% Bond Due December 2028 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount | $				$ 700
Loans and borrowings, interest rate	5.125%			5.125%	5.125%
Loans and borrowings, original currency	USD
Loans and borrowings, maturity	December 2028
5.75% Bond Due December 2028 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount	£ 600	£ 600	£ 600
Loans and borrowings, interest rate	5.75%	5.75%	5.75%	5.75%	5.75%	5.75%	5.75%	5.75%	5.75%
Loans and borrowings, original currency	GBP	GBP	GBP
Loans and borrowings, maturity	December 2028	December 2028	December 2028
9.625% Bond Due December 2030 (Minimum 8.625%) [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount | $				$ 2,670		$ 2,670		$ 2,670
Loans and borrowings, interest rate	9.625%	9.625%	9.625%	9.625%	9.625%	9.625%	9.625%	9.625%	9.625%
Loans and borrowings, original currency	USD	USD	US$
Loans and borrowings, maturity	December 2030	December 2030	December 2030
9.625% Bond Due December 2030 (Minimum 8.625%) [Member] | Bottom of Range [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, interest rate	8.625%	8.625%	8.625%	8.625%	8.625%	8.625%	8.625%	8.625%	8.625%
3.125% Bond Due November 2031 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount	£ 500	£ 500
Loans and borrowings, interest rate	3.125%	3.125%		3.125%	3.125%	3.125%	3.125%
Loans and borrowings, original currency	GBP	GBP
Loans and borrowings, maturity	November 2031	November 2031
3.64% Bond Due June 2033 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount	£ 330
Loans and borrowings, interest rate	3.64%			3.64%	3.64%
Loans and borrowings, original currency	GBP
Loans and borrowings, maturity	June 2033
1.613% Indexed Linked Bond Due June 2033 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount	£ 330
Loans and borrowings, interest rate	1.613%			1.613%	1.613%
Loans and borrowings, original currency	GBP
Loans and borrowings, maturity	June 2033
6.375% Bond Due June 2037 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount	£ 500	£ 500	£ 500
Loans and borrowings, interest rate	6.375%	6.375%	6.375%	6.375%	6.375%	6.375%	6.375%	6.375%	6.375%
Loans and borrowings, original currency	GBP	GBP	GBP
Loans and borrowings, maturity	June 2037	June 2037	June 2037
3.924% Bond Due June 2042 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount	£ 340
Loans and borrowings, original currency	GBP
Loans and borrowings, maturity	June 2042
Loans and borrowings, LIBOR interest rate	3.924%			3.924%	3.924%
1.774% Indexed Linked Bond Due June 2042 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount	£ 340
Loans and borrowings, interest rate	1.774%			1.774%	1.774%
Loans and borrowings, original currency	GBP
Loans and borrowings, maturity	June 2042
3.883% Bond Due June 2039 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount	£ 330
Loans and borrowings, interest rate	3.883%			3.883%	3.883%
Loans and borrowings, original currency	GBP
Loans and borrowings, maturity	June 2039
1.739% Indexed Linked Bond Due June 2039 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount	£ 330
Loans and borrowings, interest rate	1.739%			1.739%	1.739%
Loans and borrowings, original currency	GBP
Loans and borrowings, maturity	June 2039
3.625% Bond Due November 2047 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount	£ 250	£ 250
Loans and borrowings, interest rate	3.625%	3.625%		3.625%	3.625%	3.625%	3.625%
Loans and borrowings, original currency	GBP	GBP
Loans and borrowings, maturity	November 2047	November 2047
2.21% Bank Loan Due December 2017 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Loans and borrowings, face amount		£ 350	£ 350
Loans and borrowings, interest rate		2.21%	2.21%			2.21%	2.21%	2.21%	2.21%
Loans and borrowings, maturity		December 2017	December 2017

Loans and Other Borrowings - _4

Loans and Other Borrowings - Summary Of Loans and Other Borrowings (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Apr. 01, 2018	Mar. 31, 2018	Mar. 31, 2017
Current liabilities
Listed bonds	£ 1,367		£ 1,702	£ 1,539
Finance leases	16		18	15
Bank loans				352
Other loans and bank overdrafts	717		561	726
Amounts due to ultimate parent company	1,040		17	159
Total current liabilities	3,140		2,298	2,791
Non-current liabilities
Listed bonds	14,586		11,789	9,866
Finance leases	190		205	214
Other loans				1
Amounts due to ultimate parent company	1,061		1,044	1,024
Total non-current liabilities	15,837	£ 13,038	13,038	11,105
Total	£ 18,977		£ 15,336	£ 13,896

Loans and Other Borrowings - _5

Loans and Other Borrowings - Summary Of Loans and Other Borrowings (Parenthetical) (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Detailed Information About Borrowings [Abstract]
Collateral received on swaps	£ 638	£ 525	£ 702

Loans and Other Borrowings - _6

Loans and Other Borrowings - Summary of Principal Repayments of Loans and Other Borrowings (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017	Apr. 01, 2018
Disclosure Of Detailed Information About Borrowings [Line Items]
Total due for repayment after more than one year	£ 15,837	£ 13,038	£ 11,105	£ 13,038
Total	18,977	15,336	13,896
Carrying Amount [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Within one year, or on demand	3,140	2,289	2,791
Total	18,927	15,263	13,746
Fair value adjustments	50	73	150
Total loans and other borrowings	18,977	15,336	13,896
Effect Of Hedging And Interest [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Within one year, or on demand	(307)	(308)	(523)
Total	(957)	(1,044)	(1,608)
Principal Repayment at Hedged Rates [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Within one year, or on demand	2,833	1,981	2,268
Total	17,970	14,219	12,138
2020 [Member] | Carrying Amount [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total due for repayment after more than one year	1,309	1,192	1,614
2020 [Member] | Effect Of Hedging And Interest [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total due for repayment after more than one year	(133)	(66)	(197)
2020 [Member] | Principal Repayment at Hedged Rates [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total due for repayment after more than one year	1,176	1,126	1,417
2021 [Member] | Carrying Amount [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total due for repayment after more than one year	15	1,332	1,166
2021 [Member] | Effect Of Hedging And Interest [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total due for repayment after more than one year		(154)	(43)
2021 [Member] | Principal Repayment at Hedged Rates [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total due for repayment after more than one year	15	1,178	1,123
2022 [Member] | Carrying Amount [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total due for repayment after more than one year	1,463	18	1,295
2022 [Member] | Effect Of Hedging And Interest [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total due for repayment after more than one year	(89)		(121)
2022 [Member] | Principal Repayment at Hedged Rates [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total due for repayment after more than one year	1,374	18	1,174
2023 [Member] | Carrying Amount [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total due for repayment after more than one year	964	1,489	12
2023 [Member] | Effect Of Hedging And Interest [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total due for repayment after more than one year	33	(111)
2023 [Member] | Principal Repayment at Hedged Rates [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total due for repayment after more than one year	997	1,378	12
2023 [Member] | Carrying Amount [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total due for repayment after more than one year	12,036	8,943	6,868
2023 [Member] | Effect Of Hedging And Interest [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total due for repayment after more than one year	(461)	(405)	(724)
2023 [Member] | Principal Repayment at Hedged Rates [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total due for repayment after more than one year	11,575	8,538	6,144
Over 12 Months [Member] | Carrying Amount [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total due for repayment after more than one year	15,787	12,974	10,955
Over 12 Months [Member] | Effect Of Hedging And Interest [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total due for repayment after more than one year	(650)	(736)	(1,085)
Over 12 Months [Member] | Principal Repayment at Hedged Rates [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Total due for repayment after more than one year	£ 15,137	£ 12,238	£ 9,870

Loans and Other Borrowings - _7

Loans and Other Borrowings - Summary of Obligations Under Finance Leases (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Detailed Information About Borrowings [Line Items]
Amounts payable under finance leases	£ 297	£ 348	£ 368
Less: future finance charges	(95)	(129)	(139)
Fair value adjustments for purchase price adjustment	4	4
Total finance lease obligations	206	223	229
Repayment of outstanding lease obligations	202	219	229
Fair value adjustments for purchase price adjustment	4	4
Total finance lease obligations	206	223	229
2019 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Amounts payable under finance leases	29	33	29
Repayment of outstanding lease obligations	16	18	14
Between Two and Five Years [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Amounts payable under finance leases	109	122	102
Repayment of outstanding lease obligations	66	71	50
2023 [Member]
Disclosure Of Detailed Information About Borrowings [Line Items]
Amounts payable under finance leases	159	193	237
Repayment of outstanding lease obligations	£ 120	£ 130	£ 165

Finance Expense - Summary of Fi

Finance Expense - Summary of Finance Expense and Income (Detail) - GBP (£) £ in Millions		12 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Interest on:
Financial liabilities at amortised cost and associated derivatives		£ 582	£ 478	£ 567
Finance leases		13	16	15
Derivatives			14	12
Fair value movements on derivatives not in a designated hedge relationship		(3)	1	(2)
Reclassification of cash flow hedge from other comprehensive income		45	34	(1)
Unwinding of discount on provisions		14	15	16
Interest payable on ultimate parent company borrowings		43	18	25
Total finance expense		833	794	842
Interest on available-for-sale investments			5	6
Interest on loans and receivables		34	7	7
Interest income on loans to immediate and ultimate parent company		272	203	219
Total finance income		306	215	232
Net finance expense		527	579	610
Before Specific Items [Member]
Interest on:
Total finance expense		694	576	632
Total finance income		306	215	232
Net finance expense		388	361	400
Specific Items [Member]
Interest on:
Total finance expense	[1]	139	218	210
Net finance expense	[1]	£ 139	£ 218	£ 210
[1]	For a definition of specific items, see page [210]. An analysis of specific items is provided in note 10.

Financial Instruments and Ris_3

Financial Instruments and Risk Management - Additional Information (Detail) - GBP (£)	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016	Apr. 01, 2018
Disclosure of Nature and Extent of Risks Arising From Financial Instruments [Line Items]
Minimum percentage of fixed rate debt on total debt	70.00%
Impact on net annual finance expense due to a 1% change in interest rate	£ 130,000,000	£ 143,000,000	£ 108,000,000
Percentage of interest accrued	0.25%
Notional value of debt outstanding	£ 2,000,000,000
Expected change in financial expenses	10,000,000
Term debt	3,140,000,000	2,298,000,000	2,791,000,000		£ 2,298,000,000
Trade and other receivables	445,000,000	317,000,000	360,000,000		431,000,000
Trade and other receivables	3,238,000,000	4,029,000,000	3,860,000,000		£ 3,692,000,000
Currency Swap Contract and Interest Rate Swap [Member] | Credit Support Agreements [Member]
Disclosure of Nature and Extent of Risks Arising From Financial Instruments [Line Items]
Fair value notional amount	3,289,000,000
Net cash inflow from netting and credit support agreements	129,000,000		(220,000,000)	£ 100,000,000
Individually Insignificant Counterparties [Member]
Disclosure of Nature and Extent of Risks Arising From Financial Instruments [Line Items]
Cash collateral held	638,000,000	492,000,000	702,000,000
Non-Financial Assets [Member]
Disclosure of Nature and Extent of Risks Arising From Financial Instruments [Line Items]
Trade and other receivables	445,000,000	317,000,000	360,000,000
Prepayments and Other Receivables [Member]
Disclosure of Nature and Extent of Risks Arising From Financial Instruments [Line Items]
Trade and other receivables	1,456,000,000	1,496,000,000	1,106,000,000
Debt Maturing in September 2021 [Member]
Disclosure of Nature and Extent of Risks Arising From Financial Instruments [Line Items]
Undrawn committed borrowing facilities	£ 2,100,000,000	£ 2,100,000,000	£ 2,100,000,000
Debt maturity	Sep. 30, 2021
2019 [Member]
Disclosure of Nature and Extent of Risks Arising From Financial Instruments [Line Items]
Term debt	£ 1,200,000,000

Financial Instruments and Ris_4

Financial Instruments and Risk Management - Summary of Currency and Interest Rate Profile of Loans and Borrowings (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure of credit risk exposure [Line Items]
Ratio of fixed to floating	100.00%	100.00%	100.00%
Principal Repayment at Hedged Rates [Member]
Disclosure of credit risk exposure [Line Items]
Principal repayments of loans and borrowings at hedged rate	£ 17,970	£ 14,219	£ 12,138
Sterling [Member] | Principal Repayment at Hedged Rates [Member]
Disclosure of credit risk exposure [Line Items]
Principal repayments of loans and borrowings at hedged rate	17,381	13,710	11,497
Euros [Member] | Principal Repayment at Hedged Rates [Member]
Disclosure of credit risk exposure [Line Items]
Principal repayments of loans and borrowings at hedged rate	£ 589	£ 509	£ 641
Fixed Interest Rate [Member]
Disclosure of credit risk exposure [Line Items]
fixed interest rate – sterling	4.00%	4.40%	4.90%
Ratio of fixed to floating	75.00%	84.00%	79.00%
Fixed Interest Rate [Member] | Principal Repayment at Hedged Rates [Member]
Disclosure of credit risk exposure [Line Items]
Principal repayments of loans and borrowings at hedged rate	£ 13,556	£ 11,990	£ 9,633
Fixed Interest Rate [Member] | Sterling [Member] | Principal Repayment at Hedged Rates [Member]
Disclosure of credit risk exposure [Line Items]
Principal repayments of loans and borrowings at hedged rate	£ 13,556	£ 11,990	£ 9,633
Floating Interest Rate [Member]
Disclosure of credit risk exposure [Line Items]
Ratio of fixed to floating	25.00%	16.00%	21.00%
Floating Interest Rate [Member] | Principal Repayment at Hedged Rates [Member]
Disclosure of credit risk exposure [Line Items]
Principal repayments of loans and borrowings at hedged rate	£ 4,414	£ 2,229	£ 2,505
Floating Interest Rate [Member] | Sterling [Member] | Principal Repayment at Hedged Rates [Member]
Disclosure of credit risk exposure [Line Items]
Principal repayments of loans and borrowings at hedged rate	3,825	1,720	1,864
Floating Interest Rate [Member] | Euros [Member] | Principal Repayment at Hedged Rates [Member]
Disclosure of credit risk exposure [Line Items]
Principal repayments of loans and borrowings at hedged rate	£ 589	£ 509	£ 641

Financial Instruments and Ris_5

Financial Instruments and Risk Management - Summary of Impact on Equity, Before Tax, of a 1% Increase in Interest (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Sterling Interest Rates [Member]
Disclosure Of Foreign Currency Exchange Exposure [Line Items]
Impact on equity, before tax	£ 672	£ 628	£ 554
US Dollar Interest Rates [Member]
Disclosure Of Foreign Currency Exchange Exposure [Line Items]
Impact on equity, before tax	(350)	(267)	(348)
Euro Interest Rates [Member]
Disclosure Of Foreign Currency Exchange Exposure [Line Items]
Impact on equity, before tax	(399)	(401)	(229)
Sterling Strengthening [Member]
Disclosure Of Foreign Currency Exchange Exposure [Line Items]
Impact on equity, before tax	£ (219)	£ (236)	£ (269)

Financial Instruments and Ris_6

Financial Instruments and Risk Management - Summary of Credit Ratings (Detail)	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Moodys [Member]
Disclosure of external credit grades [Line Items]
Rating	Baa2	Baa2	Baa1
Outlook	Stable	Stable	Negative
Standard And Poor's [Member]
Disclosure of external credit grades [Line Items]
Rating	BBB	BBB+	BBB+
Outlook	Stable	Negative	Negative

Financial Instruments and Ris_7

Financial Instruments and Risk Management - Summary of Remaining Contractually-Agreed Cash Flows Including Interest Payable for Non-Derivative Financial Liabilities on Undiscounted Basis (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans and other borrowings	£ 18,720	£ 15,167	£ 13,707
Interest on loans and other borrowings	257	169	189
Trade and other payables	5,195	4,961	5,298
Provisions	231	300	292
Total	24,403	20,597	19,486
Gross Carrying Amount [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans and other borrowings	18,670	15,094	13,557
Interest on loans and other borrowings	7,001	5,316	4,683
Trade and other payables	5,195	4,961	5,298
Provisions	260	372	469
Total	31,126	25,743	24,007
Gross Carrying Amount [Member] | 2019 [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans and other borrowings	2,883	2,120	2,602
Interest on loans and other borrowings	584	468	532
Trade and other payables	5,195	4,961	5,298
Provisions	39	54	62
Total	8,701	7,603	8,494
Gross Carrying Amount [Member] | 2020 [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans and other borrowings	1,309	1,192	1,614
Interest on loans and other borrowings	528	421	415
Provisions	33	34	41
Total	1,870	1,647	2,070
Gross Carrying Amount [Member] | 2021 [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans and other borrowings	15	1,332	1,166
Interest on loans and other borrowings	520	381	364
Provisions	35	25	21
Total	570	1,738	1,551
Gross Carrying Amount [Member] | 2022 [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans and other borrowings	1,463	18	1,295
Interest on loans and other borrowings	519	374	327
Provisions	14	43	18
Total	1,996	435	1,640
Gross Carrying Amount [Member] | 2023 [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans and other borrowings	964	1,489	12
Interest on loans and other borrowings	505	372	319
Provisions	12	19	17
Total	1,481	1,880	348
Gross Carrying Amount [Member] | 2023 [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans and other borrowings	12,036	8,943	6,868
Interest on loans and other borrowings	4,345	3,300	2,726
Provisions	127	197	310
Total	16,508	12,440	9,904
Interest Payments Not Yet Accrued
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Interest on loans and other borrowings	(6,744)	(5,147)	(4,494)
Total	(6,744)	(5,147)	(4,494)
Fair Value Adjustments
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Loans and other borrowings	50	73	150
Total	50	73	150
Impact Of Discounting
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Provisions	(29)	(72)	(177)
Total	£ (29)	£ (72)	£ (177)

Financial Instruments and Ris_8

Financial Instruments and Risk Management - Summary of Remaining Contractually-Agreed Cash Flows Including Interest Payable for Non-Derivative Financial Liabilities on Undiscounted Basis (Detail) (Parenthetical) - GBP (£) £ in Millions	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Other payables	£ 1,479	£ 1,326	£ 1,298
Other Taxation and Social Security and Deferred Income [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Other payables	632	2,229	2,178
Non Financial Liabilities [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Other payables	£ 1,479	£ 1,326	£ 1,298

Financial Instruments and Ris_9

Financial Instruments and Risk Management - Summary of Contractually Agreed Cash Flows in Respect of Derivative Financial Instruments (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Derivatives-Analysed by Earliest Payment Date [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	£ 1,208	£ 1,210	£ 1,174
Derivatives-Analysed by Earliest Payment Date [Member] | Net Settled [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	839	1,026	1,126
Derivatives-Analysed by Earliest Payment Date [Member] | Gross Settled Inflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	(6,828)	(3,366)	(1,673)
Derivatives-Analysed by Earliest Payment Date [Member] | Gross Settled Outflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	7,197	3,550	1,721
Derivatives-Analysed by Earliest Payment Date [Member] | 2019 [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	224	180	297
Derivatives-Analysed by Earliest Payment Date [Member] | 2019 [Member] | Net Settled [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	167	140	291
Derivatives-Analysed by Earliest Payment Date [Member] | 2019 [Member] | Gross Settled Inflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	(950)	(547)	(576)
Derivatives-Analysed by Earliest Payment Date [Member] | 2019 [Member] | Gross Settled Outflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	1,007	587	582
Derivatives-Analysed by Earliest Payment Date [Member] | 2021 [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	166	152	198
Derivatives-Analysed by Earliest Payment Date [Member] | 2021 [Member] | Net Settled [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	131	156	198
Derivatives-Analysed by Earliest Payment Date [Member] | 2021 [Member] | Gross Settled Inflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	(96)	(446)
Derivatives-Analysed by Earliest Payment Date [Member] | 2021 [Member] | Gross Settled Outflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	131	442
Derivatives-Analysed by Earliest Payment Date [Member] | 2022 [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	205	166	114
Derivatives-Analysed by Earliest Payment Date [Member] | 2022 [Member] | Net Settled [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	163	143	114
Derivatives-Analysed by Earliest Payment Date [Member] | 2022 [Member] | Gross Settled Inflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	(591)	(29)
Derivatives-Analysed by Earliest Payment Date [Member] | 2022 [Member] | Gross Settled Outflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	633	52
Derivatives-Analysed by Earliest Payment Date [Member] | 2023 [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	260	184	104
Derivatives-Analysed by Earliest Payment Date [Member] | 2023 [Member] | Net Settled [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	207	161	104
Derivatives-Analysed by Earliest Payment Date [Member] | 2023 [Member] | Gross Settled Inflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	(1,042)	(29)
Derivatives-Analysed by Earliest Payment Date [Member] | 2023 [Member] | Gross Settled Outflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	1,095	52
Derivatives-Analysed by Earliest Payment Date [Member] | 2023 [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	173	376	123
Derivatives-Analysed by Earliest Payment Date [Member] | 2023 [Member] | Net Settled [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	43	291	123
Derivatives-Analysed by Earliest Payment Date [Member] | 2023 [Member] | Gross Settled Inflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	(3,660)	(2,149)
Derivatives-Analysed by Earliest Payment Date [Member] | 2023 [Member] | Gross Settled Outflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	3,790	2,234
Derivatives-Analysed by Earliest Payment Date [Member] | 2020 [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	180	152	338
Derivatives-Analysed by Earliest Payment Date [Member] | 2020 [Member] | Net Settled [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	128	135	296
Derivatives-Analysed by Earliest Payment Date [Member] | 2020 [Member] | Gross Settled Inflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	(489)	(166)	(1,097)
Derivatives-Analysed by Earliest Payment Date [Member] | 2020 [Member] | Gross Settled Outflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	541	183	1,139
Derivatives-Analysed Based on Holding Instrument to Maturity [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	1,208	1,210	1,174
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | Net Settled [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	839	1,026	1,126
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | Gross Settled Inflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	(6,828)	(3,366)	(1,673)
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | Gross Settled Outflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	7,197	3,550	1,721
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | 2019 [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	139	131	98
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | 2019 [Member] | Net Settled [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	82	91	92
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | 2019 [Member] | Gross Settled Inflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	(950)	(547)	(576)
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | 2019 [Member] | Gross Settled Outflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	1,007	587	582
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | 2021 [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	106	107	92
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | 2021 [Member] | Net Settled [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	71	85	92
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | 2021 [Member] | Gross Settled Inflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	(96)	(47)
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | 2021 [Member] | Gross Settled Outflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	131	69
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | 2022 [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	113	101	88
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | 2022 [Member] | Net Settled [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	71	80	88
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | 2022 [Member] | Gross Settled Inflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	(591)	(47)
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | 2022 [Member] | Gross Settled Outflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	633	68
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | 2023 [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	124	101	83
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | 2023 [Member] | Net Settled [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	71	80	83
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | 2023 [Member] | Gross Settled Inflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	(1,042)	(47)
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | 2023 [Member] | Gross Settled Outflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	1,095	68
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | 2023 [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	597	662	679
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | 2023 [Member] | Net Settled [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	467	599	679
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | 2023 [Member] | Gross Settled Inflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	(3,660)	(2,512)
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | 2023 [Member] | Gross Settled Outflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	3,790	2,575
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | 2020 [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	129	108	134
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | 2020 [Member] | Net Settled [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	77	91	92
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | 2020 [Member] | Gross Settled Inflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	(489)	(166)	(1,097)
Derivatives-Analysed Based on Holding Instrument to Maturity [Member] | 2020 [Member] | Gross Settled Outflows [Member]
Disclosure of maturity analysis for derivative financial liabilities [Line Items]
Derivative financial liabilities net settled	£ 541	£ 183	£ 1,139

Financial Instruments and Ri_10

Financial Instruments and Risk Management - Summary of Maximum Credit Risk Exposure of Financial Assets (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure of credit risk exposure [Line Items]
Maximum credit risk exposure	£ 23,645	£ 21,141	£ 18,872
Derivative Financial Assets [Member]
Disclosure of credit risk exposure [Line Items]
Maximum credit risk exposure	1,592	1,509	2,246
Investments [Member]
Disclosure of credit risk exposure [Line Items]
Maximum credit risk exposure	17,005	16,578	13,346
Trade and Other Receivables [Member]
Disclosure of credit risk exposure [Line Items]
Maximum credit risk exposure	1,782	2,533	2,754
Contract Assets [Member]
Disclosure of credit risk exposure [Line Items]
Maximum credit risk exposure	1,602
Cash and Cash Equivalent [Member]
Disclosure of credit risk exposure [Line Items]
Maximum credit risk exposure	£ 1,664	£ 521	£ 526

Financial Instruments and Ri_11

Financial Instruments and Risk Management - Summary of Credit Quality and Credit Concentration of Cash Equivalents, Current Asset Investments and Derivative Financial Assets (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure of external credit grades [Line Items]
Credit exposure	£ 5,977	£ 4,613	£ 3,825
Aa2/AA and Above [Member]
Disclosure of external credit grades [Line Items]
Credit exposure	2,522	2,575	1,444
Aa3/AA- [Member]
Disclosure of external credit grades [Line Items]
Credit exposure	1,376	313	208
A1/A+ [Member]
Disclosure of external credit grades [Line Items]
Credit exposure	1,145	651	952
A2/A [Member]
Disclosure of external credit grades [Line Items]
Credit exposure	649	628	370
A3/A [Member]
Disclosure of external credit grades [Line Items]
Credit exposure	50	180	204
Baa1/BBB+ [Member]
Disclosure of external credit grades [Line Items]
Credit exposure	75	59	561
Baa2/BBB and Below [Member]
Disclosure of external credit grades [Line Items]
Credit exposure	£ 160	£ 207	£ 86

Financial Instruments and Ri_12

Financial Instruments and Risk Management - Summary of Offsetting of Financial Assets and Liabilities (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Offsetting Of Financial Assets Liabilities [Abstract]
Amounts presented in the balance sheet, derivative financial liabilities	£ (940)	£ (837)	£ (903)
Rights of set off with derivative counterparties, derivative financial liabilities	802	754	693
Cash collateral, derivative financial liabilities	90	60	64
Net amount, derivative financial liabilities	(48)	(23)	(146)
Amounts presented in the balance sheet	652	672	1,343
Right of set off with derivative counterparties	0	0	0
Cash collateral	(548)	(432)	(638)
Net amount	104	240	705
Amounts presented in the balance sheet, derivative financial assets	1,592	1,509	2,246
Right of set off with derivative counterparties,derivative financial assets	(802)	(754)	(693)
Cash collateral, derivative financial assets	(638)	(492)	(702)
Net amount, derivative financial assets	£ 152	£ 263	£ 851

Financial Instruments and Ri_13

Financial Instruments and Risk Management - Summary of Derivative Financial Instruments are Held at Fair Value on Balance Sheet (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Derivative Financial Instruments [Line Items]
Current asset	£ 111	£ 197	£ 428
Non-current asset	1,481	1,312	1,818
Current liability	48	50	34
Non-current liability	892	787	869
Designated in a Cash Flow Hedge [Member]
Disclosure Of Derivative Financial Instruments [Line Items]
Current asset	102	187	417
Non-current asset	1,228	1,061	1,508
Current liability	40	41	25
Non-current liability	689	587	616
Other [Member]
Disclosure Of Derivative Financial Instruments [Line Items]
Current asset	9	10	11
Non-current asset	253	251	310
Current liability	8	9	9
Non-current liability	£ 203	£ 200	£ 253

Financial instruments and Ri_14

Financial instruments and Risk Management - Summary of Amounts Related to Items Designated as Hedging Instruments (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Detailed Information About Hedged Items [Line Items]
Amount recycled from cash flow hedge related reserves to P&L	£ 45	£ 34	£ (1)
Designated in a Cash Flow Hedge [Member] | Derivatives Designated As Hedging Instrument
Disclosure Of Detailed Information About Hedged Items [Line Items]
Notional principal	15,484	14,636	12,514
Asset	1,330	1,248	1,925
Liability	(729)	(628)	(641)
Balance in cash flow hedge related reserves (gain)/loss	(99)	59	(32)
Fair value (gain)/loss recognised in OCI	(176)	368	(884)
Amount recycled from cash flow hedge related reserves to P&L	18	(277)	938
Designated in a Cash Flow Hedge [Member] | Derivatives Designated As Hedging Instrument | Sterling, Euro And Us Dollar Denominated Borrowings [Member]
Disclosure Of Detailed Information About Hedged Items [Line Items]
Notional principal	13,518	12,504	10,041
Asset	1,311	1,222	1,845
Liability	(702)	(608)	(621)
Balance in cash flow hedge related reserves (gain)/loss	(48)	101	87
Fair value (gain)/loss recognised in OCI	(130)	347	(800)
Amount recycled from cash flow hedge related reserves to P&L	(19)	(333)	938
Designated in a Cash Flow Hedge [Member] | Derivatives Designated As Hedging Instrument | Us Dollar Step Up Interest on Us Denominated Borrowings [Member]
Disclosure Of Detailed Information About Hedged Items [Line Items]
Notional principal	145	143	146
Asset	3		5
Liability	(1)	(6)	(2)
Balance in cash flow hedge related reserves (gain)/loss	(38)	(29)	(45)
Fair value (gain)/loss recognised in OCI	(13)	13	(21)
Amount recycled from cash flow hedge related reserves to P&L	4	3	4
Designated in a Cash Flow Hedge [Member] | Derivatives Designated As Hedging Instrument | Foreign Currency Purchases, Principally Denominated in Us Dollar, Euro And Asia Pacific Currencies [Member]
Disclosure Of Detailed Information About Hedged Items [Line Items]
Notional principal	1,821	1,989	2,327
Asset	16	26	75
Liability	(26)	(14)	(18)
Balance in cash flow hedge related reserves (gain)/loss	(13)	(13)	(74)
Fair value (gain)/loss recognised in OCI	(33)	8	(63)
Amount recycled from cash flow hedge related reserves to P&L	33	53	(4)
Deferred Tax On Cash Flow Hedges | Derivatives Designated As Hedging Instrument
Disclosure Of Detailed Information About Hedged Items [Line Items]
Balance in cash flow hedge related reserves (gain)/loss	15	(22)	(95)
Derivatives Not In A Designated Hedge Relationship
Disclosure Of Detailed Information About Hedged Items [Line Items]
Asset	262	261	321
Liability	(211)	(209)	(262)
Cash Flow Hedges Net Of Deferred Tax And Derivatives Not In A Designated Hedge Relationship
Disclosure Of Detailed Information About Hedged Items [Line Items]
Asset	1,592	1,509	2,246
Liability	(940)	(837)	(903)
Balance in cash flow hedge related reserves (gain)/loss	£ (84)	£ 37	£ (127)

Financial instruments and Ri_15

Financial instruments and Risk Management - Summary of Amounts Related to Items Designated as Hedging Instruments (Parenthetical) (Detail) - Designated in a Cash Flow Hedge [Member]	12 Months Ended
	Mar. 31, 2019
Sterling, Euro And Us Dollar Denominated Borrowings [Member]
Disclosure Of Detailed Information About Hedged Items [Line Items]
Description of hedging instruments used to hedge risk exposures and how they are used	currency swaps and interest rate swaps
Us Dollar Step Up Interest on Us Denominated Borrowings [Member]
Disclosure Of Detailed Information About Hedged Items [Line Items]
Description of hedging instruments used to hedge risk exposures and how they are used	forward currency contracts
Foreign Currency Purchases, Principally Denominated in Us Dollar, Euro And Asia Pacific Currencies [Member]
Disclosure Of Detailed Information About Hedged Items [Line Items]
Description of hedging instruments used to hedge risk exposures and how they are used	forward currency contracts

Other Reserves - Summary of Oth

Other Reserves - Summary of Other Reserves (Detail) - GBP (£) £ in Millions		12 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Reserves Within Equity [Line Items]
Beginning balance		£ 22,347	£ 18,926	£ 21,325
Movements in relation to cash flow hedges recognised in income and expense		(45)	(34)	1
Tax recognised in other comprehensive income		(343)	262	(445)
Ending balance		21,788	22,347	18,926
Other Reserves [Member]
Disclosure Of Reserves Within Equity [Line Items]
Beginning balance		1,241	1,591	1,392
Exchange differences	[1]	64	(188)	227
Net fair value gain on cash flow hedges		176	(368)	884
Movements in relation to cash flow hedges recognised in income and expense		(18)	277	(938)
Fair value movement on available-for-sale assets		3	11	(3)
Tax recognised in other comprehensive income		(41)	1	29
Transfer to realised profit			(83)
Ending balance		1,425	1,241	1,591
At 31 March 2018			1,241
Other Reserves [Member] | Cash Flow Reserve [Member]
Disclosure Of Reserves Within Equity [Line Items]
Beginning balance	[2]	(37)	127	173
Net fair value gain on cash flow hedges	[2]	168	(368)	884
Movements in relation to cash flow hedges recognised in income and expense	[2]	(31)	277	(938)
Tax recognised in other comprehensive income	[2]	(37)	10	8
Transfer to realised profit	[2]		(83)
Ending balance	[2]	144	(37)	127
Transfer to cost of hedging reserve	[2]		81
At 31 March 2018	[2]		44
Other Reserves [Member] | Fair Value Reserve [Member]
Disclosure Of Reserves Within Equity [Line Items]
Beginning balance	[3]	24	13	16
Fair value movement on available-for-sale assets	[3]	3	11	(3)
Ending balance	[3]	27	24	13
At 31 March 2018	[3]		24
Other Reserves [Member] | Cost of Hedging Reserve [Member]
Disclosure Of Reserves Within Equity [Line Items]
Net fair value gain on cash flow hedges	[4]	8
Movements in relation to cash flow hedges recognised in income and expense	[4]	13
Ending balance	[4]	(60)
Transfer to cost of hedging reserve	[4]		(81)
At 31 March 2018	[4]		(81)
Other Reserves [Member] | Translation Reserve [Member]
Disclosure Of Reserves Within Equity [Line Items]
Beginning balance	[5]	396	593	345
Exchange differences	[1],[5]	64	(188)	227
Tax recognised in other comprehensive income	[5]	(4)	(9)	21
Ending balance	[5]	456	396	593
At 31 March 2018	[5]		396
Other Reserves [Member] | Merger and Other Reserves [Member]
Disclosure Of Reserves Within Equity [Line Items]
Beginning balance		858	858	858
Ending balance		£ 858	858	£ 858
At 31 March 2018			£ 858
[1]	Excludes £(2)m (2017/18: £1m, 2016/17: £10m) of exchange differences in relation to retained earnings attributed to non-controlling interests.
[2]	The cash flow reserve is used to record the effective portion of the cumulative net change in the fair value of cash flow hedging instruments related to hedged transactions that have not yet occurred. Amounts ‘recognised in income and expense’ include a net charge to the cash flow reserve of £30m (2017/18: credit of £295m, 2016/17: charge of £941m) relating to fair value movements on derivatives. The items generating these foreign exchange movements are in designated cash flow hedge relationships.
[3]	The fair value reserve (2018, 2017: available-for-sale reserve) is used to record the cumulative fair value gains and losses on assets classified as fair value through other comprehensive income (2018, 2017: available-for-sale financial assets). The cumulative gains and losses are recycled to the income statement on disposal of the asset
[4]	The cost of hedging reserve reflects the gain or loss on the portion excluded from the designated hedging instrument that relates to the currency basis element of our cross currency swaps. It is initially recognised in other comprehensive income and accounted for similarly to gains or losses in the cash flow reserve.
[5]	The translation reserve is used to record cumulative translation differences on the assets and liabilities of foreign operations. The cumulative translation differences are recycled to the income statement on disposal of the foreign operation.

Other Reserves - Summary of O_2

Other Reserves - Summary of Other Reserves (Parenthetical) (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Other Reserves [Member] | Cash Flow Reserve [Member]
Disclosure Of Reserves Within Equity [Line Items]
Net charge to cash flow reserve relating to fair value movements on derivatives	£ (30)	£ 295	£ (941)
Non-controlling interests [member]
Disclosure Of Reserves Within Equity [Line Items]
Exchange differences in relation to retained earnings attributed to non-controlling interests	£ (2)	£ 1	£ 10

Directors' Emoluments and Pensi

Directors' Emoluments and Pensions - Additional Information (Detail)	12 Months Ended
	Mar. 31, 2019GBP (£)£ / sharesshares	Mar. 31, 2018GBP (£)
Disclosure of defined benefit plans [Line Items]
Deferred bonuses payable to directors	£ 451,000	£ 319,000
Aggregate emoluments excluding deferred bonus	£ 2,973,000	£ 2,525,000
Number of directors with accrued retirement benefits under a money purchase scheme	0	0
Aggregate emoluments excluding deferred bonus	£ 1,606,000	£ 1,538,000
Deferred bonuses payable to directors	£ 327,000	£ 302,400
BT Group Share Options Plan [Member]
Disclosure of defined benefit plans [Line Items]
Number of director exercise options	0	0
BT Long Term Incentive Plans [Member]
Disclosure of defined benefit plans [Line Items]
Number of director exercise options	5	6
Number of options vested	£ 35,000	£ 179,000
Number of shares entitled to receive highest paid director | shares	3,148,023
Ordinary shares nominal value | £ / shares	£ 0.05

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2017	Mar. 31, 2016	May 24, 2019	Mar. 31, 2018	Mar. 31, 2002
Disclosure Of Transactions Between Related Parties [Line Items]
Dividends paid	£ 2,500	£ 2,350
Loan facility [Member]
Disclosure Of Transactions Between Related Parties [Line Items]
Applicable margin to LIBOR	1.025%
British Telecommunications plc [Member]
Disclosure Of Transactions Between Related Parties [Line Items]
Investment in the company						£ 18,500
Dividends paid	£ 2,500	£ 2,350
Final dividend declared					£ 2,500
British Telecommunications plc [Member] | Loan facility [Member] | Top of Range [Member]
Disclosure Of Transactions Between Related Parties [Line Items]
Undrawn committed borrowing facilities	35,000
British Telecommunications plc [Member] | Events After Reporting Period [Member]
Disclosure Of Transactions Between Related Parties [Line Items]
Final dividend declared	1,575			£ 1,575
Ultimate Parent Company [Member]
Disclosure Of Transactions Between Related Parties [Line Items]
Equity placing			£ 1,000
Ultimate Parent Company [Member] | Loan facility [Member] | Top of Range [Member]
Disclosure Of Transactions Between Related Parties [Line Items]
Undrawn committed borrowing facilities	£ 10,000

Related Party Transactions - Ba

Related Party Transactions - Balances with Parent and Ultimate Parent Companies and Finance Income or Expense (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017	Apr. 01, 2018
Disclosure Of Transactions Between Related Parties [Line Items]
Non-current assets investments	£ 13,519	£ 13,354	£ 11,606
Non-current liabilities loans	(15,837)	(13,038)	(11,105)	£ (13,038)
Trade and other receivables	16	15	25
Current asset investments	3,486	3,224	1,740
Current liabilities loans	(3,140)	(2,298)	(2,791)	£ (2,298)
Finance income	306	215	232
Finance (expense)	(833)	(794)	(842)
British Telecommunications plc [Member]
Disclosure Of Transactions Between Related Parties [Line Items]
Non-current assets investments	10,436	10,318	10,191
Non-current liabilities loans	(17,613)	(14,916)
Current asset investments	211	168	192
Trade and other payables	(55)	(50)	(63)
Current liabilities loans	(14,854)	(18,494)
Finance income	211	169	191
Ultimate Parent Company [Member]
Disclosure Of Transactions Between Related Parties [Line Items]
Non-current assets investments	3,029	2,983	1,371
Non-current liabilities loans	(1,061)	(1,044)	(1,024)
Trade and other receivables	16	15	25
Current asset investments	61	34	28
Trade and other payables	(1)
Current liabilities loans	(1,040)	(18)	(159)
Finance income	61	34	28
Finance (expense)	£ (43)	£ (18)	£ (25)

Related Party Transactions - _2

Related Party Transactions - Balances with Parent and Ultimate Parent Companies and Finance Income or Expense (Parenthetical) (Detail) - GBP (£) £ in Millions		12 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Transactions Between Related Parties [Abstract]
Net cash outflow on non-current amounts owed by ultimate parent company		£ 1,514
Cash inflow on non-current amounts owed from ultimate parent company		6
Cash outflow on non-current amounts owed by ultimate parent company	[1]	1,508	£ 1,677	£ 1,571
Non cash movements on non current asset investments		£ 41
[1]	There are non-cash movements in this intra-group loan arrangement which principally relate to the settlement of dividends with the parent company and amounts the ultimate parent company was owed by the parent company which were settled through their loan accounts with British Telecommunications plc. Refer to note 28 for further information.

Financial Commitments and Con_3

Financial Commitments and Contingent Liabilities - Disclosure of Financial Commitments (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Mar. 31, 2018
Financial Commitments [Abstract]
Operating lease commitments	£ 6,619	£ 6,597
TV programme rights commitments	2,113	2,823
Capital commitments	1,432	993
Other commitments	253	624
Total	£ 10,417	£ 11,037

Financial Commitments and Con_4

Financial Commitments and Contingent Liabilities - Disclosure of Future Minimum Operating Lease Payments (Detail) - GBP (£) £ in Millions	Mar. 31, 2019	Mar. 31, 2018
Disclosure Of Operating Leases Future Minimum Payments [Line Items]
Operating lease commitments	£ 6,619	£ 6,597
2019 [Member]
Disclosure Of Operating Leases Future Minimum Payments [Line Items]
Operating lease commitments		600
2020 [Member]
Disclosure Of Operating Leases Future Minimum Payments [Line Items]
Operating lease commitments	755	550
2021 [Member]
Disclosure Of Operating Leases Future Minimum Payments [Line Items]
Operating lease commitments	641	513
2022 [Member]
Disclosure Of Operating Leases Future Minimum Payments [Line Items]
Operating lease commitments	599	486
2023 [Member]
Disclosure Of Operating Leases Future Minimum Payments [Line Items]
Operating lease commitments	555	463
2024 [Member]
Disclosure Of Operating Leases Future Minimum Payments [Line Items]
Operating lease commitments	512	449
Thereafter [Member]
Disclosure Of Operating Leases Future Minimum Payments [Line Items]
Operating lease commitments	£ 3,557	£ 3,536

Financial Commitments and Con_5

Financial Commitments and Contingent Liabilities - Additional Information (Detail) - GBP (£) £ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disclosure of Financial Commitments [Line Items]
Average lease term	13 years	14 years
Average fixed rental term	13 years	14 years
Brazilian Tax Authority [Member]
Disclosure of Financial Commitments [Line Items]
value of claim	£ 204
Overall liability	£ 19

Post Balance Sheet Events - Add

Post Balance Sheet Events - Additional Information (Detail) £ in Millions	May 21, 2019GBP (£)
Court of Appeal [Member]
Disclosure Of Nonadjusting Events After Reporting Period [Line Items]
Payment of annual fee	£ 87