Santander UK (SANS+) 6-K 15 Aug 22 2022 Q2 Current report (foreign) Financial data

Cover Page

Cover Page	6 Months Ended
	Jun. 30, 2022
Cover [Abstract]
Document Type	6-K
Amendment Flag	false
Document Period End Date	Jun. 30, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q2
Entity Registrant Name	SANTANDER UK PLC
Entity Central Index Key	0001087711
Current Fiscal Year End Date	--12-31

Consolidated Income Statement U

Consolidated Income Statement Unaudited - GBP (£) £ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Profit (loss) [abstract]
Interest and similar income	£ 2,743	£ 2,355
Interest expense and similar charges	(623)	(450)
Net interest income	2,120	1,905
Fee and commission income	377	305
Fee and commission expense	(209)	(154)
Net fee and commission income	168	151
Other operating income	102	135
Total operating income	2,390	2,191
Operating expenses before credit impairment (losses)/write-backs, provisions and charges	(1,172)	(1,328)
Credit impairment (losses)/write-backs	(118)	70
Provisions for other liabilities and charges	(118)	(190)
Total operating credit impairment (losses)/write-backs, provisions and charges	(236)	(120)
Profit from continuing operations before tax	982	743
Tax on profit from continuing operations	(232)	(205)
Profit from continuing operations after tax	750	538
Profit from discontinued operations after tax	0	24
Profit after tax	750	562
Attributable to:
Equity holders of the parent	750	545
Non-controlling interests	0	17
Profit after tax	£ 750	£ 562

Consolidated Statement of Compr

Consolidated Statement of Comprehensive Income Unaudited - GBP (£) £ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Statement of comprehensive income [abstract]
Profit after tax	£ 750	£ 562
Movement in fair value reserve (debt instruments):
Change in fair value	(171)	(62)
Income statement transfers	162	59
Taxation	4	(1)
Other comprehensive income, fair value reserve (debt instruments)	(5)	(4)
Cash flow hedges:
Effective portion of changes in fair value	726	(618)
Income statement transfers	(1,807)	377
Taxation	299	41
Other comprehensive income, cash flow hedges, total	(782)	(200)
Net other comprehensive expense that may be reclassified to profit or loss subsequently	(787)	(204)
Pension remeasurement:
Change in fair value	326	745
Taxation	(26)	(248)
Pension remeasurement, total	300	497
Own credit adjustment:
Change in fair value	29	0
Taxation	(9)	0
Own credit adjustment, total	20	0
Net other comprehensive income that will not be reclassified to profit or loss subsequently	320	497
Total other comprehensive income/(expense) net of tax	(467)	293
Total comprehensive income	283	855
Attributable to:
Equity holders of the parent	283	837
Non-controlling interests	0	18
Total comprehensive income	£ 283	£ 855

Consolidated Balance Sheet Unau

Consolidated Balance Sheet Unaudited - GBP (£) £ in Millions	Jun. 30, 2022	Dec. 31, 2021
Assets
Cash and balances at central banks	£ 43,390	£ 48,139
Financial assets at fair value through profit or loss:
Derivative financial instruments	2,271	1,681
Other financial assets at fair value through profit or loss	155	185
Financial assets at amortised cost:
Loans and advances to customers	217,012	210,094
Loans and advances to banks	793	1,169
Repurchase agreements – non trading	8,793	12,683
Other financial assets at amortised cost	156	506
Financial assets at fair value through other comprehensive income	4,913	5,851
Interests in other entities	234	201
Intangible assets	1,538	1,545
Property, plant and equipment	1,490	1,548
Current tax assets	430	347
Retirement benefit assets	2,011	1,572
Other assets	1,082	1,577
Assets held for sale	49	0
Total assets	284,317	287,098
Financial liabilities at fair value through profit or loss:
Derivative financial instruments	720	777
Other financial liabilities at fair value through profit or loss	827	803
Financial liabilities at amortised cost:
Deposits by customers	189,729	192,926
Deposits by banks	35,182	33,855
Repurchase agreements – non trading	6,910	11,718
Debt securities in issue	29,521	25,520
Subordinated liabilities	2,335	2,228
Other liabilities	2,636	2,189
Provisions	363	364
Deferred tax liabilities	392	579
Retirement benefit obligations	29	37
Total liabilities	268,644	270,996
Equity
Share capital	3,105	3,105
Share premium	5,620	5,620
Other equity instruments	1,956	2,191
Retained earnings	5,646	5,053
Other reserves	(654)	133
Total shareholders’ equity	15,673	16,102
Total equity	15,673	16,102
Total liabilities and equity	£ 284,317	£ 287,098

Consolidated Cash Flow Statemen

Consolidated Cash Flow Statement Unaudited - GBP (£) £ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Cash flows from operating activities
Profit after tax	£ 982	£ 776
Adjustments for:
Non-cash items included in profit	827	431
Change in operating assets	(4,126)	5,450
Change in operating liabilities	(7,263)	(29)
Corporation taxes paid	(223)	(153)
Effects of exchange rate differences	878	(534)
Net cash flows from operating activities	(8,925)	5,941
Cash flows from investing activities
Purchase of property, plant and equipment and intangible assets	(263)	(350)
Proceeds from sale of property, plant and equipment and intangible assets	103	272
Purchase of financial assets at amortised cost and financial assets at FVOCI	(1,146)	(1,016)
Proceeds from sale and redemption of financial assets at amortised cost and financial assets at FVOCI	2,421	3,789
Net cash flows from investing activities	1,115	2,695
Cash flows from financing activities
Issue of other equity instruments	750	210
Issue of debt securities and subordinated notes	4,116	36
Issuance costs of debt securities and subordinated notes	(8)	(3)
Repayment of debt securities and subordinated notes	(1,977)	(8,031)
Repurchase of other equity instruments	(985)	(210)
Dividends paid on ordinary shares	(389)	0
Dividends paid on preference shares and other equity instruments	88	83
Principal elements of lease payments	(33)	(13)
Net cash flows from financing activities	1,386	(8,094)
Change in cash and cash equivalents	(6,424)	542
Cash and cash equivalents at beginning of the period	49,254	46,696
Effects of exchange rate changes on cash and cash equivalents	37	(10)
Cash and cash equivalents at the end of the period	42,867	47,228
Cash and cash equivalents consist of:
Cash and balances at central banks	43,390	39,021
Less: restricted balances	(2,137)	(1,677)
Cash and bank balances at central banks less regulatory minimum cash balances	41,253	37,344
Other cash equivalents: Loans and advances to banks - Non trading	733	1,437
Other cash equivalents: Reverse repurchase agreements	881	8,447
Cash and cash equivalents at the end of the period	£ 42,867	£ 47,228

Consolidated Statement of Chang

Consolidated Statement of Changes in Equity Unaudited - GBP (£) £ in Millions	Total	Total	Share capital	Share premium	Other equity instruments	Fair value	Cash flow hedging	Currency translation	Retained earnings	Non-controlling interests
Beginning balance at Dec. 31, 2020	£ 15,936	£ 15,774	£ 3,105	£ 5,620	£ 2,191	£ 28	£ 481	£ 1	£ 4,348	£ 162
Profit for the year	562	545							545	17
Other comprehensive (expense)/income, net of tax:
– Fair value reserve (debt instruments)	(4)	(4)				(4)
– Cash flow hedges	(200)	(200)					(200)
– Pension remeasurement	497	496							496	1
– Own credit adjustment	0
Total comprehensive income	855	837				(4)	(200)	0	1,041	18
Issue of other equity instruments	210	210			210
Repurchase of other equity instruments	(210)	(210)			(210)
Dividends on preference shares and other equity instruments	(83)	(83)							(83)
Ending balance at Jun. 30, 2021	16,708	16,528	3,105	5,620	2,191	24	281	1	5,306	180
Beginning balance at Dec. 31, 2021	16,102	16,102	3,105	5,620	2,191	25	107	1	5,053	0
Profit for the year	750	750							750
Other comprehensive (expense)/income, net of tax:
– Fair value reserve (debt instruments)	(5)	(5)				(5)
– Cash flow hedges	(782)	(782)					(782)
– Pension remeasurement	300	300							300
– Own credit adjustment	20	20							20
Total comprehensive income	283	283				(5)	(782)	0	1,070	0
Issue of other equity instruments	750	750			750
Repurchase of other equity instruments	(985)	(985)			(985)
Dividends on ordinary shares	(389)	(389)							(389)
Dividends on preference shares and other equity instruments	(88)	(88)							(88)
Ending balance at Jun. 30, 2022	£ 15,673	£ 15,673	£ 3,105	£ 5,620	£ 1,956	£ 20	£ (675)	£ 1	£ 5,646	£ 0

Accounting Policies

Accounting Policies	6 Months Ended
	Jun. 30, 2022
Disclosure Of Significant Accounting Policies [Abstract]
Accounting Policies	1. ACCOUNTING POLICIES The financial information in these Condensed Consolidated Interim Financial Statements is unaudited and does not constitute statutory accounts as defined in section 434 of the UK Companies Act 2006. These Condensed Consolidated Interim Financial Statements were approved by the Board of Directors on 11 August 2022. Statutory accounts for the year ended 31 December 2021 have been delivered to the Registrar of Companies. The Condensed Consolidated Interim Financial Statements reflect all adjustments that, in the opinion of management, are necessary for a fair statement of the results of operations for the interim period. All such adjustments to the financial information are of a normal, recurring nature. Because the results from common banking activities are so closely related and responsive to changes in market conditions, the results for any interim period are not necessarily indicative of the results that can be expected for the year. The Condensed Consolidated Interim Financial Statements have been prepared in accordance with International Accounting Standard IAS 34 ‘Interim Financial Reporting', as issued by the International Accounting Standards Board (IASB) and adopted in the UK, and the Disclosure Guidance and Transparency Rules sourcebook of the UK's Financial Conduct Authority (FCA). They do not include all the information and disclosures normally required for full annual financial statements and should be read in conjunction with the Consolidated Financial Statements of Santander UK plc (the Company) and its subsidiaries (collectively Santander UK or the Santander UK group) for the year ended 31 December 2021 which were prepared in accordance with UK-adopted International Accounting Standards (IAS). Those consolidated financial statements were also prepared in accordance with IFRSs as issued by the IASB, including interpretations issued by the IFRS Interpretations Committee, as there were no applicable differences from IFRSs as issued by the IASB for the periods presented. Except as noted below, the same accounting policies, presentation and methods of computation are followed in these Condensed Consolidated Interim Financial Statements as were applied in the presentation of Santander UK’s 2021 Annual Report. Property, plant and equipment During H122, Santander UK expanded its accounting policy for 'Property, plant and equipment' to separately address properties which it no longer occupies, and to identify such properties as ‘Investment property’. This change had no financial impact on these Condensed Consolidated Interim Financial Statements. Property that is held for long-term rental yields or for capital appreciation or both, and that is not occupied by the companies in the Santander UK group, is classified as investment property and included in property, plant and equipment. Investment property is accounted for in the same manner as owner-occupied property. In addition, rental income from investment property is recognised as other revenue on a straight-line basis over the term of the lease. Lease incentives granted are recognised as an integral part of the total rental income, over the term of the lease. Cash and cash equivalents Following a decision by the IFRS Interpretations Committee in April 2022, Santander UK updated its accounting policy to exclude from cash and cash equivalents Reserves Collateralisation Accounts (RCAs) balances held at the BoE relating to Santander UK’s participation in certain payments schemes. Instead, RCAs balances are classified as restricted balances and included within 'change in operating assets' in the cash flow statement. Prior periods have been restated. For the purposes of the cash flow statement, cash and cash equivalents comprise balances with less than three months maturity from the date of acquisition, including cash and non-restricted balances with central banks, treasury bills and other eligible bills, loans and advances to banks and short-term investments in securities. Balances with central banks represent amounts held at the BoE as part of the Santander UK group’s liquidity management activities. It includes certain minimum cash ratio deposits held for regulatory purposes and reserves collateralised accounts in respect of Santander UK’s participation in certain payments schemes which are required to be maintained with the BoE and are restricted balances. Non-current assets held for sale Non-current assets (or disposal groups) are classified as held for sale when their carrying amount is to be recovered principally through a sale transaction rather than continuing use. In order to be classified as held for sale, the asset must be available for immediate sale in its present condition subject only to terms that are usual and customary, and the sale must be highly probable. Non-current assets (or disposal groups) held for sale are measured at the lower of carrying amount and fair value less cost to sell, with the exception of financial instruments which remain governed by the requirements of IFRS 9 and are held at their IFRS 9 carrying value. Future accounting developments Disclosure of Accounting Policies – Amendments to IAS 1 and IFRS Practice Statement 2 In February 2021, the IASB amended IAS 1 Presentation of Financial Statements to require entities to disclose their material rather than their significant accounting policies. To support this amendment, the IASB also amended IFRS Practice Statement 2 Making Materiality Judgements to provide guidance on how to apply the concept of materiality. The amendments are effective for annual periods beginning on or after 1 January 2023 with earlier application permitted. The amendments are awaiting UK endorsement. The amendments are expected to streamline and improve our accounting policy disclosures by making them more specific to the Santander UK group. Going concern In light of the continuing economic uncertainty, the Directors updated their going concern assessment in preparing these Condensed Consolidated Interim Financial Statements. After making enquiries, the Directors have a reasonable expectation that Santander UK has adequate resources to continue in operational existence for at least twelve months from the date of this report and, therefore, having reassessed the principal risks and uncertainties, the Directors consider it appropriate for the Condensed Consolidated Interim Financial Statements to be prepared on a going concern basis. In making their going concern assessment in connection with preparing the Condensed Consolidated Interim Financial Statements, the Directors considered a wide range of information that included Santander UK’s long-term business and strategic plans, forecasts and projections, estimated capital, funding and liquidity requirements, contingent liabilities and the reasonably possible changes in trading performance arising from potential economic, market and product developments. CRITICAL JUDGEMENTS AND ACCOUNTING ESTIMATES The preparation of the Condensed Consolidated Interim Financial Statements requires management to make judgements and accounting estimates that affect the reported amount of assets and liabilities at the reporting date and the reported amount of income and expenses during the reporting period. Management evaluates its judgements and accounting estimates, which are based on historical experience and on various other factors that are believed to be reasonable under the circumstances, on an ongoing basis. Actual results may differ from these accounting estimates under different assumptions or conditions. In preparing the Condensed Consolidated Interim Financial Statements, no significant judgements were made in applying the accounting policies, other than those involving estimations about credit impairment losses, provisions and contingent liabilities, pensions and goodwill. There has been no change in the inherent sensitivity of the areas of judgement in the period. Management have considered the impact of developments in principal risks and uncertainties, as set out in the Risk review, on critical judgements and accounting estimates. a) Credit impairment losses Key judgements – Determining an appropriate definition of default – Establishing the criteria for a significant increase in credit risk (SICR) and, for corporate borrowers, internal credit risk rating – Determining appropriate post model adjustments – Assessing individual corporate Stage 3 exposures Key estimates – Forward-looking multiple economic scenario assumptions – Probability weights assigned to multiple economic scenarios For more on each of these key judgements and estimates, see 'Critical judgements and accounting estimates applied in calculating ECL' in the ‘Credit risk – credit risk management’ section of the Risk review in the 2021 Annual Report. Sensitivity of ECL allowance For detailed disclosures, see 'Sensitivity of ECL allowance' in the ‘Credit risk – credit risk management’ section of the Risk review. b) Provisions and contingent liabilities Key judgements – Determining whether a present obligation exists – Assessing the likely outcome of future legal decisions Key estimates – Probability, timing, nature and amount of any outflows that may arise from past events Included in Litigation and other regulatory provisions in Note 24 are amounts in respect of management’s best estimates of liability relating to a legal dispute regarding allocation of responsibility for a specific PPI portfolio of complaints, and Plevin related litigation. Note 26 provides disclosure relating to ongoing factual issues and reviews that could impact the timing and amount of any outflows. Note 26 includes disclosure relating to an investigation in relation to the historical involvement of Santander UK plc, Santander Financial Services plc and Cater Allen International Limited (all subsidiaries of Santander UK Group Holdings plc) in German dividend tax arbitrage transactions, as well as an FCA civil regulatory investigation which commenced in July 2017 into our compliance with the Money Laundering Regulations 2007 and potential breaches of FCA principles and rules relating to anti-money laundering and financial crime systems and controls. These judgements are based on the specific facts available and often require specialist professional advice. There can be a wide range of possible outcomes and uncertainties, particularly in relation to legal actions, and regulatory and consumer credit matters. As a result, it is often not possible to make reliable estimates of the likelihood and amount of any potential outflows, or to calculate any resulting sensitivities. For more on these key judgements and estimates, see Notes 24 and 26. c) Pensions Key judgements – Setting the criteria for constructing the corporate bond yield curve used to determine the discount rate – Determining the methodology for setting the inflation assumption Key estimates – Discount rate applied to future cash flows – Rate of price inflation – Expected lifetime of the schemes' members – Valuation of pension fund assets whose values are not based on market observable data For more on each of these key judgements and estimates, see Note 25. Sensitivity of defined benefit pension scheme estimates For detailed disclosures, see ‘Actuarial assumption sensitivities’ in Note 25. The Scheme was invested in certain assets whose values are not based on market observable data, such as investments in private equity funds and property. Due diligence has been conducted to ensure the values obtained in respect of these assets are appropriate and represent fair value. Given the nature of these investments, we are unable to prepare sensitivities on how their values could vary as market conditions or other variables change. d) Goodwill Key judgements: – Determining the basis of goodwill impairment calculation assumptions, including management's planning assumptions considering internal capital allocations needed to support Santander UK's strategy, current market conditions and the macro-economic outlook. Key estimates: – Forecast cash flows for cash generating units, including estimated allocations of regulatory capital – Growth rate beyond initial cash flow projections – Discount rates which factor in risk-free rates and applicable risk premiums All of these variables are subject to fluctuations in external market rates and economic conditions beyond management’s control For more on each of these key judgements and estimates, see Note 16. Sensitivity of goodwill

Segments

Segments	6 Months Ended
	Jun. 30, 2022
Disclosure of operating segments [abstract]
Segments	2. SEGMENTS Santander UK’s principal activity is financial services, mainly in the UK. The business is managed and reported on the basis of four segments, which are strategic business units that offer different products and services, have different customers and require different technology and marketing strategies. As reflected in the 2021 Annual Report, the segmental basis of presentation in these Condensed Consolidated Interim Financial Statements changed following a management review of our structure in Q4 2021. Previously, Consumer Finance was managed as part of Retail Banking. Santander UK plc transferred a significant part of its Corporate & Investment Banking business to the London branch of Banco Santander SA under a Part VII banking business transfer scheme, which completed on 11 October 2021. The residual parts of the Corporate & Investment Banking business have been wound down or transferred to other segments. For the periods prior to its sale, the Corporate & Investment Banking business met the requirements for presentation as discontinued operations. For more details, see Note 33. Results by segment For the Half Year to Retail Banking Consumer Finance Corporate & Commercial Banking Corporate Centre Total 30 June 2022 £m £m £m £m £m Net interest income 1,784 92 242 2 2,120 Non-interest income 116 101 69 (16) 270 Total operating income 1,900 193 311 (14) 2,390 Operating expenses before credit impairment (losses)/write-backs, provisions and charges (831) (73) (181) (87) (1,172) Credit impairment (losses)/write-backs (126) (13) 19 2 (118) Provisions for other liabilities and charges (101) — (2) (15) (118) Total operating credit impairment (losses)/write-backs, provisions and charges (227) (13) 17 (13) (236) Profit/(loss) from continuing operations before tax 842 107 147 (114) 982 Revenue from external customers 2,033 243 318 (204) 2,390 Inter-segment revenue (133) (50) (7) 190 — Total operating income 1,900 193 311 (14) 2,390 Revenue from external customers includes the following fee and commission income disaggregated by income type: (1) – Current account and debit card fees 218 — 29 — 247 – Insurance, protection and investments 31 — — — 31 – Credit cards 46 — — — 46 – Non-banking and other fees (2) 4 8 36 5 53 Total fee and commission income 299 8 65 5 377 Fee and commission expense (191) — (11) (7) (209) Net fee and commission income/(expense) 108 8 54 (2) 168 Customer loans 189,318 5,129 17,358 1,711 213,516 Total assets (3) 196,505 9,652 17,358 60,802 284,317 Of which assets held for sale — — — 49 49 Customer deposits 154,759 — 25,305 3,940 184,004 Total liabilities 155,199 1,153 25,326 86,966 268,644 (1) The disaggregation of fees and commission income as shown above is not included in reports provided to the chief operating decision maker but is provided to show the split by reportable segments. (2) Non-banking and other fees include mortgages (except mortgage account fees), consumer finance, commitment commission, asset finance, invoice finance and trade finance. (3) Includes customer loans, net of credit impairment loss allowances. Retail Banking (4) Consumer Finance (4) Corporate & Commercial Banking Corporate & Investment Banking Corporate Centre Total 30 June 2021 £m £m £m £m £m £m Net interest income/(expense) 1,602 135 202 — (34) 1,905 Non-interest income 109 77 51 — 49 286 Total operating income 1,711 212 253 — 15 2,191 Operating expenses before credit impairment (losses)/write-backs, provisions and charges (858) (90) (181) — (199) (1,328) Credit impairment (losses)/write-backs 28 20 23 — (1) 70 Provisions for other liabilities and charges (67) — (5) — (118) (190) Total operating credit impairment (losses)/write-backs, provisions and charges (39) 20 18 — (119) (120) Profit/(loss) from continuing operations before tax 814 142 90 — (303) 743 Revenue from external customers 1,939 255 272 — (275) 2,191 Inter-segment revenue (228) (43) (19) — 290 — Total operating income/(expense) 1,711 212 253 — 15 2,191 Revenue from external customers includes the following fee and commission income disaggregated by income type: (1) – Current account and debit card fees 172 — 23 — — 195 – Insurance, protection and investments 32 — — — — 32 – Credit cards 37 — — — — 37 – Non-banking and other fees (2) 1 4 29 — 7 41 Total fee and commission income 242 4 52 — 7 305 Fee and commission expense (136) — (10) — (8) (154) Net fee and commission income 106 4 42 — (1) 151 31 December 2021 Customer loans 183,023 4,984 16,997 — 2,284 207,288 Total assets (3) 190,629 8,873 16,997 — 70,599 287,098 Customer deposits 156,991 — 25,597 — 3,627 186,215 Total liabilities 157,622 1,173 25,613 — 86,588 270,996 (1) The disaggregation of fees and commission income as shown above is not included in reports provided to the chief operating decision maker but is provided to show the split by reportable segments. (2) Non-banking and other fees include mortgages (except mortgage account fees), consumer finance, commitment commission, asset finance, invoice finance and trade finance. (3) Includes customer loans, net of credit impairment loss allowances. (4) Restated to reflect the resegmentation of the Retail Banking segment into the Retail Banking and Consumer Finance segments described above, and a refinement of our fee and commission income disaggregation. Geographical information is not provided, as substantially all of Santander UK’s activities are in the UK.

Other Operating Income

Other Operating Income	6 Months Ended
	Jun. 30, 2022
Net Trading And Other Income [abstract]
Other Operating Income	3. OTHER OPERATING INCOME In H122, the Santander UK group repurchased certain debt securities and subordinated liabilities as part of ongoing liability management exercises, resulting in a loss of £1m. In H121, the Santander UK group repurchased certain debt securities as part of ongoing liability management exercises, resulting in a loss of £27m.

Operating Expenses Before Credi

Operating Expenses Before Credit Impairment Losses, Provisions and Charges	6 Months Ended
	Jun. 30, 2022
Expenses by nature [abstract]
Operating Expenses Before Credit Impairment Losses, Provisions and Charges	4. OPERATING EXPENSES BEFORE CREDIT IMPAIRMENT LOSSES, PROVISIONS AND CHARGES For the Half Year to 30 June 2022 30 June 2021 £m £m Staff costs 556 577 Other administration expenses 458 431 Depreciation, amortisation and impairment 158 320 1,172 1,328 In H122, 'Depreciation, amortisation and impairment' included an impairment charge of £10m ( H121 : £105m) associated with branch and head office site closures as part of the transformation programme. For more, see Note 17.

Credit Impairment Losses and Pr

Credit Impairment Losses and Provisions	6 Months Ended
	Jun. 30, 2022
Disclosure Of Credit Impairment Loss And Provisions [Abstract]
Credit Impairment Losses and Provisions	5. CREDIT IMPAIRMENT LOSSES AND PROVISIONS For the Half Year to 30 June 2022 30 June 2021 £m £m Credit impairment losses/(write-backs): Loans and advances to customers 114 (33) Recoveries of loans and advances, net of collection costs (6) (13) Off-balance sheet exposures (See Note 24) 10 (24) 118 (70) Provisions for other liabilities and charges (excluding off-balance sheet credit exposures) (See Note 24) 121 191 Releases for residual value and voluntary termination (3) (1) 118 190 236 120 In H122 and H121 there were no material credit impairment losses on loans and advances to banks, non-trading reverse repurchase agreements, other financial assets at amortised cost and financial assets at FVOCI.

Taxation

Taxation	6 Months Ended
	Jun. 30, 2022
Major components of tax expense (income) [abstract]
Taxation	6. TAXATION The Santander UK group’s effective tax rate for H122 was 23.6% (H121: 27.6%). The tax on profit from continuing operations before tax differs from the theoretical amount that would arise using the basic corporation tax rate as follows: For the Half Year to 30 June 2022 30 June 2021 £m £m Profit from continuing operations before tax 982 743 Tax calculated at a tax rate of 19% (H121: 19%) 187 141 Bank surcharge on profits 70 49 Non-deductible preference dividends paid 5 6 Non-deductible UK Bank Levy 8 14 Non-deductible conduct remediation, fines and penalties (1) — Other non-deductible costs and non-taxable income 8 14 Effect of change in tax rate on deferred tax provision (23) 13 Tax relief on dividends in respect of other equity instruments (22) (32) Tax on profit from continuing operations 232 205 Interim period corporation tax is accrued based on the estimated average annual effective corporation tax for the year of 26.0% (H121: 25.8% ) before including both the impact of the changes in the standard rate of corporation tax (substantively enacted in 2021) and the bank surcharge (substantively enacted in 2022). See Note 9 to the Consolidated Financial Statements in the 2021 Annual Report.

Dividends on Ordinary Shares

Dividends on Ordinary Shares	6 Months Ended
	Jun. 30, 2022
Dividends On Ordinary Shares [Abstract]
Dividends on Ordinary Shares	7. DIVIDENDS ON ORDINARY SHARES £389m int erim dividend was declared on the Company’s ordinary shares in issue (H121: £nil ).

Derivative Financial Instrument

Derivative Financial Instruments	6 Months Ended
	Jun. 30, 2022
Disclosure of nature and extent of risks arising from financial instruments [abstract]
Derivative Financial Instruments	8. DERIVATIVE FINANCIAL INSTRUMENTS 30 June 2022 31 December 2021 Fair value Fair value Notional amount Assets Liabilities Notional amount Assets Liabilities £m £m £m £m £m £m Derivatives held for trading: Exchange rate contracts 13,712 287 314 11,036 159 168 Interest rate contracts 29,363 404 602 25,148 463 485 Equity and credit contracts 1,005 141 35 1,056 161 54 Total derivatives held for trading 44,080 832 951 37,240 783 707 Derivatives held for hedging Designated as fair value hedges: Exchange rate contracts 490 20 2 590 39 — Interest rate contracts 83,070 1,377 447 80,514 904 737 83,560 1,397 449 81,104 943 737 Designated as cash flow hedges: Exchange rate contracts 24,636 1,602 111 22,239 996 338 Interest rate contracts 25,361 223 992 21,466 180 216 49,997 1,825 1,103 43,705 1,176 554 Total derivatives held for hedging 133,557 3,222 1,552 124,809 2,119 1,291 Derivative netting (1) (1,783) (1,783) (1,221) (1,221) Total derivatives 177,637 2,271 720 162,049 1,681 777 (1) Derivative netting excludes the effect of cash collateral, which is offset against the gross derivative position. The amount of cash collateral received that had been offset against the gross derivative assets was £557m ( 2021 : £189m ) and the amount of cash collateral paid that had been offset against the gross derivative liabilities was £557m ( 2021 : £202m ). IBOR Reform Note 32 includes details of the notional value of hedging instruments by benchmark interest rate impacted by IBOR reform and the notional amounts of assets, liabilities and off-balance sheet commitments affected by IBOR reform that have yet to transition to an alternative benchmark interest rate.

Other Financial Assets at Fair

Other Financial Assets at Fair Value Through Profit or Loss	6 Months Ended
	Jun. 30, 2022
Financial assets at fair value through profit or loss [abstract]
Other Financial Assets at Fair Value Through Profit or Loss	9. OTHER FINANCIAL ASSETS AT FAIR VALUE THROUGH PROFIT OR LOSS 30 June 2022 31 December 2021 £m £m Loans and advances to customers: Loans to housing associations 11 12 Other loans 49 62 60 74 Debt securities 95 111 155 185

Loans and Advances to Customers

Loans and Advances to Customers	6 Months Ended
	Jun. 30, 2022
Net Loans And Advances To Customers [Abstract]
Loans and Advances to Customers	10. LOANS AND ADVANCES TO CUSTOMERS 30 June 2022 31 December 2021 £m £m Loans and advances to customers 217,910 210,947 Credit impairment loss allowances on loans and advances to customers (876) (828) Residual value and voluntary termination provisions on finance leases (22) (25) Net loans and advances to customers 217,012 210,094 For movements in expected credit losses, see the 'Movement in total exposures and the corresponding ECL' table in the Santander UK group level - Credit risk review section of the Risk review.

Securitisations and Covered Bon

Securitisations and Covered Bonds	6 Months Ended
	Jun. 30, 2022
Disclosure Of Securitisations And Covered Bonds [Abstract]
Securitisations and Covered Bonds	11. SECURITISATIONS AND COVERED BONDS The information in this Note relates to securitisations and covered bonds for consolidated structured entities, used to obtain funding or collateral. It excludes structured entities relating to credit protection transactions. 30 June 2022 31 December 2021 £m £m Mortgage-backed master trust structures: – Holmes 2,010 2,294 – Fosse 1,910 2,154 3,920 4,448 Other asset-backed securitisation structures: – Motor 18 38 18 38 Total securitisation programmes 3,938 4,486 Covered bond programmes – Euro 35bn Global Covered Bond Programme 20,245 15,713 Total securitisation and covered bond programmes 24,183 20,199 The following table sets out the internal and external issuances and redemptions in H122 and H121 for each securitisation and covered bond programme. Internal issuances External issuances Internal redemptions External redemptions H122 H121 H122 H121 H122 H121 H122 H121 £bn £bn £bn £bn £bn £bn £bn £bn Mortgage-backed master trust structures: – Holmes — — — — — — — 0.3 – Langton — — — — — 2.4 — — Other asset-backed securitisation structures: – Motor — — — — — 0.1 — — – Auto ABS UK Loans — — — — — 0.1 — 0.1 Covered bond programme — — — — — — — 4.5 — — — — — 2.6 — 4.9 In H121, all the remaining Langton bonds were redeemed and all the remaining associated mortgages were repurchased by Santander UK plc. There was no gain or loss on redemption. Auto ABS UK Loans was held in PSA Finance UK Limited (PSA), which was a subsidiary of the Santander UK group. On 30 July 2021, the Santander UK group through Santander Consumer (UK) plc sold its entire 50% shareholding in PSA to PSA Financial Services Spain EFC SA, a joint venture between Santander Consumer Finance SA, a fellow subsidiary of Banco Santander SA, and Banque PSA Finance SA, the auto finance arm of Group PSA Peugeot Citroën.

Reverse Repurchase Agreements -

Reverse Repurchase Agreements - Non Trading	6 Months Ended
	Jun. 30, 2022
Disclosure Of Reserve Repurchase Agreements Non-Trading [Abstract]
Reverse Repurchase Agreements - Non Trading	12. REVERSE REPURCHASE AGREEMENTS – NON TRADING 30 June 2022 31 December 2021 £m £m Agreements with banks 475 447 Agreements with customers 8,318 12,236 8,793 12,683

Other Financial Assets at Amort

Other Financial Assets at Amortised Cost	6 Months Ended
	Jun. 30, 2022
Financial assets at fair value through profit or loss [abstract]
Other Financial Assets at Amortised Cost	13. OTHER FINANCIAL ASSETS AT AMORTISED COST 30 June 2022 31 December 2021 £m £m Asset backed securities 94 443 Debt securities 62 63 0 156 506

Financial Assets at Fair Value

Financial Assets at Fair Value Through Other Comprehensive Income	6 Months Ended
	Jun. 30, 2022
Financial assets at fair value through other comprehensive income [abstract]
Financial Assets at Fair Value Through Other Comprehensive Income	14. FINANCIAL ASSETS AT FAIR VALUE THROUGH OTHER COMPREHENSIVE INCOME 30 June 2022 31 December 2021 £m £m Debt securities 4,894 5,833 Loans and advances to customers 19 18 4,913 5,851

Interests in Other Entities

Interests in Other Entities	6 Months Ended
	Jun. 30, 2022
Investments accounted for using equity method [abstract]
Interests in Other Entities	15. INTERESTS IN OTHER ENTITIES There have been no significant changes to the Santander UK group's interests in subsidiaries, joint ventures and unconsolidated structured entities, as set out in Note 19 to the Consolidated Financial Statements in the 2021 Annual Report.

Intangible Assets

Intangible Assets	6 Months Ended
	Jun. 30, 2022
Disclosure of detailed information about intangible assets [abstract]
Intangible Assets	16. INTANGIBLE ASSETS At 30 June 2022, intangible assets comprised goodwill of £1,199m (2021: £1,203m) and computer software of £339m (2021: £342m).

Property, Plant and Equipment

Property, Plant and Equipment	6 Months Ended
	Jun. 30, 2022
Property, plant and equipment [abstract]
Property, Plant and Equipment	17. PROPERTY, PLANT AND EQUIPMENT Property Office fixtures and equipment Computer software Operating lease assets Right-of-use assets Total (1) £m £m £m £m £m £m Cost: At 1 January 2022 978 1,049 434 755 254 3,470 Additions 31 29 — 112 32 204 Reclassification to assets held for sale (109) (31) — — — (140) Disposals (25) (268) (363) (126) (23) (805) At 30 June 2022 875 779 71 741 263 2,729 Accumulated depreciation: At 1 January 2022 334 857 434 160 137 1,922 Charge for the period 10 34 — 41 9 94 Impairment during the period 8 2 — — — 10 Reclassification to assets held for sale (62) (29) — — — (91) Disposals (16) (265) (363) (51) (1) (696) At 30 June 2022 274 599 71 150 145 1,239 Net book value 601 180 — 591 118 1,490 (1) Property, plant and equipment includes assets under construction of £155m (2021: £106m) and investment properties of £20m (2021: £17m).

Other Financial Liabilities at

Other Financial Liabilities at Fair Value Through Profit or Loss	6 Months Ended
	Jun. 30, 2022
Disclosure of financial liabilities [abstract]
Other Financial Liabilities at Fair Value Through Profit or Loss	18. OTHER FINANCIAL LIABILITIES AT FAIR VALUE THROUGH PROFIT OR LOSS 30 June 2022 31 December 2021 £m £m US$30bn Euro Medium Term Note Programme 3 5 Structured Notes Programmes 353 413 Eurobonds 110 142 Structured deposits 346 223 Collateral and associated financial guarantees 15 20 827 803

Deposits by Customers

Deposits by Customers	6 Months Ended
	Jun. 30, 2022
Deposits from customers [abstract]
Deposits by Customers	19. DEPOSITS BY CUSTOMERS 30 June 2022 31 December 2021 £m £m Demand and time deposits (1) 183,553 185,843 Amounts due to other Santander UK Group Holdings plc subsidiaries 63 59 Amounts due to Santander UK Group Holdings plc (2) 4,987 5,874 Amounts due to fellow Banco Santander subsidiaries and joint ventures 1,126 1,150 189,729 192,926 (1) Includes equity index-linked deposits of £520m (2021: £549m). The capital amount guaranteed/protected and the amount of return guaranteed in respect of the equity index-linked deposits were £520m and £2m (2021: £549m and £2m) respectively. (2) Includes downstreamed funding from our immediate parent company Santander UK Group Holdings plc.

Deposits by Banks

Deposits by Banks	6 Months Ended
	Jun. 30, 2022
Disclosure Of Deposits From Banks [Abstract]
Deposits by Banks	20. DEPOSITS BY BANKS 30 June 2022 31 December 2021 £m £m Items in the course of transmission 447 414 Deposits held as collateral 1,627 931 Other deposits (1) 33,105 32,507 Amounts due to Santander UK subsidiaries 3 3 35,182 33,855 (1) Includes drawdown from the TFS of £0.0bn (2021:£0.0bn) and drawdown from the TFSME of £31.9bn (2021: £31.9bn).

Repurchase Agreements - Non Tra

Repurchase Agreements - Non Trading	6 Months Ended
	Jun. 30, 2022
Disclosure Of Repurchase Agreements [Abstract]
Repurchase Agreements - Non Trading	21. REPURCHASE AGREEMENTS – NON TRADING 30 June 2022 31 December 2021 £m £m Agreements with banks 2,558 4,145 Agreements with customers 4,352 7,573 6,910 11,718

Debt Securities in Issue

Debt Securities in Issue	6 Months Ended
	Jun. 30, 2022
Debt Securities In Issue [Abstract]
Debt Securities in Issue	22. DEBT SECURITIES IN ISSUE 30 June 2022 31 December 2021 £m £m Medium-term notes 7,972 6,851 Euro 35bn Global Covered Bond Programme 15,952 12,760 US$20bn Commercial Paper Programmes 3,434 2,704 Certificates of deposit 1,667 2,387 Credit linked notes 60 59 Securitisation programmes 436 759 29,521 25,520

Subordinated Liabilities

Subordinated Liabilities	6 Months Ended
	Jun. 30, 2022
Subordinated liabilities [abstract]
Subordinated Liabilities	23. SUBORDINATED LIABILITIES 30 June 2022 31 December 2021 £m £m 2,335 2,228

Provisions

Provisions	6 Months Ended
	Jun. 30, 2022
Disclosure of other provisions [abstract]
Provisions	24. PROVISIONS Customer remediation Litigation and other regulatory Bank Levy Property ECL on undrawn facilities and guarantees Restructuring Other Total £m £m £m £m £m £m £m £m At 1 January 2022 44 166 1 74 38 28 13 364 Additional provisions (See Note 5) 25 16 — 1 10 8 84 144 Provisions released (See Note 5) (12) (1) — — — — — (13) Utilisation and other (8) (15) (1) (11) (2) (12) (83) (132) At 30 June 2022 49 166 — 64 46 24 14 363 A £25m customer remediation provision was recognised in H122 relating to the proposed refund of certain charges historically paid by cohorts of mortgage customers. In H122, Other provisions included charges for operational risk provisions of £78m (H121: £50m), including fraud losses of £63m (H121: £37m).

Retirement Benefit Plans

Retirement Benefit Plans	6 Months Ended
	Jun. 30, 2022
Disclosure of net defined benefit liability (asset) [abstract]
Retirement Benefit Plans	25. RETIREMENT BENEFIT PLANS The amounts recognised in the balance sheet were as follows: 30 June 2022 31 December 2021 £m £m Assets/(liabilities) Funded defined benefit pension scheme - surplus 2,011 1,572 Unfunded pension and post-retirement medical benefits (29) (37) Total net assets 1,982 1,535 An expense of £30m (H121: £33m) was recognised for defined contribution plans in the period and is included in staff costs within operating expenses (see Note 4). b) Defined benefit pension schemes The total amount charged to the income statement was £4m (H121: £23m ). The amounts recognised in other comprehensive income were as follows: 30 June 2022 30 June 2021 £m £m Return on plan assets (excluding amounts included in net interest expense) 3,352 383 Actuarial gains arising from experience adjustments 296 (30) Actuarial gains arising from changes in financial assumptions (3,974) (1,098) Pension remeasurement (326) (745) The net assets recognised in the balance sheet were determined as follows: 30 June 2022 31 December 2021 £m £m Present value of defined benefit obligations (9,138) (12,878) Fair value of scheme assets 11,120 14,413 Net defined benefit assets 1,982 1,535 Actuarial assumptions The principal actuarial assumptions used for the defined benefit schemes were: 30 June 2022 31 December 2021 % % To determine benefit obligations (1) : – Discount rate for scheme liabilities 3.8 1.9 – General price inflation 3.1 3.4 – General salary increase 1.0 1.0 – Expected rate of pension increase 3.0 3.2 Years Years Longevity at 60 for current pensioners, on the valuation date: – Males 27.5 27.5 – Females 30.2 30.1 Longevity at 60 for future pensioners currently aged 40, on the valuation date: – Males 29.1 29.0 – Females 31.7 31.6 (1) The discount rate and inflation related assumptions set out in the table above reflect the assumptions calculated based on the Scheme’s duration and cash flow profile as a whole. The actual assumptions used were determined for each section independently based on each section’s duration and cash flow profile. The majority of the liability movement over the half year was due to changes in market conditions. Actuarial assumption sensitivities The sensitivity analyses below have been determined based on reasonably possible changes of the respective assumptions occurring at the end of the reporting period, while holding all other assumptions constant. (Decrease)/increase Change in pension obligation at period end from 30 June 2022 31 December 2021 Assumption £m £m Discount rate 25 bps increase (335) (571) General price inflation 25 bps increase 239 392 Mortality Each additional year of longevity assumed 256 478

Contingent Liabilities and Comm

Contingent Liabilities and Commitments	6 Months Ended
	Jun. 30, 2022
Disclosure of contingent liabilities [abstract]
Contingent Liabilities and Commitments	26. CONTINGENT LIABILITIES AND COMMITMENTS 30 June 2022 31 December 2021 £m £m Guarantees given to third parties 428 363 Formal standby facilities, credit lines and other commitments 37,224 37,346 37,652 37,709 Other legal actions and regulatory matters Santander UK engages in discussion, and co-operates, with the FCA, PRA, CMA and other regulators and government agencies in various jurisdictions in their supervision and review of Santander UK including reviews exercised under statutory powers, regarding its interaction with past and present customers, both as part of general thematic work and in relation to specific products, services and activities. During the ordinary course of business, Santander UK is also subject to complaints and threatened legal proceedings brought by or on behalf of current or former employees, customers, investors or other third parties, in addition to legal and regulatory reviews, challenges and tax or enforcement investigations or proceedings in various jurisdictions. All such matters are assessed periodically to determine the likelihood of Santander UK incurring a liability. In those instances where it is concluded that it is not yet probable that a quantifiable payment will be made, for example because the facts are unclear or further time is required to fully assess the merits of the case or to reasonably quantify the expected payment, no provision is made. In addition, where it is not currently practicable to estimate the possible financial effect of these matters, no provision is made. FCA civil regulatory investigation into Santander UK plc financial crime systems, processes and controls, and compliance with the Money Laundering Regulations 2007 During HY 2022 Santander UK plc continued to cooperate with an FCA civil regulatory investigation which commenced in July 2017 into our compliance with the Money Laundering Regulations 2007 and potential breaches of FCA principles and rules relating to anti-money laundering and financial crime systems and controls. The FCA’s investigation focuses primarily on the period 2012 to 2017 and includes consideration of high-risk customers including Money Service Businesses. It is not currently possible to make a reliable assessment of any liability resulting from the investigation including any financial penalty. Payment Protection Insurance In relation to a specific PPI portfolio of complaints, a legal dispute regarding allocation of liability is in its early stages. The dispute relates to the liability for PPI mis-selling complaints relating to pre-2005 PPI policies underwritten by AXA France IARD and AXA France Vie (together, AXA France - previously Financial Insurance Company Ltd and Financial Assurance Company Ltd respectively) and involves Santander Cards UK Limited (a former GE Capital Corporation entity and distributor of pre-2005 PPI known as GE Capital Bank Limited which was acquired by Banco Santander SA in 2008 and subsequently transferred to Santander UK plc) and a Banco Santander SA subsidiary Santander Insurance Services UK Limited (together the Santander Entities). During the relevant period, AXA France were owned by Genworth Financial International Holdings, Inc (Genworth). In September 2015, AXA SA acquired AXA France from Genworth. In July 2017, the Santander Entities notified AXA France that they did not accept liability for losses on PPI policies relating to the relevant period. Santander UK plc entered into a Complaints Handling Agreement (CHA) with AXA France pursuant to which it agreed to handle complaints on their behalf, and AXA France agreed to pay redress assessed to be due to relevant policyholders on a without prejudice basis. A standstill agreement was entered into between the Santander Entities and AXA France as a condition of the CHA. In July 2020, Genworth announced that it had agreed to pay AXA SA circa £624m in respect of PPI mis-selling losses in settlement of the related dispute concerning obligations under the sale and purchase agreement pursuant to which Genworth sold AXA France to AXA SA. The CHA between Santander UK plc and AXA France terminated on 26 December 2020. On 30 December 2020, AXA France provided written notice to the Santander Entities to terminate the standstill agreement. During 2021, AXA France commenced litigation against the Santander Entities seeking recovery of £636m and any further losses relating to pre-2005 PPI. Judgment in respect of the Santander Entities application for AXA France’s claim to be struck out/summarily dismissed, was handed down by the Commercial Court on 12 July 2022. In summary, the Commercial Court upheld a significant part of the Santander Entities’ strike-out application, striking out AXA France’s claim for contribution against Santander for alleged losses and requiring AXA France to re-plead a significant portion of its other pleadings. The Santander Entities are seeking permission to appeal aspects of the strike out decision on which they were unsuccessful. Overall the dispute remains at an early stage and there are ongoing factual issues to be resolved which may have legal consequences including in relation to liability. These issues create uncertainties which mean that it is difficult to reliably predict the outcome or the timing of the resolution of the matter. The litigation and other regulatory provision in Note 24 includes our best estimate of the Santander Entities’ liability to the specific portfolio. Further information has not been provided on the basis that it would be seriously prejudicial to the Santander Entities’ interests in connection with the dispute. In addition, and in relation to PPI more generally the PPI provision includes an amount relating to legal claims challenging the FCA’s industry guidance on the treatment of Plevin / recurring non-disclosure assessments. This provision is based on current stock levels, future projected claims, and average redress. There remains a risk that volumes received in future may be higher than forecast. The provision in Note 24 includes our best estimate of Santander UK’s liability for the specific issue. The actual cost of customer compensation could differ from the amount provided. It is not currently practicable to provide an estimate of the risk and amount of any further financial impact. German dividend tax arbitrage transactions In June 2018 the Cologne Criminal Prosecution Office and the German Federal Tax Office commenced an investigation in relation to the historical involvement of Santander UK plc, Santander Financial Services plc and Cater Allen International Limited (all subsidiaries of Santander UK Group Holdings plc) in German dividend tax arbitrage transactions (known as cum/ex transactions). These transactions allegedly exploited a loophole of a specific German settlement mechanism through short-selling and complex derivative structuring which resulted in the German government either refunding withholding tax where such tax had not been paid or refunding it more than once. The German authorities are investigating numerous institutions and individuals in connection with alleged transactions and practices which may be found to be illegal under German law. During H122 we continued to cooperate with the German authorities and, with the assistance of external experts, to progress an internal investigation into the matters in question. From Santander UK plc’s perspective, the investigation is focused principally on the period 2009-2011 and remains on-going. There remain factual issues to be resolved which may have legal consequences including potentially material financial penalties. These issues create uncertainties which mean that it is difficult to predict the resolution of the matter including timing or the significance of the possible impact. Any potential losses, claims or expenses suffered or incurred by Santander Financial Services plc in respect of these matters have been fully indemnified by Santander UK plc, as part of the ring-fencing transfer scheme between Santander UK plc, Santander Financial Services plc and Banco Santander SA. Taxation The Santander UK group engages in discussion, and co-operates, with HM Revenue & Customs (HMRC) in their oversight of the Santander UK group’s tax matters. The Santander UK group adopted the UK’s Code of Practice on Taxation for Banks in 2010. Certain leases in which the Santander UK group is or was the lessor have been under review by HMRC in connection with claims for tax allowances. Under the terms of the lease agreements, the Santander UK group is fully indemnified in all material respects by the respective lessees for any liability arising from the disallowance of tax allowances plus accrued interest. During 2021, an outline agreement in principle in respect of a number of these lease arrangements was reached directly between the lessee and HMRC. This agreement was executed in April 2022, resulting in a final payment by the lessee to HMRC and the conclusion of HMRC’s review. There is no financial impact for the Santander UK group. Other On 2 November 2015, Visa Europe Ltd agreed to sell 100% of its share capital to Visa Inc. The deal closed on 21 June 2016. As a member and shareholder of Visa Europe Ltd, Santander UK received upfront consideration made up of cash and convertible preferred stock. C onversion of the preferred stock into Class A Common Stock of Visa Inc. depends on the outcome of litigation against Visa involving UK & Ireland (UK&I) multilateral interchange fees (MIFs). Following ring-fencing, all Visa stock is now held by Santander Equity Investments Limited (SEIL), outside the ring fenced bank. In addition, Santander UK and certain other UK&I banks have agreed to indemnify Visa Inc. in the event that the preferred stock is insufficient to meet the costs of this litigation. Visa Inc. has recourse to this indemnity once more than €1bn of losses relating to UK&I MIFs have arisen or once the total value of the preferred stock issued to UK&I banks on closing has been reduced to nil . Whilst Santander UK's liability under this indemnity is capped at €39.85m , Visa Inc. may have recourse to a general indemnity in place under Visa Europe Operating Regulations for damages not satisfied through the above mechanism. At this stage, it is unclear whether the litigation will give rise to more than €1bn of losses relating to UK&I MIFs which means it is difficult to predict the resolution of the matter including the timing or the significance of the possible impact. As part of the sale of subsidiaries, businesses and other entities, and as is normal in such circumstances, Santander UK plc (and/or, where relevant, its subsidiaries) has given warranties and indemnities to the purchasers.

Other Equity Instruments

Other Equity Instruments	6 Months Ended
	Jun. 30, 2022
Disclosure of classes of share capital [abstract]
Other Equity Instruments	27. OTHER EQUITY INSTRUMENTS Interest rate 30 June 2022 31 December 2021 % Next call date £m £m £300m Step-up Callable Perpetual Reserve Capital Instruments 7.037 February 2026 — 235 AT1 securities: - £500m Perpetual Capital Securities 6.75 June 2024 496 496 - £750m Perpetual Capital Securities 7.375 June 2022 — 750 - £500m Perpetual Capital Securities 5.18 n/a — — - £500m Perpetual Capital Securities 6.30 March 2025 500 500 - £210m Perpetual Capital Securities 4.25 March 2026 210 210 - £750m Perpetual Capital Securities 6.50 September 2027 750 — 1,956 2,191

Notes to Cash Flows

Notes to Cash Flows	6 Months Ended
	Jun. 30, 2022
Cash Flows Explanatory Notes [Abstract]
Notes to Cash Flows	28. NOTES TO CASH FLOWS Restatements in the consolidated cash flow Reverse repurchase agreements with a contractual maturity of greater than 3 months and repurchase agreements were previously included in cash and cash equivalents. As set out in the 2021 Annual Report, with effect from 31 December 2021, such agreements are no longer included in cash and cash equivalents, and have been included in the cash flow statement within ‘change in operating assets' and 'change in operating liabilities’ for ‘reverse repurchase agreements - non trading’ and ‘repurchase agreements - non trading’. Prior periods have been restated. As a result, at 30 June 2021, cash and cash equivalents have been increased by £4,339m. The presentation of the consolidated cash flow statement has changed to present 'profit before tax' within cash flows from operating activities instead of 'profit after tax'. Prior periods have been restated. As a result, at 30 June 2021, the adjustment for 'non-cash items included in profit' within cash flows from operating activities has been decreased by £214m . Following a decision by the IFRS Interpretations Committee in April 2022, Santander UK updated its accounting policy to exclude from cash and cash equivalents Reserves Collateralisation Accounts (RCAs) balances held at the BoE relating to Santander UK’s participation in certain payments schemes. Instead, RCAs balances are classified as restricted balances and included within 'change in operating assets' in the cash flow statement. Prior periods have been restated. As a result, opening cash and cash equivalents at 1 January 2022 and 1 January 2021 have been restated by £1,580m and £985m respectively. At 30 June 2021, cash and cash equivalents were reduced by £780m and restricted balances were increased by £780m.

Assets Charged as Security for

Assets Charged as Security for Liabilities and Collateral Accepted as Security for Assets	6 Months Ended
	Jun. 30, 2022
Disclosure Of Assets Pledged As Security [Abstract]
Assets Charged as Security for Liabilities and Collateral Accepted as Security for Assets	29. ASSETS CHARGED AS SECURITY FOR LIABILITIES AND COLLATERAL ACCEPTED AS SECURITY FOR ASSETS Securitisations and covered bonds As described in Note14 to the Consolidated Financial Statements in the 2021 Annual Report, Santander UK plc and certain of its subsidiaries issue securitisations and covered bonds. At 30 June 2022, there were £24,183m (2021: £20,199m) of gross assets in these secured programmes, of which £751m (2021: £767m) related to internally retained issuances that were available for use as collateral for liquidity purposes in the future. At 30 June 2022, a total of £1,780m (2021: £1,855m) of notes issued under securitisation and covered bond programmes had been retained internally, a proportion of which had been used as collateral via third party bilateral secured funding transactions, which totalled £500m at 30 June 2022 (2021: £500m), or for use as collateral for liquidity purposes in the future.

Related Party Disclosures

Related Party Disclosures	6 Months Ended
	Jun. 30, 2022
Disclosure of transactions between related parties [abstract]
Related Party Disclosures	30. RELATED PARTY DISCLOSURES The financial position and performance of the Santander UK group were not materially affected in H122 by any related party transactions, or changes to related party transactions, except for the following : In May 2022, Santander UK plc transferred a portfolio of mortgage assets with a book value of £624m to Santander Financial Services plc for a cash consideration of £631m , including a purchase price premium of £7m .

Financial Instruments

Financial Instruments	6 Months Ended
	Jun. 30, 2022
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Abstract]
Financial Instruments	31. FINANCIAL INSTRUMENTS a) Measurement basis of financial assets and liabilities Financial assets and financial liabilities are measured on an ongoing basis either at fair value or at amortised cost. Note 1 to the Consolidated Financial Statements in the 2021 Annual Report describes how the classes of financial instruments are measured, and how income and expenses, including fair value gains and losses, are recognised. b) Fair values of financial instruments carried at amortised cost The following tables analyse the fair value of the financial instruments carried at amortised cost at 30 June 2022 and 31 December 2021. It does not include fair value information for financial assets and financial liabilities carried at amortised cost if the carrying amount is a reasonable approximation of fair value. Details of the valuation methodology of the financial assets and financial liabilities carried at amortised cost can be found in Note 40(e) to the Consolidated Financial Statements in the 2021 Annual Report. 30 June 2022 31 December 2021 Fair value Carrying Fair value Carrying Level 1 Level 2 Level 3 Fair value value Level 1 Level 2 Level 3 Fair value value £m £m £m £m £m £m £m £m £m £m Assets Loans and advances to customers — — 215,234 215,234 217,012 — — 212,811 212,811 210,094 Loans and advances to banks — 793 — 793 793 — 1,169 — 1,169 1,169 Reverse repurchase agreements - non trading — 8,785 — 8,785 8,793 — 12,453 226 12,679 12,683 Other financial assets at amortised cost 151 — — 151 156 164 348 — 512 506 151 9,578 215,234 224,963 226,754 164 13,970 213,037 227,171 224,452 Liabilities Deposits by customers — 210 189,516 189,726 189,729 — 48 192,898 192,946 192,926 Deposits by banks — 35,012 63 35,075 35,182 — 33,770 85 33,855 33,855 Repurchase agreements - non trading — 6,910 — 6,910 6,910 — 11,718 — 11,718 11,718 Debt securities in issue 2,349 22,569 4,622 29,540 29,521 963 23,926 1,218 26,107 25,520 Subordinated liabilities 19 2,610 — 2,629 2,335 37 2,350 238 2,625 2,228 2,368 67,311 194,201 263,880 263,677 1,000 71,812 194,439 267,251 266,247 c) Fair values of financial instruments measured at fair value The following tables summarise the fair values of the financial assets and liabilities accounted for at fair value at 30 June 2022 and 31 December 2021, analysed by their levels in the fair value hierarchy - Level 1, Level 2 and Level 3. 30 June 2022 31 December 2021 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Valuation £m £m £m £m £m £m £m £m technique Assets Derivative financial instruments Exchange rate contracts — 1,909 — 1,909 — 1,193 1 1,194 A Interest rate contracts — 2,002 2 2,004 — 1,547 — 1,547 A & C Equity and credit contracts — 102 39 141 — 116 45 161 B & D Netting — (1,783) — (1,783) — (1,221) — (1,221) — 2,230 41 2,271 — 1,635 46 1,681 Other financial assets at FVTPL Loans and advances to customers — — 60 60 — — 74 74 A Debt securities — — 95 95 — — 111 111 A, B & D — — 155 155 — — 185 185 Financial assets at FVOCI Debt securities 4,894 — — 4,894 5,833 — — 5,833 D Loans and advances to customers — — 19 19 — — 18 18 D 4,894 — 19 4,913 5,833 — 18 5,851 Total assets at fair value 4,894 2,230 215 7,339 5,833 1,635 249 7,717 Liabilities Derivative financial instruments Exchange rate contracts — 427 — 427 — 506 — 506 A Interest rate contracts — 2,038 3 2,041 — 1,436 2 1,438 A & C Equity and credit contracts — 22 13 35 — 24 30 54 B & D Netting — (1,783) — (1,783) — (1,221) — (1,221) — 704 16 720 — 745 32 777 Other financial liabilities at FVTPL Debt securities in issue — 463 3 466 — 555 5 560 A Structured deposits — 346 — 346 — 223 — 223 A Collateral and associated financial guarantees — 15 — 15 — 19 1 20 D — 824 3 827 — 797 6 803 Total liabilities at fair value — 1,528 19 1,547 — 1,542 38 1,580 Transfers between levels of the fair value hierarchy In H122 there were no significant (H121: no significant) transfers of financial instruments between levels of the fair value hierarchy. d) Valuation techniques The main valuation techniques employed in internal models to measure the fair value of the financial instruments are disclosed in Note 40(c) to the Consolidated Financial Statements in the 2021 Annual Report. The Santander UK group did not make any material changes to the valuation techniques and internal models it used in H122. e) Fair value adjustments The internal models incorporate assumptions that Santander UK believes would be made by a market participant to establish fair value. Fair value adjustments are adopted when Santander UK considers that there are additional factors that would be considered by a market participant that are not incorporated in the valuation model. Santander UK classifies fair value adjustments as either ‘risk-related’ or ‘model-related’. The fair value adjustments form part of the portfolio fair value and are included in the balance sheet values of the product types to which they have been applied. The magnitude and types of fair value adjustment are listed in the following table: 30 June 2022 31 December 2021 £m £m Risk-related: - Bid-offer and trade specific adjustments (15) (9) - Uncertainty 15 20 - Credit risk adjustment 6 6 - Funding fair value adjustment 4 3 10 20 Risk-related adjustments Risk-related adjustments are driven, in part, by the magnitude of Santander UK’s market or credit risk exposure, and by external market factors, such as the size of market spreads. For more details, see ‘Risk-related adjustments’ in Note 40(g) to the Consolidated Financial Statements in the 2021 Annual Report. f) Internal models based on information other than market data (Level 3) Valuation techniques There have been no significant changes to the valuation techniques as set out in Note 40(h) to the Consolidated Financial Statements in the 2021 Annual Report. Reconciliation of fair value measurement in Level 3 of the fair value hierarchy The following table sets out the movements in Level 3 financial instruments in H122: Assets Liabilities Derivatives Other financial assets at FVTPL Financial assets at FVOCI Total Derivatives Other financial liabilities at FVTPL Total £m £m £m £m £m £m £m At 1 January 2022 46 185 18 249 (32) (6) (38) Total (losses)/gains recognised: Fair value movements (2) (2) (18) 1 (19) — 5 5 Transfers in — — — — (2) — (2) Netting (1) — — — — — (4) (4) Settlements (3) (12) — (15) 18 2 20 At 30 June 2022 41 155 19 215 (16) (3) (19) Gains/(losses) recognised in profit or loss/other comprehensive income relating to assets and liabilities held at the end of the period (2) (2) (18) 1 (19) — 5 5 (1) This relates to the effect of netting on the fair value of the credit linked notes due to a legal right of set-off between the principal amounts of the senior notes and the associated cash deposits. For more, see ‘ii) Credit protection entities’ in Note 19 to the Consolidated Financial Statements in the 2021 Annual Report. (2) Fair value movements relating to derivatives and other financial assets at FVTPL are recognised in other operating income in the income statement. Fair value movements relating to financial assets at FVOCI are recognised in the movement in fair value reserve (debt instruments). Effect of changes in significant unobservable assumptions to reasonably possible alternatives (Level 3) There has been no significant change to the unobservable inputs and sensitivities used in Level 3 fair values as set out in Note 40(h) to the Consolidated Financial Statements in the 2021 Annual Report.

Interest Rate Benchmark Reform

Interest Rate Benchmark Reform	6 Months Ended
	Jun. 30, 2022
Interest Rate Benchmark Reform [Abstract]
Interest Rate Benchmark Reform	32. INTEREST RATE BENCHMARK REFORM The following tables show the notional amounts of assets, liabilities and off-balance sheet commitments at 30 June 2022 and 31 December 2021 affected by IBOR reform that have yet to transition to an alternative benchmark interest rate as provided internally to key management personnel. 30 June 2022 GBP (2) LIBOR USD (2) LIBOR Other (2) Total £m £m £m £m Assets Derivatives (1) — 1,650 — 1,650 Financial assets at amortised cost 85 17 — 102 85 1,667 — 1,752 Liabilities Derivatives (1) 130 1,830 — 1,960 Other financial liabilities at fair value through profit and loss — 3 — 3 130 1,833 — 1,963 Off-balance sheet commitments given 8 79 — 87 31 December 2021 GBP (2) LIBOR USD (2) LIBOR Other (2) Total £m £m £m £m Assets Derivatives (1) — 1,480 — 1,480 Other financial assets at fair value through profit and loss 8 — — 8 Financial assets at amortised cost 1,373 81 1 1,455 1,381 1,561 1 2,943 Liabilities Derivatives (1) 338 1,831 — 2,169 Other financial liabilities at fair value through profit and loss — 5 — 5 Financial liabilities at amortised cost 34 185 — 219 372 2,021 — 2,393 Off-balance sheet commitments given 338 59 — 397 (1) Many of the Santander UK group's derivatives subject to IBOR reform are standard ISDA contracts and are subject to supplementary ISDA fallback provisions which became effective on 25 January 2021 setting out what floating rates apply on the permanent discontinuation of key IBORs. The Santander UK group adhered to the protocol and implemented the fallback provisions to derivative contracts entered into before 25 January 2021. Where derivative counterparties also adhered to the protocol, fallback provisions were automatically implemented in existing derivative contracts when the supplement became effective. 1-month, 3-month and 6-month GBP & JPY settings for certain legacy contracts have been extended until at least the end of 2022 but not for cleared derivative contracts. (2) Settings for GBP, JPY & NOK LIBOR & 1-week and 2-month USD LIBOR ceased on 31 December 2021 and for EONIA on 3 January 2022, however, for certain legacy contracts, 1-month, 3-month and 6-month settings for GBP & JPY LIBOR have been extended until at least 31 December 2022. Remaining USD LIBOR settings (overnight, 1-month, 3-month, 6-month and 12-month) will cease on 30 June 2023. IBOR Reform The table below shows the notional amount of derivatives in hedging relationships directly affected by uncertainties related to IBOR reform. 30 June 2022 31 December 2021 GBP USD Other Total GBP USD Other Total £m £m £m £m £m £m £m £m Total notional value of hedging instruments – Cash flow hedges — 2,881 — 2,881 — 2,586 — 2,586 – Fair value hedges — 176 — 176 — 160 — 160 — 3,057 — 3,057 — 2,746 — 2,746 Maturing after cessation date (1) – Cash flow hedges — 2,881 — 2,881 — 2,586 — 2,586 – Fair value hedges — 176 — 176 — 160 — 160 — 3,057 — 3,057 — 2,746 — 2,746 (1) Settings for GBP, JPY & NOK LIBOR & 1-week and 2-month USD LIBOR ceased on 31 December 2021 and for EONIA on 3 January 2022, however, for certain legacy contracts, 1-month, 3-month and 6-month settings for GBP & JPY LIBOR have been extended until at least 31 December 2022. Remaining USD LIBOR settings (overnight, 1-month, 3-month, 6-month and 12-month) will cease on 30 June 2023. For more details on interest rate benchmark reform and the Santander UK group’s transition from IBORs to alternative benchmark rates, see Note 42 to the Consolidated Financial Statements in the 2021 Annual Report.

Discontinued Operations and Ass

Discontinued Operations and Assets Held for Sale	6 Months Ended
	Jun. 30, 2022
Discontinued Operations and Assets and Liabilities Held for Sale [Abstract]
Discontinued Operations	33. DISCONTINUED OPERATIONS AND ASSETS HELD FOR SALE Discontinued operations Transfer of the CIB Business Santander UK plc transferred a significant part of its Corporate & Investment Banking business to the London branch of Banco Santander SA under a Part VII banking business transfer scheme, which completed on 11 October 2021. The residual parts of the Corporate & Investment Banking business have been wound down or transferred to other segments. For the periods prior to its sale, the Corporate & Investment Banking business met the requirements for presentation as discontinued operations. The financial performance and cash flow information relating to the discontinued operations were as follows: For the Half Year to 30 June 2022 30 June 2021 £m £m Net interest income — 24 Net fee and commission income — 27 Total operating income — 51 Operating expenses before credit impairment losses, provisions and charges — (22) Credit impairment losses — 7 Provisions for other liabilities and charges — (3) Total operating credit impairment losses, provisions and charges — 4 Profit from discontinued operations before tax — 33 Tax on profit from discontinued operations — (9) Profit from discontinued operations after tax — 24 There were no gains or losses recognised on the measurement to fair value less costs to sell or on the disposal of the asset groups constituting the discontinued operations. In H122, the net cash flows attributable to the operating activities, investing activities and financing activities in respect of discontinued operations were £nil outflow (H121: £1,754m ou tflow), £nil (H121: £nil) and £nil ( H121: £nil) respectively. Assets held for sale Sale of property Management considered the sale of Santander House and Shenley Wood freehold land and buildings to be highly probable at the balance sheet date. As such, the Santander UK group reclassified these properties as held for sale. The sale is expected to complete in H2 2023 with no gain or loss. At 30 June 2022, assets held for sale comprised: £m Assets Property, plant and equipment 49 Total assets held for sale 49

Events After the Balance Sheet

Events After the Balance Sheet Date	6 Months Ended
	Jun. 30, 2022
Disclosure of non-adjusting events after reporting period [abstract]
Events After the Balance Sheet Date	34. EVENTS AFTER THE BALANCE SHEET DATE There have been no significant events between 30 June 2022 and the date of approval of these financial statements which would require a change to or additional disclosure in the financial statements.

Accounting Policies (Policies)

Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2022
Disclosure Of Significant Accounting Policies [Abstract]
Basis of preparation and accounting developments	The financial information in these Condensed Consolidated Interim Financial Statements is unaudited and does not constitute statutory accounts as defined in section 434 of the UK Companies Act 2006. These Condensed Consolidated Interim Financial Statements were approved by the Board of Directors on 11 August 2022. Statutory accounts for the year ended 31 December 2021 have been delivered to the Registrar of Companies. The Condensed Consolidated Interim Financial Statements reflect all adjustments that, in the opinion of management, are necessary for a fair statement of the results of operations for the interim period. All such adjustments to the financial information are of a normal, recurring nature. Because the results from common banking activities are so closely related and responsive to changes in market conditions, the results for any interim period are not necessarily indicative of the results that can be expected for the year. The Condensed Consolidated Interim Financial Statements have been prepared in accordance with International Accounting Standard IAS 34 ‘Interim Financial Reporting', as issued by the International Accounting Standards Board (IASB) and adopted in the UK, and the Disclosure Guidance and Transparency Rules sourcebook of the UK's Financial Conduct Authority (FCA). They do not include all the information and disclosures normally required for full annual financial statements and should be read in conjunction with the Consolidated Financial Statements of Santander UK plc (the Company) and its subsidiaries (collectively Santander UK or the Santander UK group) for the year ended 31 December 2021 which were prepared in accordance with UK-adopted International Accounting Standards (IAS). Those consolidated financial statements were also prepared in accordance with IFRSs as issued by the IASB, including interpretations issued by the IFRS Interpretations Committee, as there were no applicable differences from IFRSs as issued by the IASB for the periods presented. Except as noted below, the same accounting policies, presentation and methods of computation are followed in these Condensed Consolidated Interim Financial Statements as were applied in the presentation of Santander UK’s 2021 Annual Report. Future accounting developments Disclosure of Accounting Policies – Amendments to IAS 1 and IFRS Practice Statement 2
Property, plant and equipment	Property, plant and equipment During H122, Santander UK expanded its accounting policy for 'Property, plant and equipment' to separately address properties which it no longer occupies, and to identify such properties as ‘Investment property’. This change had no financial impact on these Condensed Consolidated Interim Financial Statements. Property that is held for long-term rental yields or for capital appreciation or both, and that is not occupied by the companies in the Santander UK group, is classified as investment property and included in property, plant and equipment. Investment property is accounted for in the same manner as owner-occupied property. In addition, rental income from investment property is recognised as other revenue on a straight-line basis over the term of the lease. Lease incentives granted are recognised as an integral part of the total rental income, over the term of the lease.
Cash and cash equivalents	Cash and cash equivalents Following a decision by the IFRS Interpretations Committee in April 2022, Santander UK updated its accounting policy to exclude from cash and cash equivalents Reserves Collateralisation Accounts (RCAs) balances held at the BoE relating to Santander UK’s participation in certain payments schemes. Instead, RCAs balances are classified as restricted balances and included within 'change in operating assets' in the cash flow statement. Prior periods have been restated. For the purposes of the cash flow statement, cash and cash equivalents comprise balances with less than three months maturity from the date of acquisition, including cash and non-restricted balances with central banks, treasury bills and other eligible bills, loans and advances to banks and short-term investments in securities. Balances with central banks represent amounts held at the BoE as part of the Santander UK group’s liquidity management activities. It includes certain minimum cash ratio deposits held for regulatory purposes and reserves collateralised accounts in respect of Santander UK’s participation in certain payments schemes which are required to be maintained with the BoE and are restricted balances.
Non-current assets held for sale	Non-current assets held for sale Non-current assets (or disposal groups) are classified as held for sale when their carrying amount is to be recovered principally through a sale transaction rather than continuing use. In order to be classified as held for sale, the asset must be available for immediate sale in its present condition subject only to terms that are usual and customary, and the sale must be highly probable. Non-current assets (or disposal groups) held for sale are measured at the lower of carrying amount and fair value less cost to sell, with the exception of financial instruments which remain governed by the requirements of IFRS 9 and are held at their IFRS 9 carrying value.
Going concern	Going concern In light of the continuing economic uncertainty, the Directors updated their going concern assessment in preparing these Condensed Consolidated Interim Financial Statements. After making enquiries, the Directors have a reasonable expectation that Santander UK has adequate resources to continue in operational existence for at least twelve months from the date of this report and, therefore, having reassessed the principal risks and uncertainties, the Directors consider it appropriate for the Condensed Consolidated Interim Financial Statements to be prepared on a going concern basis. In making their going concern assessment in connection with preparing the Condensed Consolidated Interim Financial Statements, the Directors considered a wide range of information that included Santander UK’s long-term business and strategic plans, forecasts and projections, estimated capital, funding and liquidity requirements, contingent liabilities and the reasonably possible changes in trading performance arising from potential economic, market and product developments.
Critical judgements and accounting estimates	CRITICAL JUDGEMENTS AND ACCOUNTING ESTIMATES The preparation of the Condensed Consolidated Interim Financial Statements requires management to make judgements and accounting estimates that affect the reported amount of assets and liabilities at the reporting date and the reported amount of income and expenses during the reporting period. Management evaluates its judgements and accounting estimates, which are based on historical experience and on various other factors that are believed to be reasonable under the circumstances, on an ongoing basis. Actual results may differ from these accounting estimates under different assumptions or conditions. In preparing the Condensed Consolidated Interim Financial Statements, no significant judgements were made in applying the accounting policies, other than those involving estimations about credit impairment losses, provisions and contingent liabilities, pensions and goodwill. There has been no change in the inherent sensitivity of the areas of judgement in the period. Management have considered the impact of developments in principal risks and uncertainties, as set out in the Risk review, on critical judgements and accounting estimates. a) Credit impairment losses Key judgements – Determining an appropriate definition of default – Establishing the criteria for a significant increase in credit risk (SICR) and, for corporate borrowers, internal credit risk rating – Determining appropriate post model adjustments – Assessing individual corporate Stage 3 exposures Key estimates – Forward-looking multiple economic scenario assumptions – Probability weights assigned to multiple economic scenarios For more on each of these key judgements and estimates, see 'Critical judgements and accounting estimates applied in calculating ECL' in the ‘Credit risk – credit risk management’ section of the Risk review in the 2021 Annual Report. Sensitivity of ECL allowance For detailed disclosures, see 'Sensitivity of ECL allowance' in the ‘Credit risk – credit risk management’ section of the Risk review. b) Provisions and contingent liabilities Key judgements – Determining whether a present obligation exists – Assessing the likely outcome of future legal decisions Key estimates – Probability, timing, nature and amount of any outflows that may arise from past events Included in Litigation and other regulatory provisions in Note 24 are amounts in respect of management’s best estimates of liability relating to a legal dispute regarding allocation of responsibility for a specific PPI portfolio of complaints, and Plevin related litigation. Note 26 provides disclosure relating to ongoing factual issues and reviews that could impact the timing and amount of any outflows. Note 26 includes disclosure relating to an investigation in relation to the historical involvement of Santander UK plc, Santander Financial Services plc and Cater Allen International Limited (all subsidiaries of Santander UK Group Holdings plc) in German dividend tax arbitrage transactions, as well as an FCA civil regulatory investigation which commenced in July 2017 into our compliance with the Money Laundering Regulations 2007 and potential breaches of FCA principles and rules relating to anti-money laundering and financial crime systems and controls. These judgements are based on the specific facts available and often require specialist professional advice. There can be a wide range of possible outcomes and uncertainties, particularly in relation to legal actions, and regulatory and consumer credit matters. As a result, it is often not possible to make reliable estimates of the likelihood and amount of any potential outflows, or to calculate any resulting sensitivities. For more on these key judgements and estimates, see Notes 24 and 26. c) Pensions Key judgements – Setting the criteria for constructing the corporate bond yield curve used to determine the discount rate – Determining the methodology for setting the inflation assumption Key estimates – Discount rate applied to future cash flows – Rate of price inflation – Expected lifetime of the schemes' members – Valuation of pension fund assets whose values are not based on market observable data For more on each of these key judgements and estimates, see Note 25. Sensitivity of defined benefit pension scheme estimates For detailed disclosures, see ‘Actuarial assumption sensitivities’ in Note 25. The Scheme was invested in certain assets whose values are not based on market observable data, such as investments in private equity funds and property. Due diligence has been conducted to ensure the values obtained in respect of these assets are appropriate and represent fair value. Given the nature of these investments, we are unable to prepare sensitivities on how their values could vary as market conditions or other variables change. d) Goodwill Key judgements: – Determining the basis of goodwill impairment calculation assumptions, including management's planning assumptions considering internal capital allocations needed to support Santander UK's strategy, current market conditions and the macro-economic outlook. Key estimates: – Forecast cash flows for cash generating units, including estimated allocations of regulatory capital – Growth rate beyond initial cash flow projections – Discount rates which factor in risk-free rates and applicable risk premiums All of these variables are subject to fluctuations in external market rates and economic conditions beyond management’s control For more on each of these key judgements and estimates, see Note 16. Sensitivity of goodwill
Resegmentation of Retail Banking business	As reflected in the 2021 Annual Report, the segmental basis of presentation in these Condensed Consolidated Interim Financial Statements changed following a management review of our structure in Q4 2021. Previously, Consumer Finance was managed as part of Retail Banking. Santander UK plc transferred a significant part of its Corporate & Investment Banking business to the London branch of Banco Santander SA under a Part VII banking business transfer scheme, which completed on 11 October 2021. The residual parts of the Corporate & Investment Banking business have been wound down or transferred to other segments. For the periods prior to its sale, the Corporate & Investment Banking business met the requirements for presentation as discontinued operations. For more details, see Note 33.

Accounting Policies (Tables)

Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2022
Disclosure Of Significant Accounting Policies [Abstract]
Disclosure of Information about Key Judgements and Key Estimates	Key judgements – Determining an appropriate definition of default – Establishing the criteria for a significant increase in credit risk (SICR) and, for corporate borrowers, internal credit risk rating – Determining appropriate post model adjustments – Assessing individual corporate Stage 3 exposures Key estimates – Forward-looking multiple economic scenario assumptions – Probability weights assigned to multiple economic scenarios Key judgements – Determining whether a present obligation exists – Assessing the likely outcome of future legal decisions Key estimates – Probability, timing, nature and amount of any outflows that may arise from past events Key judgements – Setting the criteria for constructing the corporate bond yield curve used to determine the discount rate – Determining the methodology for setting the inflation assumption Key estimates – Discount rate applied to future cash flows – Rate of price inflation – Expected lifetime of the schemes' members – Valuation of pension fund assets whose values are not based on market observable data Key judgements: – Determining the basis of goodwill impairment calculation assumptions, including management's planning assumptions considering internal capital allocations needed to support Santander UK's strategy, current market conditions and the macro-economic outlook. Key estimates: – Forecast cash flows for cash generating units, including estimated allocations of regulatory capital – Growth rate beyond initial cash flow projections – Discount rates which factor in risk-free rates and applicable risk premiums All of these variables are subject to fluctuations in external market rates and economic conditions beyond management’s control

Segments (Tables)

Segments (Tables)	6 Months Ended
	Jun. 30, 2022
Disclosure of operating segments [abstract]
Summary of Results by Segment	Results by segment For the Half Year to Retail Banking Consumer Finance Corporate & Commercial Banking Corporate Centre Total 30 June 2022 £m £m £m £m £m Net interest income 1,784 92 242 2 2,120 Non-interest income 116 101 69 (16) 270 Total operating income 1,900 193 311 (14) 2,390 Operating expenses before credit impairment (losses)/write-backs, provisions and charges (831) (73) (181) (87) (1,172) Credit impairment (losses)/write-backs (126) (13) 19 2 (118) Provisions for other liabilities and charges (101) — (2) (15) (118) Total operating credit impairment (losses)/write-backs, provisions and charges (227) (13) 17 (13) (236) Profit/(loss) from continuing operations before tax 842 107 147 (114) 982 Revenue from external customers 2,033 243 318 (204) 2,390 Inter-segment revenue (133) (50) (7) 190 — Total operating income 1,900 193 311 (14) 2,390 Revenue from external customers includes the following fee and commission income disaggregated by income type: (1) – Current account and debit card fees 218 — 29 — 247 – Insurance, protection and investments 31 — — — 31 – Credit cards 46 — — — 46 – Non-banking and other fees (2) 4 8 36 5 53 Total fee and commission income 299 8 65 5 377 Fee and commission expense (191) — (11) (7) (209) Net fee and commission income/(expense) 108 8 54 (2) 168 Customer loans 189,318 5,129 17,358 1,711 213,516 Total assets (3) 196,505 9,652 17,358 60,802 284,317 Of which assets held for sale — — — 49 49 Customer deposits 154,759 — 25,305 3,940 184,004 Total liabilities 155,199 1,153 25,326 86,966 268,644 (1) The disaggregation of fees and commission income as shown above is not included in reports provided to the chief operating decision maker but is provided to show the split by reportable segments. (2) Non-banking and other fees include mortgages (except mortgage account fees), consumer finance, commitment commission, asset finance, invoice finance and trade finance. (3) Includes customer loans, net of credit impairment loss allowances. Retail Banking (4) Consumer Finance (4) Corporate & Commercial Banking Corporate & Investment Banking Corporate Centre Total 30 June 2021 £m £m £m £m £m £m Net interest income/(expense) 1,602 135 202 — (34) 1,905 Non-interest income 109 77 51 — 49 286 Total operating income 1,711 212 253 — 15 2,191 Operating expenses before credit impairment (losses)/write-backs, provisions and charges (858) (90) (181) — (199) (1,328) Credit impairment (losses)/write-backs 28 20 23 — (1) 70 Provisions for other liabilities and charges (67) — (5) — (118) (190) Total operating credit impairment (losses)/write-backs, provisions and charges (39) 20 18 — (119) (120) Profit/(loss) from continuing operations before tax 814 142 90 — (303) 743 Revenue from external customers 1,939 255 272 — (275) 2,191 Inter-segment revenue (228) (43) (19) — 290 — Total operating income/(expense) 1,711 212 253 — 15 2,191 Revenue from external customers includes the following fee and commission income disaggregated by income type: (1) – Current account and debit card fees 172 — 23 — — 195 – Insurance, protection and investments 32 — — — — 32 – Credit cards 37 — — — — 37 – Non-banking and other fees (2) 1 4 29 — 7 41 Total fee and commission income 242 4 52 — 7 305 Fee and commission expense (136) — (10) — (8) (154) Net fee and commission income 106 4 42 — (1) 151 31 December 2021 Customer loans 183,023 4,984 16,997 — 2,284 207,288 Total assets (3) 190,629 8,873 16,997 — 70,599 287,098 Customer deposits 156,991 — 25,597 — 3,627 186,215 Total liabilities 157,622 1,173 25,613 — 86,588 270,996 (1) The disaggregation of fees and commission income as shown above is not included in reports provided to the chief operating decision maker but is provided to show the split by reportable segments. (2) Non-banking and other fees include mortgages (except mortgage account fees), consumer finance, commitment commission, asset finance, invoice finance and trade finance. (3) Includes customer loans, net of credit impairment loss allowances. (4) Restated to reflect the resegmentation of the Retail Banking segment into the Retail Banking and Consumer Finance segments described above, and a refinement of our fee and commission income disaggregation.

Operating Expenses Before Cre_2

Operating Expenses Before Credit Impairment Losses, Provisions and Charges (Tables)	6 Months Ended
	Jun. 30, 2022
Expenses by nature [abstract]
Summary of Operating Expenses Before Credit Impairment Losses, Provisions and Charges	30 June 2022 30 June 2021 £m £m Staff costs 556 577 Other administration expenses 458 431 Depreciation, amortisation and impairment 158 320 1,172 1,328

Credit Impairment Losses and _2

Credit Impairment Losses and Provisions (Tables)	6 Months Ended
	Jun. 30, 2022
Disclosure Of Credit Impairment Loss And Provisions [Abstract]
Summary of Impairment Losses and Provisions	30 June 2022 30 June 2021 £m £m Credit impairment losses/(write-backs): Loans and advances to customers 114 (33) Recoveries of loans and advances, net of collection costs (6) (13) Off-balance sheet exposures (See Note 24) 10 (24) 118 (70) Provisions for other liabilities and charges (excluding off-balance sheet credit exposures) (See Note 24) 121 191 Releases for residual value and voluntary termination (3) (1) 118 190 236 120

Taxation (Tables)

Taxation (Tables)	6 Months Ended
	Jun. 30, 2022
Major components of tax expense (income) [abstract]
Schedule of Tax on Profit Before Tax Differs from Theoretical Amount that Arise Using Basic Corporation Tax Rate	The Santander UK group’s effective tax rate for H122 was 23.6% (H121: 27.6%). The tax on profit from continuing operations before tax differs from the theoretical amount that would arise using the basic corporation tax rate as follows: For the Half Year to 30 June 2022 30 June 2021 £m £m Profit from continuing operations before tax 982 743 Tax calculated at a tax rate of 19% (H121: 19%) 187 141 Bank surcharge on profits 70 49 Non-deductible preference dividends paid 5 6 Non-deductible UK Bank Levy 8 14 Non-deductible conduct remediation, fines and penalties (1) — Other non-deductible costs and non-taxable income 8 14 Effect of change in tax rate on deferred tax provision (23) 13 Tax relief on dividends in respect of other equity instruments (22) (32) Tax on profit from continuing operations 232 205

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2022
Disclosure of nature and extent of risks arising from financial instruments [abstract]
Disclosure of Notional Amounts and Fair Values of Derivatives	30 June 2022 31 December 2021 Fair value Fair value Notional amount Assets Liabilities Notional amount Assets Liabilities £m £m £m £m £m £m Derivatives held for trading: Exchange rate contracts 13,712 287 314 11,036 159 168 Interest rate contracts 29,363 404 602 25,148 463 485 Equity and credit contracts 1,005 141 35 1,056 161 54 Total derivatives held for trading 44,080 832 951 37,240 783 707 Derivatives held for hedging Designated as fair value hedges: Exchange rate contracts 490 20 2 590 39 — Interest rate contracts 83,070 1,377 447 80,514 904 737 83,560 1,397 449 81,104 943 737 Designated as cash flow hedges: Exchange rate contracts 24,636 1,602 111 22,239 996 338 Interest rate contracts 25,361 223 992 21,466 180 216 49,997 1,825 1,103 43,705 1,176 554 Total derivatives held for hedging 133,557 3,222 1,552 124,809 2,119 1,291 Derivative netting (1) (1,783) (1,783) (1,221) (1,221) Total derivatives 177,637 2,271 720 162,049 1,681 777 (1) Derivative netting excludes the effect of cash collateral, which is offset against the gross derivative position. The amount of cash collateral received that had been offset against the gross derivative assets was £557m ( 2021 : £189m ) and the amount of cash collateral paid that had been offset against the gross derivative liabilities was £557m ( 2021 : £202m ).

Other Financial Assets at Fai_2

Other Financial Assets at Fair Value Through Profit or Loss (Tables)	6 Months Ended
	Jun. 30, 2022
Financial assets at fair value through profit or loss [abstract]
Summary of Other Financial Assets at Fair Value Through Profit or Loss	30 June 2022 31 December 2021 £m £m Loans and advances to customers: Loans to housing associations 11 12 Other loans 49 62 60 74 Debt securities 95 111 155 185

Loans and Advances to Custome_2

Loans and Advances to Customers (Tables)	6 Months Ended
	Jun. 30, 2022
Net Loans And Advances To Customers [Abstract]
Summary of Net Loans and Advances to Customers	30 June 2022 31 December 2021 £m £m Loans and advances to customers 217,910 210,947 Credit impairment loss allowances on loans and advances to customers (876) (828) Residual value and voluntary termination provisions on finance leases (22) (25) Net loans and advances to customers 217,012 210,094

Securitisations and Covered B_2

Securitisations and Covered Bonds (Tables)	6 Months Ended
	Jun. 30, 2022
Disclosure Of Securitisations And Covered Bonds [Abstract]
Disclosure of Analysis of Securitisations and Covered Bonds	The gross assets securitised, or for the covered bond programme assigned at 30 June 2022 and 31 December 2021 were: 30 June 2022 31 December 2021 £m £m Mortgage-backed master trust structures: – Holmes 2,010 2,294 – Fosse 1,910 2,154 3,920 4,448 Other asset-backed securitisation structures: – Motor 18 38 18 38 Total securitisation programmes 3,938 4,486 Covered bond programmes – Euro 35bn Global Covered Bond Programme 20,245 15,713 Total securitisation and covered bond programmes 24,183 20,199
Summary of Issuances and Redemptions of Securitisation and Covered Bond Programme	The following table sets out the internal and external issuances and redemptions in H122 and H121 for each securitisation and covered bond programme. Internal issuances External issuances Internal redemptions External redemptions H122 H121 H122 H121 H122 H121 H122 H121 £bn £bn £bn £bn £bn £bn £bn £bn Mortgage-backed master trust structures: – Holmes — — — — — — — 0.3 – Langton — — — — — 2.4 — — Other asset-backed securitisation structures: – Motor — — — — — 0.1 — — – Auto ABS UK Loans — — — — — 0.1 — 0.1 Covered bond programme — — — — — — — 4.5 — — — — — 2.6 — 4.9

Reverse Repurchase Agreements_2

Reverse Repurchase Agreements - Non Trading (Tables)	6 Months Ended
	Jun. 30, 2022
Disclosure Of Reserve Repurchase Agreements Non-Trading [Abstract]
Summary of Reverse Repurchase Agreements - Non Trading	30 June 2022 31 December 2021 £m £m Agreements with banks 475 447 Agreements with customers 8,318 12,236 8,793 12,683

Other Financial Assets at Amo_2

Other Financial Assets at Amortised Cost (Tables)	6 Months Ended
	Jun. 30, 2022
Financial assets at fair value through profit or loss [abstract]
Summary of Other Financial Assets at Amortised Cost	30 June 2022 31 December 2021 £m £m Asset backed securities 94 443 Debt securities 62 63 0 156 506

Financial Assets at Fair Valu_2

Financial Assets at Fair Value Through Other Comprehensive Income (Tables)	6 Months Ended
	Jun. 30, 2022
Financial assets at fair value through other comprehensive income [abstract]
Summary of Financial Assets at Fair Value Through Other Comprehensive Income	30 June 2022 31 December 2021 £m £m Debt securities 4,894 5,833 Loans and advances to customers 19 18 4,913 5,851

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	6 Months Ended
	Jun. 30, 2022
Property, plant and equipment [abstract]
Disclosure of Detailed Information about Property, Plant and Equipment	Property Office fixtures and equipment Computer software Operating lease assets Right-of-use assets Total (1) £m £m £m £m £m £m Cost: At 1 January 2022 978 1,049 434 755 254 3,470 Additions 31 29 — 112 32 204 Reclassification to assets held for sale (109) (31) — — — (140) Disposals (25) (268) (363) (126) (23) (805) At 30 June 2022 875 779 71 741 263 2,729 Accumulated depreciation: At 1 January 2022 334 857 434 160 137 1,922 Charge for the period 10 34 — 41 9 94 Impairment during the period 8 2 — — — 10 Reclassification to assets held for sale (62) (29) — — — (91) Disposals (16) (265) (363) (51) (1) (696) At 30 June 2022 274 599 71 150 145 1,239 Net book value 601 180 — 591 118 1,490 (1) Property, plant and equipment includes assets under construction of £155m (2021: £106m) and investment properties of £20m (2021: £17m).

Other Financial Liabilities a_2

Other Financial Liabilities at Fair Value Through Profit or Loss (Tables)	6 Months Ended
	Jun. 30, 2022
Disclosure of financial liabilities [abstract]
Summary of Other Financial Liabilities at Fair Value Through Profit or Loss	30 June 2022 31 December 2021 £m £m US$30bn Euro Medium Term Note Programme 3 5 Structured Notes Programmes 353 413 Eurobonds 110 142 Structured deposits 346 223 Collateral and associated financial guarantees 15 20 827 803

Deposits by Customers (Tables)

Deposits by Customers (Tables)	6 Months Ended
	Jun. 30, 2022
Deposits from customers [abstract]
Schedule of Deposits by Customers	30 June 2022 31 December 2021 £m £m Demand and time deposits (1) 183,553 185,843 Amounts due to other Santander UK Group Holdings plc subsidiaries 63 59 Amounts due to Santander UK Group Holdings plc (2) 4,987 5,874 Amounts due to fellow Banco Santander subsidiaries and joint ventures 1,126 1,150 189,729 192,926 (1) Includes equity index-linked deposits of £520m (2021: £549m). The capital amount guaranteed/protected and the amount of return guaranteed in respect of the equity index-linked deposits were £520m and £2m (2021: £549m and £2m) respectively. (2) Includes downstreamed funding from our immediate parent company Santander UK Group Holdings plc.

Deposits by Banks (Tables)

Deposits by Banks (Tables)	6 Months Ended
	Jun. 30, 2022
Disclosure Of Deposits From Banks [Abstract]
Schedule of Deposits by Banks	30 June 2022 31 December 2021 £m £m Items in the course of transmission 447 414 Deposits held as collateral 1,627 931 Other deposits (1) 33,105 32,507 Amounts due to Santander UK subsidiaries 3 3 35,182 33,855 (1) Includes drawdown from the TFS of £0.0bn (2021:£0.0bn) and drawdown from the TFSME of

Repurchase Agreements - Non T_2

Repurchase Agreements - Non Trading (Tables)	6 Months Ended
	Jun. 30, 2022
Disclosure Of Repurchase Agreements [Abstract]
Summary of Repurchase Agreements - Non Trading	30 June 2022 31 December 2021 £m £m Agreements with banks 2,558 4,145 Agreements with customers 4,352 7,573 6,910 11,718

Debt Securities in Issue (Table

Debt Securities in Issue (Tables)	6 Months Ended
	Jun. 30, 2022
Debt Securities In Issue [Abstract]
Summary of Debt Securities in Issue	30 June 2022 31 December 2021 £m £m Medium-term notes 7,972 6,851 Euro 35bn Global Covered Bond Programme 15,952 12,760 US$20bn Commercial Paper Programmes 3,434 2,704 Certificates of deposit 1,667 2,387 Credit linked notes 60 59 Securitisation programmes 436 759 29,521 25,520

Subordinated Liabilities (Table

Subordinated Liabilities (Tables)	6 Months Ended
	Jun. 30, 2022
Subordinated liabilities [abstract]
Schedule of Subordinated Liabilities	30 June 2022 31 December 2021 £m £m 2,335 2,228

Provisions (Tables)

Provisions (Tables)	6 Months Ended
	Jun. 30, 2022
Disclosure of other provisions [abstract]
Summary of Provisions Reconciliation	Customer remediation Litigation and other regulatory Bank Levy Property ECL on undrawn facilities and guarantees Restructuring Other Total £m £m £m £m £m £m £m £m At 1 January 2022 44 166 1 74 38 28 13 364 Additional provisions (See Note 5) 25 16 — 1 10 8 84 144 Provisions released (See Note 5) (12) (1) — — — — — (13) Utilisation and other (8) (15) (1) (11) (2) (12) (83) (132) At 30 June 2022 49 166 — 64 46 24 14 363

Retirement Benefit Plans (Table

Retirement Benefit Plans (Tables)	6 Months Ended
	Jun. 30, 2022
Disclosure of net defined benefit liability (asset) [abstract]
Summary of Retirement Benefit Plans	The amounts recognised in the balance sheet were as follows: 30 June 2022 31 December 2021 £m £m Assets/(liabilities) Funded defined benefit pension scheme - surplus 2,011 1,572 Unfunded pension and post-retirement medical benefits (29) (37) Total net assets 1,982 1,535
Summary of Amounts Recognised in Other Comprehensive Income	The amounts recognised in other comprehensive income were as follows: 30 June 2022 30 June 2021 £m £m Return on plan assets (excluding amounts included in net interest expense) 3,352 383 Actuarial gains arising from experience adjustments 296 (30) Actuarial gains arising from changes in financial assumptions (3,974) (1,098) Pension remeasurement (326) (745)
Summary of Net Assets Recognised	The net assets recognised in the balance sheet were determined as follows: 30 June 2022 31 December 2021 £m £m Present value of defined benefit obligations (9,138) (12,878) Fair value of scheme assets 11,120 14,413 Net defined benefit assets 1,982 1,535
Summary of Principal Actuarial Assumptions Used for Defined Benefit Schemes	The principal actuarial assumptions used for the defined benefit schemes were: 30 June 2022 31 December 2021 % % To determine benefit obligations (1) : – Discount rate for scheme liabilities 3.8 1.9 – General price inflation 3.1 3.4 – General salary increase 1.0 1.0 – Expected rate of pension increase 3.0 3.2 Years Years Longevity at 60 for current pensioners, on the valuation date: – Males 27.5 27.5 – Females 30.2 30.1 Longevity at 60 for future pensioners currently aged 40, on the valuation date: – Males 29.1 29.0 – Females 31.7 31.6 (1) The discount rate and inflation related assumptions set out in the table above reflect the assumptions calculated based on the Scheme’s duration and cash flow profile as a whole. The actual assumptions used were determined for each section independently based on each section’s duration and cash flow profile.
Summary of Actuarial Assumption Sensitivities	The sensitivity analyses below have been determined based on reasonably possible changes of the respective assumptions occurring at the end of the reporting period, while holding all other assumptions constant. (Decrease)/increase Change in pension obligation at period end from 30 June 2022 31 December 2021 Assumption £m £m Discount rate 25 bps increase (335) (571) General price inflation 25 bps increase 239 392 Mortality Each additional year of longevity assumed 256 478

Contingent Liabilities and Co_2

Contingent Liabilities and Commitments (Tables)	6 Months Ended
	Jun. 30, 2022
Disclosure of contingent liabilities [abstract]
Summary of Contingent Liabilities and Commitments	30 June 2022 31 December 2021 £m £m Guarantees given to third parties 428 363 Formal standby facilities, credit lines and other commitments 37,224 37,346 37,652 37,709

Other Equity Instruments (Table

Other Equity Instruments (Tables)	6 Months Ended
	Jun. 30, 2022
Disclosure of classes of share capital [abstract]
Summary of Other Equity Instruments	Interest rate 30 June 2022 31 December 2021 % Next call date £m £m £300m Step-up Callable Perpetual Reserve Capital Instruments 7.037 February 2026 — 235 AT1 securities: - £500m Perpetual Capital Securities 6.75 June 2024 496 496 - £750m Perpetual Capital Securities 7.375 June 2022 — 750 - £500m Perpetual Capital Securities 5.18 n/a — — - £500m Perpetual Capital Securities 6.30 March 2025 500 500 - £210m Perpetual Capital Securities 4.25 March 2026 210 210 - £750m Perpetual Capital Securities 6.50 September 2027 750 — 1,956 2,191

Financial Instruments (Tables)

Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2022
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Abstract]
Disclosure of Analysis of Fair Value of Financial Instruments Carried at Amortised Cost	The following tables analyse the fair value of the financial instruments carried at amortised cost at 30 June 2022 and 31 December 2021. It does not include fair value information for financial assets and financial liabilities carried at amortised cost if the carrying amount is a reasonable approximation of fair value. Details of the valuation methodology of the financial assets and financial liabilities carried at amortised cost can be found in Note 40(e) to the Consolidated Financial Statements in the 2021 Annual Report. 30 June 2022 31 December 2021 Fair value Carrying Fair value Carrying Level 1 Level 2 Level 3 Fair value value Level 1 Level 2 Level 3 Fair value value £m £m £m £m £m £m £m £m £m £m Assets Loans and advances to customers — — 215,234 215,234 217,012 — — 212,811 212,811 210,094 Loans and advances to banks — 793 — 793 793 — 1,169 — 1,169 1,169 Reverse repurchase agreements - non trading — 8,785 — 8,785 8,793 — 12,453 226 12,679 12,683 Other financial assets at amortised cost 151 — — 151 156 164 348 — 512 506 151 9,578 215,234 224,963 226,754 164 13,970 213,037 227,171 224,452 Liabilities Deposits by customers — 210 189,516 189,726 189,729 — 48 192,898 192,946 192,926 Deposits by banks — 35,012 63 35,075 35,182 — 33,770 85 33,855 33,855 Repurchase agreements - non trading — 6,910 — 6,910 6,910 — 11,718 — 11,718 11,718 Debt securities in issue 2,349 22,569 4,622 29,540 29,521 963 23,926 1,218 26,107 25,520 Subordinated liabilities 19 2,610 — 2,629 2,335 37 2,350 238 2,625 2,228 2,368 67,311 194,201 263,880 263,677 1,000 71,812 194,439 267,251 266,247
Disclosure of Analysis of Fair Value of Financial Instruments Measured at Fair Value on a Recurring Basis	The following tables summarise the fair values of the financial assets and liabilities accounted for at fair value at 30 June 2022 and 31 December 2021, analysed by their levels in the fair value hierarchy - Level 1, Level 2 and Level 3. 30 June 2022 31 December 2021 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Valuation £m £m £m £m £m £m £m £m technique Assets Derivative financial instruments Exchange rate contracts — 1,909 — 1,909 — 1,193 1 1,194 A Interest rate contracts — 2,002 2 2,004 — 1,547 — 1,547 A & C Equity and credit contracts — 102 39 141 — 116 45 161 B & D Netting — (1,783) — (1,783) — (1,221) — (1,221) — 2,230 41 2,271 — 1,635 46 1,681 Other financial assets at FVTPL Loans and advances to customers — — 60 60 — — 74 74 A Debt securities — — 95 95 — — 111 111 A, B & D — — 155 155 — — 185 185 Financial assets at FVOCI Debt securities 4,894 — — 4,894 5,833 — — 5,833 D Loans and advances to customers — — 19 19 — — 18 18 D 4,894 — 19 4,913 5,833 — 18 5,851 Total assets at fair value 4,894 2,230 215 7,339 5,833 1,635 249 7,717 Liabilities Derivative financial instruments Exchange rate contracts — 427 — 427 — 506 — 506 A Interest rate contracts — 2,038 3 2,041 — 1,436 2 1,438 A & C Equity and credit contracts — 22 13 35 — 24 30 54 B & D Netting — (1,783) — (1,783) — (1,221) — (1,221) — 704 16 720 — 745 32 777 Other financial liabilities at FVTPL Debt securities in issue — 463 3 466 — 555 5 560 A Structured deposits — 346 — 346 — 223 — 223 A Collateral and associated financial guarantees — 15 — 15 — 19 1 20 D — 824 3 827 — 797 6 803 Total liabilities at fair value — 1,528 19 1,547 — 1,542 38 1,580
Summary of Fair Value Adjustment	The magnitude and types of fair value adjustment are listed in the following table: 30 June 2022 31 December 2021 £m £m Risk-related: - Bid-offer and trade specific adjustments (15) (9) - Uncertainty 15 20 - Credit risk adjustment 6 6 - Funding fair value adjustment 4 3 10 20
Summary of Reconciliation of Fair Value Measurement in Level 3 of the Fair Value Hierarchy	The following table sets out the movements in Level 3 financial instruments in H122: Assets Liabilities Derivatives Other financial assets at FVTPL Financial assets at FVOCI Total Derivatives Other financial liabilities at FVTPL Total £m £m £m £m £m £m £m At 1 January 2022 46 185 18 249 (32) (6) (38) Total (losses)/gains recognised: Fair value movements (2) (2) (18) 1 (19) — 5 5 Transfers in — — — — (2) — (2) Netting (1) — — — — — (4) (4) Settlements (3) (12) — (15) 18 2 20 At 30 June 2022 41 155 19 215 (16) (3) (19) Gains/(losses) recognised in profit or loss/other comprehensive income relating to assets and liabilities held at the end of the period (2) (2) (18) 1 (19) — 5 5 (1) This relates to the effect of netting on the fair value of the credit linked notes due to a legal right of set-off between the principal amounts of the senior notes and the associated cash deposits. For more, see ‘ii) Credit protection entities’ in Note 19 to the Consolidated Financial Statements in the 2021 Annual Report.

Interest Rate Benchmark Reform

Interest Rate Benchmark Reform (Tables)	6 Months Ended
	Jun. 30, 2022
Interest Rate Benchmark Reform [Abstract]
Schedule of Amounts Affected by IBOR Reform	The following tables show the notional amounts of assets, liabilities and off-balance sheet commitments at 30 June 2022 and 31 December 2021 affected by IBOR reform that have yet to transition to an alternative benchmark interest rate as provided internally to key management personnel. 30 June 2022 GBP (2) LIBOR USD (2) LIBOR Other (2) Total £m £m £m £m Assets Derivatives (1) — 1,650 — 1,650 Financial assets at amortised cost 85 17 — 102 85 1,667 — 1,752 Liabilities Derivatives (1) 130 1,830 — 1,960 Other financial liabilities at fair value through profit and loss — 3 — 3 130 1,833 — 1,963 Off-balance sheet commitments given 8 79 — 87 31 December 2021 GBP (2) LIBOR USD (2) LIBOR Other (2) Total £m £m £m £m Assets Derivatives (1) — 1,480 — 1,480 Other financial assets at fair value through profit and loss 8 — — 8 Financial assets at amortised cost 1,373 81 1 1,455 1,381 1,561 1 2,943 Liabilities Derivatives (1) 338 1,831 — 2,169 Other financial liabilities at fair value through profit and loss — 5 — 5 Financial liabilities at amortised cost 34 185 — 219 372 2,021 — 2,393 Off-balance sheet commitments given 338 59 — 397 (1) Many of the Santander UK group's derivatives subject to IBOR reform are standard ISDA contracts and are subject to supplementary ISDA fallback provisions which became effective on 25 January 2021 setting out what floating rates apply on the permanent discontinuation of key IBORs. The Santander UK group adhered to the protocol and implemented the fallback provisions to derivative contracts entered into before 25 January 2021. Where derivative counterparties also adhered to the protocol, fallback provisions were automatically implemented in existing derivative contracts when the supplement became effective. 1-month, 3-month and 6-month GBP & JPY settings for certain legacy contracts have been extended until at least the end of 2022 but not for cleared derivative contracts. (2) Settings for GBP, JPY & NOK LIBOR & 1-week and 2-month USD LIBOR ceased on 31 December 2021 and for EONIA on 3 January 2022, however, for certain legacy contracts, 1-month, 3-month and 6-month settings for GBP & JPY LIBOR have been extended until at least 31 December 2022. Remaining USD LIBOR settings (overnight, 1-month, 3-month, 6-month and 12-month) will cease on 30 June 2023.
Schedule of Derivatives Directly Affected by IBOR Reform Uncertainties	The table below shows the notional amount of derivatives in hedging relationships directly affected by uncertainties related to IBOR reform. 30 June 2022 31 December 2021 GBP USD Other Total GBP USD Other Total £m £m £m £m £m £m £m £m Total notional value of hedging instruments – Cash flow hedges — 2,881 — 2,881 — 2,586 — 2,586 – Fair value hedges — 176 — 176 — 160 — 160 — 3,057 — 3,057 — 2,746 — 2,746 Maturing after cessation date (1) – Cash flow hedges — 2,881 — 2,881 — 2,586 — 2,586 – Fair value hedges — 176 — 176 — 160 — 160 — 3,057 — 3,057 — 2,746 — 2,746 (1) Settings for GBP, JPY & NOK LIBOR & 1-week and 2-month USD LIBOR ceased on 31 December 2021 and for EONIA on 3 January 2022, however, for certain legacy contracts, 1-month, 3-month and 6-month settings for GBP & JPY LIBOR have been extended until at least 31 December 2022. Remaining USD LIBOR settings (overnight, 1-month, 3-month, 6-month and 12-month) will cease on 30 June 2023.

Discontinued Operations and A_2

Discontinued Operations and Assets Held for Sale (Tables)	6 Months Ended
	Jun. 30, 2022
Discontinued Operations and Assets and Liabilities Held for Sale [Abstract]
Disclosure of Financial Performance Relating to Discontinued Operations	For the periods prior to its sale, the Corporate & Investment Banking business met the requirements for presentation as discontinued operations. The financial performance and cash flow information relating to the discontinued operations were as follows: For the Half Year to 30 June 2022 30 June 2021 £m £m Net interest income — 24 Net fee and commission income — 27 Total operating income — 51 Operating expenses before credit impairment losses, provisions and charges — (22) Credit impairment losses — 7 Provisions for other liabilities and charges — (3) Total operating credit impairment losses, provisions and charges — 4 Profit from discontinued operations before tax — 33 Tax on profit from discontinued operations — (9) Profit from discontinued operations after tax — 24
Disclosure of Assets Classified as Held for Sale	At 30 June 2022, assets held for sale comprised: £m Assets Property, plant and equipment 49 Total assets held for sale 49

Segments (Details)

Segments (Details) - GBP (£) £ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Disclosure of operating segments [line items]
Net interest income	£ 2,120	£ 1,905
Non-interest income	270	286
Total operating income	2,390	2,191
Operating expenses before credit impairment (losses)/write-backs, provisions and charges	(1,172)	(1,328)
Credit impairment (losses)/write-backs	(118)	70
Provisions for other liabilities and charges	(118)	(190)
Total operating credit impairment (losses)/write-backs, provisions and charges	(236)	(120)
Profit from continuing operations before tax	982	743
Revenue from external customers	2,390	2,191
Inter-segment revenue	2,390	2,191
Revenue from external customers includes the following fee and commission income disaggregated by income type
Current account and debit card fees	247	195
Insurance, protection and investments	31	32
Credit cards	46	37
Non-banking and other fees	53	41
Total fee and commission income	377	305
Fee and commission expense	(209)	(154)
Net fee and commission income	168	151
Customer loans	213,516		£ 207,288
Total assets	284,317		287,098
Assets held for sale	49		0
Customer deposits	184,004		186,215
Total liabilities	268,644		270,996
Inter-segment revenue
Disclosure of operating segments [line items]
Inter-segment revenue	0	0
Retail Banking
Disclosure of operating segments [line items]
Net interest income	1,784	1,602
Non-interest income	116	109
Total operating income	1,900	1,711
Operating expenses before credit impairment (losses)/write-backs, provisions and charges	(831)	(858)
Credit impairment (losses)/write-backs	(126)	28
Provisions for other liabilities and charges	(101)	(67)
Total operating credit impairment (losses)/write-backs, provisions and charges	(227)	(39)
Profit from continuing operations before tax	842	814
Revenue from external customers	2,033	1,939
Revenue from external customers includes the following fee and commission income disaggregated by income type
Current account and debit card fees	218	172
Insurance, protection and investments	31	32
Credit cards	46	37
Non-banking and other fees	4	1
Total fee and commission income	299	242
Fee and commission expense	(191)	(136)
Net fee and commission income	108	106
Customer loans	189,318		183,023
Total assets	196,505		190,629
Assets held for sale	0
Customer deposits	154,759		156,991
Total liabilities	155,199		157,622
Retail Banking | Inter-segment revenue
Disclosure of operating segments [line items]
Inter-segment revenue	(133)	(228)
Consumer Finance
Disclosure of operating segments [line items]
Net interest income	92	135
Non-interest income	101	77
Total operating income	193	212
Operating expenses before credit impairment (losses)/write-backs, provisions and charges	(73)	(90)
Credit impairment (losses)/write-backs	(13)	20
Provisions for other liabilities and charges	0	0
Total operating credit impairment (losses)/write-backs, provisions and charges	(13)	20
Profit from continuing operations before tax	107	142
Revenue from external customers	243	255
Revenue from external customers includes the following fee and commission income disaggregated by income type
Current account and debit card fees	0	0
Insurance, protection and investments	0	0
Credit cards	0	0
Non-banking and other fees	8	4
Total fee and commission income	8	4
Fee and commission expense	0	0
Net fee and commission income	8	4
Customer loans	5,129		4,984
Total assets	9,652		8,873
Assets held for sale	0
Customer deposits	0		0
Total liabilities	1,153		1,173
Consumer Finance | Inter-segment revenue
Disclosure of operating segments [line items]
Inter-segment revenue	(50)	(43)
Corporate & Commercial Banking
Disclosure of operating segments [line items]
Net interest income	242	202
Non-interest income	69	51
Total operating income	311	253
Operating expenses before credit impairment (losses)/write-backs, provisions and charges	(181)	(181)
Credit impairment (losses)/write-backs	19	23
Provisions for other liabilities and charges	(2)	(5)
Total operating credit impairment (losses)/write-backs, provisions and charges	17	18
Profit from continuing operations before tax	147	90
Revenue from external customers	318	272
Revenue from external customers includes the following fee and commission income disaggregated by income type
Current account and debit card fees	29	23
Insurance, protection and investments	0	0
Credit cards	0	0
Non-banking and other fees	36	29
Total fee and commission income	65	52
Fee and commission expense	(11)	(10)
Net fee and commission income	54	42
Customer loans	17,358		16,997
Total assets	17,358		16,997
Assets held for sale	0
Customer deposits	25,305		25,597
Total liabilities	25,326		25,613
Corporate & Commercial Banking | Inter-segment revenue
Disclosure of operating segments [line items]
Inter-segment revenue	(7)	(19)
Corporate & Investment Banking
Disclosure of operating segments [line items]
Net interest income		0
Non-interest income		0
Total operating income		0
Operating expenses before credit impairment (losses)/write-backs, provisions and charges		0
Credit impairment (losses)/write-backs		0
Provisions for other liabilities and charges		0
Total operating credit impairment (losses)/write-backs, provisions and charges		0
Profit from continuing operations before tax		0
Revenue from external customers		0
Revenue from external customers includes the following fee and commission income disaggregated by income type
Current account and debit card fees		0
Insurance, protection and investments		0
Credit cards		0
Non-banking and other fees		0
Total fee and commission income		0
Fee and commission expense		0
Net fee and commission income		0
Customer loans			0
Total assets			0
Customer deposits			0
Total liabilities			0
Corporate & Investment Banking | Inter-segment revenue
Disclosure of operating segments [line items]
Inter-segment revenue		0
Corporate Centre
Disclosure of operating segments [line items]
Net interest income	2	(34)
Non-interest income	(16)	49
Total operating income	(14)	15
Operating expenses before credit impairment (losses)/write-backs, provisions and charges	(87)	(199)
Credit impairment (losses)/write-backs	2	(1)
Provisions for other liabilities and charges	(15)	(118)
Total operating credit impairment (losses)/write-backs, provisions and charges	(13)	(119)
Profit from continuing operations before tax	(114)	(303)
Revenue from external customers	(204)	(275)
Revenue from external customers includes the following fee and commission income disaggregated by income type
Current account and debit card fees	0	0
Insurance, protection and investments	0	0
Credit cards	0	0
Non-banking and other fees	5	7
Total fee and commission income	5	7
Fee and commission expense	(7)	(8)
Net fee and commission income	(2)	(1)
Customer loans	1,711		2,284
Total assets	60,802		70,599
Assets held for sale	49
Customer deposits	3,940		3,627
Total liabilities	86,966		£ 86,588
Corporate Centre | Inter-segment revenue
Disclosure of operating segments [line items]
Inter-segment revenue	£ 190	£ 290

Other Operating Income (Details

Other Operating Income (Details) - GBP (£) £ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Net Trading And Other Income [abstract]
Loss on repurchase of debt securities and subordinated liabilities	£ 1
Loss on repurchase of debt securities		£ 27

Operating Expenses Before Cre_3

Operating Expenses Before Credit Impairment Losses, Provisions and Charges - Summary of Operating Expenses Before Credit Impairment Losses, Provisions and Charges (Details) - GBP (£) £ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Expenses by nature [abstract]
Staff costs	£ 556	£ 577
Other administration expenses	458	431
Depreciation, amortisation and impairment	158	320
Total operating expenses before impairment losses, provisions and charges	£ 1,172	£ 1,328

Operating Expenses Before Cre_4

Operating Expenses Before Credit Impairment Losses, Provisions and Charges - Additional Information (Details) - Accumulated depreciation - GBP (£) £ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Operating Expenses Before Credit Impairment Losses Provision And Charges [Line Items]
Impairment during the period	£ (10)
Branch and head office site closures
Operating Expenses Before Credit Impairment Losses Provision And Charges [Line Items]
Impairment during the period	£ 10	£ 105

Credit Impairment Losses and _3

Credit Impairment Losses and Provisions - Summary of Impairment Losses and Provisions (Details) - GBP (£) £ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Disclosure Of Credit Impairment Loss And Provisions [Abstract]
Loans and advances to customers	£ 114	£ (33)
Recoveries of loans and advances, net of collection costs	(6)	(13)
Off-balance sheet exposures (See Note 24)	10	(24)
Impairment loss on financial assets	118	(70)
Provisions for other liabilities and charges (excluding off-balance sheet credit exposures) (See Note 24)	121	191
Releases for residual value and voluntary termination	(3)	(1)
Provisions for other liabilities and charges	118	190
Total operating credit impairment loss/(release), provisions and charges	£ 236	£ 120

Credit Impairment Losses and _4

Credit Impairment Losses and Provisions - Additional Information (Details) - GBP (£) £ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Disclosure Of Credit Impairment Loss And Provisions [Abstract]
Impairment losses on loans and advances to banks	£ 0	£ 0
Impairment losses on non-trading reverse repurchase agreements	0	0
Impairment losses on other financial assets at amortised cost	0	0
Impairment losses on financial assets at FVOCI	£ 0	£ 0

Taxation - Additional Informati

Taxation - Additional Information (Details)	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Income Tax Expense Benefits [Line Items]
Effective tax rate (percentage)	23.60%	27.60%
Forecast
Income Tax Expense Benefits [Line Items]
Effective tax rate (percentage)	26%	25.80%

Taxation - Schedule of Tax on P

Taxation - Schedule of Tax on Profit Before Tax Differs from Theoretical Amount that Arise Using Basic Corporation Tax Rate (Details) - GBP (£) £ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Major components of tax expense (income) [abstract]
Profit from continuing operations before tax	£ 982	£ 743
Tax calculated at a tax rate of 19% (H121: 19%)	187	141
Bank surcharge on profits	70	49
Non-deductible preference dividends paid	5	6
Non-deductible UK Bank Levy	8	14
Non-deductible conduct remediation, fines and penalties	(1)	0
Other non-deductible costs and non-taxable income	8	14
Effect of change in tax rate on deferred tax provision	(23)	13
Tax relief on dividends in respect of other equity instruments	(22)	(32)
Tax on profit from continuing operations	£ 232	£ 205

Dividends on Ordinary Shares (D

Dividends on Ordinary Shares (Details) - GBP (£) £ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Dividends On Ordinary Shares [Abstract]
Dividends declared and paid	£ 389	£ 0

Derivative Financial Instrume_3

Derivative Financial Instruments (Details) - GBP (£) £ in Millions	Jun. 30, 2022	Dec. 31, 2021
Disclosure of detailed information about hedges
Notional amount	£ 177,637	£ 162,049
Assets	2,271	1,681
Liabilities	720	777
Derivatives held for trading:
Disclosure of detailed information about hedges
Notional amount	44,080	37,240
Derivatives held for hedging
Disclosure of detailed information about hedges
Notional amount	133,557	124,809
Fair value hedges | Derivatives held for hedging
Disclosure of detailed information about hedges
Notional amount	83,560	81,104
Cash flow hedges | Derivatives held for hedging
Disclosure of detailed information about hedges
Notional amount	49,997	43,705
Exchange rate contracts | Derivatives held for trading:
Disclosure of detailed information about hedges
Notional amount	13,712	11,036
Exchange rate contracts | Fair value hedges | Derivatives held for hedging
Disclosure of detailed information about hedges
Notional amount	490	590
Exchange rate contracts | Cash flow hedges | Derivatives held for hedging
Disclosure of detailed information about hedges
Notional amount	24,636	22,239
Interest rate contracts | Derivatives held for trading:
Disclosure of detailed information about hedges
Notional amount	29,363	25,148
Interest rate contracts | Fair value hedges | Derivatives held for hedging
Disclosure of detailed information about hedges
Notional amount	83,070	80,514
Interest rate contracts | Cash flow hedges | Derivatives held for hedging
Disclosure of detailed information about hedges
Notional amount	25,361	21,466
Equity and credit contracts | Derivatives held for trading:
Disclosure of detailed information about hedges
Notional amount	1,005	1,056
Derivative assets
Disclosure of detailed information about hedges
Cash collateral received subject to enforceable master netting arrangement or similar agreement not set off against financial assets	557	189
Derivative liabilities
Disclosure of detailed information about hedges
Collateral cash	557	202
Fair value
Disclosure of detailed information about hedges
Assets	2,271	1,681
Liabilities	720	777
Fair value | Derivatives held for trading:
Disclosure of detailed information about hedges
Assets	832	783
Liabilities	951	707
Fair value | Derivatives held for hedging
Disclosure of detailed information about hedges
Assets	3,222	2,119
Liabilities	1,552	1,291
Fair value | Fair value hedges | Derivatives held for hedging
Disclosure of detailed information about hedges
Assets	1,397	943
Liabilities	449	737
Fair value | Cash flow hedges | Derivatives held for hedging
Disclosure of detailed information about hedges
Assets	1,825	1,176
Liabilities	1,103	554
Fair value | Exchange rate contracts | Derivatives held for trading:
Disclosure of detailed information about hedges
Assets	287	159
Liabilities	314	168
Fair value | Exchange rate contracts | Fair value hedges | Derivatives held for hedging
Disclosure of detailed information about hedges
Assets	20	39
Liabilities	2	0
Fair value | Exchange rate contracts | Cash flow hedges | Derivatives held for hedging
Disclosure of detailed information about hedges
Assets	1,602	996
Liabilities	111	338
Fair value | Interest rate contracts | Derivatives held for trading:
Disclosure of detailed information about hedges
Assets	404	463
Liabilities	602	485
Fair value | Interest rate contracts | Fair value hedges | Derivatives held for hedging
Disclosure of detailed information about hedges
Assets	1,377	904
Liabilities	447	737
Fair value | Interest rate contracts | Cash flow hedges | Derivatives held for hedging
Disclosure of detailed information about hedges
Assets	223	180
Liabilities	992	216
Fair value | Equity and credit contracts | Derivatives held for trading:
Disclosure of detailed information about hedges
Assets	141	161
Liabilities	35	54
Fair value | Derivative netting
Disclosure of detailed information about hedges
Assets	(1,783)	(1,221)
Liabilities	£ (1,783)	£ (1,221)

Other Financial Assets at Fai_3

Other Financial Assets at Fair Value Through Profit or Loss (Details) - GBP (£) £ in Millions	Jun. 30, 2022	Dec. 31, 2021
Disclosure Of Other Financial Assets At Fair Value Through Profit Or Loss [Line Items]
Financial assets at fair value through profit or loss	£ 155	£ 185
Loans and advances to customers
Disclosure Of Other Financial Assets At Fair Value Through Profit Or Loss [Line Items]
Financial assets at fair value through profit or loss	60	74
Debt securities
Disclosure Of Other Financial Assets At Fair Value Through Profit Or Loss [Line Items]
Financial assets at fair value through profit or loss	95	111
Loans to housing associations | Loans and advances to customers
Disclosure Of Other Financial Assets At Fair Value Through Profit Or Loss [Line Items]
Financial assets at fair value through profit or loss	11	12
Other loans | Loans and advances to customers
Disclosure Of Other Financial Assets At Fair Value Through Profit Or Loss [Line Items]
Financial assets at fair value through profit or loss	£ 49	£ 62

Loans and Advances to Custome_3

Loans and Advances to Customers (Details) - GBP (£) £ in Millions	Jun. 30, 2022	Dec. 31, 2021
Net Loans And Advances To Customers [Abstract]
Loans and advances to customers	£ 217,910	£ 210,947
Credit impairment loss allowances on loans and advances to customers	(876)	(828)
Residual value and voluntary termination provisions on finance leases	(22)	(25)
Net loans and advances to customers	£ 217,012	£ 210,094

Securitisations and Covered B_3

Securitisations and Covered Bonds - Disclosure of Analysis of Securitisations and Covered Bonds (Details) - GBP (£) £ in Millions	Jun. 30, 2022	Dec. 31, 2021
Disclosure Of Securitisations And Covered Bonds [Line Items]
Gross assets	£ 24,183	£ 20,199
Securitisation programmes
Disclosure Of Securitisations And Covered Bonds [Line Items]
Gross assets	3,938	4,486
Securitisation programmes | Mortgage-backed master trust structures:
Disclosure Of Securitisations And Covered Bonds [Line Items]
Gross assets	3,920	4,448
Securitisation programmes | Other asset-backed securitisation structures:
Disclosure Of Securitisations And Covered Bonds [Line Items]
Gross assets	18	38
Holmes | Securitisation programmes | Mortgage-backed master trust structures:
Disclosure Of Securitisations And Covered Bonds [Line Items]
Gross assets	2,010	2,294
Fosse | Securitisation programmes | Mortgage-backed master trust structures:
Disclosure Of Securitisations And Covered Bonds [Line Items]
Gross assets	1,910	2,154
Motor | Securitisation programmes | Other asset-backed securitisation structures:
Disclosure Of Securitisations And Covered Bonds [Line Items]
Gross assets	18	38
Euro 35bn Global Covered Bond Programme | Covered bond programmes
Disclosure Of Securitisations And Covered Bonds [Line Items]
Gross assets	£ 20,245	£ 15,713

Securitisations and Covered B_4

Securitisations and Covered Bonds - Summary of Issuances and Redemptions of Securitisation and Covered Bond Programme (Details) - GBP (£) £ in Billions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Internal issuances
Issuances And Redemptions Of Securitisation And Covered Bond [Line items]
Internal and external issuances	£ 0	£ 0
Internal and external redemptions	0	2.6
Internal issuances | Mortgage-backed master trust structures: | Holmes
Issuances And Redemptions Of Securitisation And Covered Bond [Line items]
Internal and external issuances	0	0
Internal and external redemptions	0	0
Internal issuances | Mortgage-backed master trust structures: | Langton
Issuances And Redemptions Of Securitisation And Covered Bond [Line items]
Internal and external issuances	0	0
Internal and external redemptions	0	2.4
Internal issuances | Other asset-backed securitisation structures: | Motor
Issuances And Redemptions Of Securitisation And Covered Bond [Line items]
Internal and external issuances	0	0
Internal and external redemptions	0	0.1
Internal issuances | Other asset-backed securitisation structures: | Auto ABS UK Loans
Issuances And Redemptions Of Securitisation And Covered Bond [Line items]
Internal and external issuances	0	0
Internal and external redemptions	0	0.1
Internal issuances | Covered bond programmes
Issuances And Redemptions Of Securitisation And Covered Bond [Line items]
Internal and external issuances	0	0
Internal and external redemptions	0	0
External issuances
Issuances And Redemptions Of Securitisation And Covered Bond [Line items]
Internal and external issuances	0	0
Internal and external redemptions	0	4.9
External issuances | Mortgage-backed master trust structures: | Holmes
Issuances And Redemptions Of Securitisation And Covered Bond [Line items]
Internal and external issuances	0	0
Internal and external redemptions	0	0.3
External issuances | Mortgage-backed master trust structures: | Langton
Issuances And Redemptions Of Securitisation And Covered Bond [Line items]
Internal and external issuances	0	0
Internal and external redemptions	0	0
External issuances | Other asset-backed securitisation structures: | Motor
Issuances And Redemptions Of Securitisation And Covered Bond [Line items]
Internal and external issuances	0	0
Internal and external redemptions	0	0
External issuances | Other asset-backed securitisation structures: | Auto ABS UK Loans
Issuances And Redemptions Of Securitisation And Covered Bond [Line items]
Internal and external issuances	0	0
Internal and external redemptions	0	0.1
External issuances | Covered bond programmes
Issuances And Redemptions Of Securitisation And Covered Bond [Line items]
Internal and external issuances	0	0
Internal and external redemptions	£ 0	£ 4.5

Securitisations and Covered B_5

Securitisations and Covered Bonds - Additional Information (Details) - GBP (£) £ in Millions	6 Months Ended
	Jun. 30, 2021	Jul. 30, 2021
PSA Finance UK Limited | Santander Consumer (UK)
Disclosure Of Securitisations And Covered Bonds [Line Items]
Proportion of ownership interest in subsidiary sold		50%
Langton
Disclosure Of Securitisations And Covered Bonds [Line Items]
Gain or loss on covered bonds programme redemption	£ 0

Reverse Repurchase Agreements_3

Reverse Repurchase Agreements - Non Trading (Details) - GBP (£) £ in Millions	Jun. 30, 2022	Dec. 31, 2021
Disclosure Of Reserve Repurchase Agreements Non-Trading [Line Items]
Repurchase agreements – non trading	£ 8,793	£ 12,683
Agreements with banks
Disclosure Of Reserve Repurchase Agreements Non-Trading [Line Items]
Repurchase agreements – non trading	475	447
Agreements with customers
Disclosure Of Reserve Repurchase Agreements Non-Trading [Line Items]
Repurchase agreements – non trading	£ 8,318	£ 12,236

Other Financial Assets at Amo_3

Other Financial Assets at Amortised Cost (Details) - Other financial assets - GBP (£) £ in Millions	Jun. 30, 2022	Dec. 31, 2021
Financial Assets At Fair Value Through Profit Or Loss [Line Items]
Financial assets at amortised cost	£ 156	£ 506
Asset backed securities
Financial Assets At Fair Value Through Profit Or Loss [Line Items]
Financial assets at amortised cost	94	443
Debt securities
Financial Assets At Fair Value Through Profit Or Loss [Line Items]
Financial assets at amortised cost	£ 62	£ 63

Financial Assets at Fair Valu_3

Financial Assets at Fair Value Through Other Comprehensive Income (Details) - GBP (£) £ in Millions	Jun. 30, 2022	Dec. 31, 2021
Disclosure Of Financial Assets At Fair Value Through Other Comprehensive Income [Line Items]
Financial assets at FVOCI	£ 4,913	£ 5,851
Debt securities
Disclosure Of Financial Assets At Fair Value Through Other Comprehensive Income [Line Items]
Financial assets at FVOCI	4,894	5,833
Loans and advances to customers
Disclosure Of Financial Assets At Fair Value Through Other Comprehensive Income [Line Items]
Financial assets at FVOCI	£ 19	£ 18

Intangible Assets (Details)

Intangible Assets (Details) - GBP (£) £ in Millions	Jun. 30, 2022	Jun. 30, 2021
Disclosure of detailed information about intangible assets [line items]
Goodwill	£ 1,199	£ 1,203
Computer software
Disclosure of detailed information about intangible assets [line items]
Intangible assets other than goodwill	£ 339	£ 342

Property, Plant and Equipment_2

Property, Plant and Equipment (Details) - GBP (£) £ in Millions	6 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	£ 1,548
Property, plant and equipment at end of period	1,490
Construction in progress	155	£ 106
Investment property	20	£ 17
Cost
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	3,470
Additions	204
Reclassification to assets held for sale	(140)
Disposals	(805)
Property, plant and equipment at end of period	2,729
Accumulated depreciation
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	(1,922)
Additions	(94)
Impairment during the period	10
Reclassification to assets held for sale	91
Disposals	696
Property, plant and equipment at end of period	(1,239)
Property
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at end of period	601
Property | Cost
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	978
Additions	31
Reclassification to assets held for sale	(109)
Disposals	(25)
Property, plant and equipment at end of period	875
Property | Accumulated depreciation
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	(334)
Additions	(10)
Impairment during the period	8
Reclassification to assets held for sale	62
Disposals	16
Property, plant and equipment at end of period	(274)
Office fixtures and equipment
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at end of period	180
Office fixtures and equipment | Cost
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	1,049
Additions	29
Reclassification to assets held for sale	(31)
Disposals	(268)
Property, plant and equipment at end of period	779
Office fixtures and equipment | Accumulated depreciation
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	(857)
Additions	(34)
Impairment during the period	2
Reclassification to assets held for sale	29
Disposals	265
Property, plant and equipment at end of period	(599)
Computer software
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at end of period	0
Computer software | Cost
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	434
Additions	0
Reclassification to assets held for sale	0
Disposals	(363)
Property, plant and equipment at end of period	71
Computer software | Accumulated depreciation
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	(434)
Additions	0
Impairment during the period	0
Reclassification to assets held for sale	0
Disposals	363
Property, plant and equipment at end of period	(71)
Operating lease assets
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at end of period	591
Operating lease assets | Cost
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	755
Additions	112
Reclassification to assets held for sale	0
Disposals	(126)
Property, plant and equipment at end of period	741
Operating lease assets | Accumulated depreciation
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	(160)
Additions	(41)
Impairment during the period	0
Reclassification to assets held for sale	0
Disposals	51
Property, plant and equipment at end of period	(150)
Right-of-use assets
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at end of period	118
Right-of-use assets | Cost
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	254
Additions	32
Reclassification to assets held for sale	0
Disposals	(23)
Property, plant and equipment at end of period	263
Right-of-use assets | Accumulated depreciation
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	(137)
Additions	(9)
Impairment during the period	0
Reclassification to assets held for sale	0
Disposals	1
Property, plant and equipment at end of period	£ (145)

Other Financial Liabilities a_3

Other Financial Liabilities at Fair Value Through Profit or Loss (Details) £ in Millions	Jun. 30, 2022 GBP (£)	Jun. 30, 2022 USD ($)	Dec. 31, 2021 GBP (£)	Dec. 31, 2021 USD ($)
Disclosure Of Other Financial Liabilities At Fair Value Through Profit Or Loss [Line Items]
Other financial liabilities at fair value through profit or loss	£ 827		£ 803
Notional amount	177,637		162,049
US$30bn Euro Medium Term Note Programme
Disclosure Of Other Financial Liabilities At Fair Value Through Profit Or Loss [Line Items]
Other financial liabilities at fair value through profit or loss	3		5
Notional amount | $		$ 30,000,000,000		$ 30,000,000,000
Structured Notes Programmes
Disclosure Of Other Financial Liabilities At Fair Value Through Profit Or Loss [Line Items]
Other financial liabilities at fair value through profit or loss	353		413
Eurobonds
Disclosure Of Other Financial Liabilities At Fair Value Through Profit Or Loss [Line Items]
Other financial liabilities at fair value through profit or loss	110		142
Structured deposits
Disclosure Of Other Financial Liabilities At Fair Value Through Profit Or Loss [Line Items]
Other financial liabilities at fair value through profit or loss	346		223
Collateral and associated financial guarantees
Disclosure Of Other Financial Liabilities At Fair Value Through Profit Or Loss [Line Items]
Other financial liabilities at fair value through profit or loss	£ 15		£ 20

Deposits by Customers (Details)

Deposits by Customers (Details) - GBP (£) £ in Millions	Jun. 30, 2022	Dec. 31, 2021
Disclosure Of Deposits From Customers [Line Items]
Deposits by customers	£ 189,729	£ 192,926
Demand and time deposits
Disclosure Of Deposits From Customers [Line Items]
Deposits by customers	183,553	185,843
Amounts due to other Santander UK Group Holdings plc subsidiaries
Disclosure Of Deposits From Customers [Line Items]
Deposits by customers	63	59
Amounts due to Santander UK Group Holdings plc
Disclosure Of Deposits From Customers [Line Items]
Deposits by customers	4,987	5,874
Amounts due to fellow Banco Santander subsidiaries and joint ventures
Disclosure Of Deposits From Customers [Line Items]
Deposits by customers	1,126	1,150
Equity Index Linked Deposits
Disclosure Of Deposits From Customers [Line Items]
Deposits by customers	520	549
Capital amount guaranteed or protected	520	549
Capital amount of return guaranteed	£ 2	£ 2

Deposits by Banks (Details)

Deposits by Banks (Details) - GBP (£) £ in Millions	Jun. 30, 2022	Dec. 31, 2021
Disclosure Of Deposits From Banks [Line Items]
Deposits by banks	£ 35,182	£ 33,855
Drawdown from TFS	0	0
Drawdown from TFSME	31,900	31,900
Items in the course of transmission
Disclosure Of Deposits From Banks [Line Items]
Deposits by banks	447	414
Deposits held as collateral
Disclosure Of Deposits From Banks [Line Items]
Deposits by banks	1,627	931
Other deposits
Disclosure Of Deposits From Banks [Line Items]
Deposits by banks	33,105	32,507
Amounts due to Santander UK subsidiaries
Disclosure Of Deposits From Banks [Line Items]
Deposits by banks	£ 3	£ 3

Repurchase Agreements - Non T_3

Repurchase Agreements - Non Trading (Details) - GBP (£) £ in Millions	Jun. 30, 2022	Dec. 31, 2021
Disclosure Of Repurchase Agreements [Line Items]
Repurchase agreements - non trading	£ 6,910	£ 11,718
Agreements with banks
Disclosure Of Repurchase Agreements [Line Items]
Repurchase agreements - non trading	2,558	4,145
Agreements with customers
Disclosure Of Repurchase Agreements [Line Items]
Repurchase agreements - non trading	£ 4,352	£ 7,573

Debt Securities in Issue (Detai

Debt Securities in Issue (Details) £ in Millions	Jun. 30, 2022 GBP (£)	Jun. 30, 2022 EUR (€)	Jun. 30, 2022 USD ($)	Dec. 31, 2021 GBP (£)	Dec. 31, 2021 EUR (€)	Dec. 31, 2021 USD ($)
Debt Securities In Issue [Line Items]
Notional amount	£ 177,637			£ 162,049
Debt securities	29,521			25,520
Medium-term notes
Debt Securities In Issue [Line Items]
Debt securities	7,972			6,851
Euro 35bn Global Covered Bond Programme
Debt Securities In Issue [Line Items]
Notional amount | €		€ 35,000,000,000			€ 35,000,000,000
Debt securities	15,952			12,760
US$20bn Commercial Paper Programmes
Debt Securities In Issue [Line Items]
Notional amount | $			$ 20,000,000,000			$ 20,000,000,000
Debt securities	3,434			2,704
Certificates of deposit
Debt Securities In Issue [Line Items]
Debt securities	1,667			2,387
Credit linked notes
Debt Securities In Issue [Line Items]
Credit linked notes	60			59
Securitisation programmes
Debt Securities In Issue [Line Items]
Debt securities	£ 436			£ 759

Subordinated Liabilities - Sche

Subordinated Liabilities - Schedule of Subordinated Liabilities (Details) - GBP (£) £ in Millions	Jun. 30, 2022	Dec. 31, 2021
Subordinated liabilities [abstract]
Subordinated liabilities	£ 2,335	£ 2,228

Subordinated Liabilities - Addi

Subordinated Liabilities - Additional Information (Details) - GBP (£) £ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Subordinated liabilities [abstract]
Loss on repurchase of debt securities and subordinated liabilities	£ 1
Loss on repurchase of debt securities		£ 27

Provisions - Summary of Provisi

Provisions - Summary of Provisions Reconciliation (Details) £ in Millions	6 Months Ended
	Jun. 30, 2022 GBP (£)
Disclosure of other provisions [line items]
Beginning balance	£ 364
Additional provisions	144
Provision releaseds	(13)
Utilisation and other	(132)
Ending balance	363
Customer remediation
Disclosure of other provisions [line items]
Beginning balance	44
Additional provisions	25
Provision releaseds	(12)
Utilisation and other	(8)
Ending balance	49
Litigation and other regulatory
Disclosure of other provisions [line items]
Beginning balance	166
Additional provisions	16
Provision releaseds	(1)
Utilisation and other	(15)
Ending balance	166
Bank Levy
Disclosure of other provisions [line items]
Beginning balance	1
Additional provisions	0
Provision releaseds	0
Utilisation and other	(1)
Ending balance	0
Property
Disclosure of other provisions [line items]
Beginning balance	74
Additional provisions	1
Provision releaseds	0
Utilisation and other	(11)
Ending balance	64
ECL on undrawn facilities and guarantees
Disclosure of other provisions [line items]
Beginning balance	38
Additional provisions	10
Provision releaseds	0
Utilisation and other	(2)
Ending balance	46
Restructuring
Disclosure of other provisions [line items]
Beginning balance	28
Additional provisions	8
Provision releaseds	0
Utilisation and other	(12)
Ending balance	24
Other
Disclosure of other provisions [line items]
Beginning balance	13
Additional provisions	84
Provision releaseds	0
Utilisation and other	(83)
Ending balance	£ 14

Provisions - Additional Informa

Provisions - Additional Information (Details) - GBP (£) £ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Future expected provision number
Additional provisions	£ 144
Operational risk provisions
Future expected provision number
Additional provisions	78	£ 50
Fraud loss
Future expected provision number
Additional provisions	£ 63	£ 37

Retirement Benefit Plans - Summ

Retirement Benefit Plans - Summary of Retirement Benefit Plans (Details) - GBP (£) £ in Millions	Jun. 30, 2022	Dec. 31, 2021
Net change in operating assets and liabilities:
Net defined benefit assets	£ 1,982	£ 1,535
Unfunded pension and post-retirement medical benefits
Net change in operating assets and liabilities:
Surplus (deficit) in plan	(29)	(37)
Surplus | Funded defined benefit pension scheme
Net change in operating assets and liabilities:
Surplus (deficit) in plan	£ 2,011	£ 1,572

Retirement Benefit Plans - Addi

Retirement Benefit Plans - Additional Information (Details) - GBP (£) £ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Disclosure of net defined benefit liability (asset) [abstract]
Defined contribution expense	£ 30	£ 33
Defined benefit expense	£ 4	£ 23

Retirement Benefit Plans - Su_2

Retirement Benefit Plans - Summary of Amounts Recognised in Other Comprehensive Income (Details) - GBP (£) £ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Disclosure of net defined benefit liability (asset) [abstract]
Return on plan assets (excluding amounts included in net interest expense)	£ 3,352	£ 383
Actuarial gains arising from experience adjustments	296	(30)
Actuarial gains arising from changes in financial assumptions	(3,974)	(1,098)
Pension remeasurement	£ (326)	£ (745)

Retirement Benefit Plans - Su_3

Retirement Benefit Plans - Summary of Net Assets Recognised (Details) - GBP (£) £ in Millions	Jun. 30, 2022	Dec. 31, 2021
Disclosure of net defined benefit liability (asset) [abstract]
Present value of defined benefit obligations	£ (9,138)	£ (12,878)
Fair value of scheme assets	11,120	14,413
Net defined benefit assets	£ 1,982	£ 1,535

Retirement Benefit Plans - Su_4

Retirement Benefit Plans - Summary of Principal Actuarial Assumptions Used for Defined Benefit Schemes (Details)	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Disclosure of net defined benefit liability (asset) [abstract]
Discount rate for scheme liabilities	3.80%		1.90%
General price inflation	3.10%		3.40%
General salary increase	1%		1%
Expected rate of pension increase	3%		3.20%
Longevity at 60 for current pensioners, on the valuation date:
Males	27 years 6 months	27 years 6 months
Females	30 years 2 months 12 days	30 years 1 month 6 days
Longevity at 60 for future pensioners currently aged 40, on the valuation date:
Males	29 years 1 month 6 days	29 years
Females	31 years 8 months 12 days	31 years 7 months 6 days

Retirement Benefit Plans - Su_5

Retirement Benefit Plans - Summary of Actuarial Assumption Sensitivities (Details) - GBP (£) £ in Millions	6 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
Discount rate
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Description of changes in methods and assumptions	25 bps increase
Increase (decrease) in defined benefit obligation	£ (335)	£ (571)
Percentage of reasonably possible increase in actuarial assumption	0.25%
General price inflation
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Description of changes in methods and assumptions	25 bps increase
Increase (decrease) in defined benefit obligation	£ 239	392
Percentage of reasonably possible increase in actuarial assumption	0.25%
Mortality
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Description of changes in methods and assumptions	Each additional year of longevity assumed
Increase (decrease) in defined benefit obligation	£ 256	£ 478

Contingent Liabilities and Co_3

Contingent Liabilities and Commitments - Summary of Contingent Liabilities and Commitments (Details) - GBP (£) £ in Millions	Jun. 30, 2022	Dec. 31, 2021
Disclosure Of Contingent Liabilities And Commitments [Line Items]
Guarantees and formal standby facilities, credit lines and other commitments	£ 37,652	£ 37,709
Contingent liability for guarantees
Disclosure Of Contingent Liabilities And Commitments [Line Items]
Guarantees given to third parties	428	363
Loan commitments
Disclosure Of Contingent Liabilities And Commitments [Line Items]
Formal standby facilities, credit lines and other commitments	£ 37,224	£ 37,346

Contingent Liabilities and Co_4

Contingent Liabilities and Commitments - Additional Information (Details) £ in Millions		6 Months Ended
	Nov. 02, 2015	Jun. 30, 2022 EUR (€)	Dec. 31, 2021 GBP (£)	Jul. 31, 2020 GBP (£)
Minimum
Disclosure Of Contingent Liabilities And Commitments [Line Items]
Losses on litigation settlements		€ 1,000,000,000
Maximum
Disclosure Of Contingent Liabilities And Commitments [Line Items]
Santander UK liability under indemnity cap		39,850,000
AXA France
Disclosure Of Contingent Liabilities And Commitments [Line Items]
Amount claimed by other party | £			£ 636
UK&I Banks
Disclosure Of Contingent Liabilities And Commitments [Line Items]
Preferred stock issued, threshold value		€ 0
Genworth Financial International Holdings Inc
Disclosure Of Contingent Liabilities And Commitments [Line Items]
Amount awarded to other party | £				£ 624
Visa Europe Ltd
Disclosure Of Contingent Liabilities And Commitments [Line Items]
Visa Europe Ltd sale to Visa Inc	100%

Other Equity Instruments - Summ

Other Equity Instruments - Summary of Other Equity Instruments (Details)	1 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2022 GBP (£)	Jun. 30, 2022 GBP (£)	Dec. 31, 2021 GBP (£)
Disclosure Of Other Equity Instruments [Line Items]
Other equity instruments	£ 1,956,000,000	£ 1,956,000,000	£ 2,191,000,000
$300m Step-up Callable Perpetual Reserve Capital Instruments
Disclosure Of Other Equity Instruments [Line Items]
Capital securities		£ 300,000,000	£ 300,000,000
Interest rate		0.07037	0.07037
Other equity interest maturity period		2026-02	2026-02
Other equity instruments	0	£ 0	£ 235,000,000
- $500m Perpetual Capital Securities
Disclosure Of Other Equity Instruments [Line Items]
Capital securities		£ 500,000,000	£ 500,000,000
Interest rate		0.0675	0.0675
Other equity interest maturity period		2024-06	2024-06
Other equity instruments	£ 496,000,000	£ 496,000,000	£ 496,000,000
- $750m Perpetual Capital Securities
Disclosure Of Other Equity Instruments [Line Items]
Capital securities		£ 750,000,000	£ 750,000,000
Interest rate	0.07375	0.07375	0.07375
Other equity interest maturity period		2022-06	2022-06
Other equity instruments	£ 0	£ 0	£ 750,000,000
- $500m Perpetual Capital Securities
Disclosure Of Other Equity Instruments [Line Items]
Capital securities		£ 500,000,000	£ 500,000,000
Interest rate		0.0518	0.0518
Other equity instruments	0	£ 0	£ 0
- $500m Perpetual Capital Securities
Disclosure Of Other Equity Instruments [Line Items]
Capital securities		£ 500,000,000	£ 500,000,000
Interest rate		0.0630	0.0630
Other equity interest maturity period		2025-03	2025-03
Other equity instruments	500,000,000	£ 500,000,000	£ 500,000,000
- $210m Perpetual Capital Securities
Disclosure Of Other Equity Instruments [Line Items]
Capital securities		£ 210,000,000	£ 210,000,000
Interest rate		0.0425	0.0425
Other equity interest maturity period		2026-03	2026-03
Other equity instruments	210,000,000	£ 210,000,000	£ 210,000,000
- £750m Perpetual Capital Securities
Disclosure Of Other Equity Instruments [Line Items]
Capital securities	£ 750,000,000	£ 750,000,000	£ 750,000,000
Interest rate	0.0650	0.0650	0.0650
Other equity interest maturity period		2027-09	2027-09
Other equity instruments	£ 750,000,000	£ 750,000,000	£ 0

Other Equity Instruments - Addi

Other Equity Instruments - Additional Information (Details)		1 Months Ended	6 Months Ended		12 Months Ended
	Feb. 14, 2022 GBP (£)	Jun. 30, 2022 GBP (£)	Jun. 30, 2022 GBP (£)	Jun. 30, 2021 GBP (£)	Dec. 31, 2021 GBP (£)
Disclosure Of Other Equity Instruments [Line Items]
Repurchase of other equity instruments			£ 985,000,000	£ 210,000,000
$300m Step-up Callable Perpetual Reserve Capital Instruments
Disclosure Of Other Equity Instruments [Line Items]
Repurchase of other equity instruments	£ 300,000,000
Interest rate			0.07037		0.07037
Capital securities			£ 300,000,000		£ 300,000,000
- $750m Perpetual Capital Securities
Disclosure Of Other Equity Instruments [Line Items]
Capital securities purchased and redeemed		£ 750,000,000
Interest rate		0.07375	0.07375		0.07375
Capital securities			£ 750,000,000		£ 750,000,000
- £750m Perpetual Capital Securities
Disclosure Of Other Equity Instruments [Line Items]
Interest rate		0.0650	0.0650		0.0650
Capital securities		£ 750,000,000	£ 750,000,000		£ 750,000,000

Notes to Cash Flows (Details)

Notes to Cash Flows (Details) - GBP (£) £ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021	Dec. 31, 2020
Disclosure Of Cash Flows Explanatory Notes [Line Items]
Cash and cash equivalents restated	£ 42,867	£ 47,228	£ 49,254	£ 46,696
Non-cash items included in profit restated	(827)	(431)
Restricted balances restated	£ 2,137	1,677
Increase (decrease) due to corrections of prior period errors
Disclosure Of Cash Flows Explanatory Notes [Line Items]
Cash and cash equivalents restated		4,339
Increase (decrease) due to voluntary changes in accounting policy
Disclosure Of Cash Flows Explanatory Notes [Line Items]
Non-cash items included in profit restated		214
Increase (decrease) due to changes in accounting policy required by IFRSs
Disclosure Of Cash Flows Explanatory Notes [Line Items]
Cash and cash equivalents restated		(780)	£ (1,580)	£ (985)
Restricted balances restated		£ 780

Assets Charged as Security fo_2

Assets Charged as Security for Liabilities and Collateral Accepted as Security for Assets (Details) - GBP (£) £ in Millions	Jun. 30, 2022	Dec. 31, 2021
Disclosure Of Assets Pledged As Security [Line Items]
Gross assets charged as security for liabilities	£ 24,183	£ 20,199
Internally retained | Securitisations and covered bonds
Disclosure Of Assets Pledged As Security [Line Items]
Notes issued under securitisation and covered bond programmes retained internally	1,780	1,855
Internally retained | Securitisations and covered bonds | Santander UK Plc
Disclosure Of Assets Pledged As Security [Line Items]
Internally retained securitisation and covered bond issuances available for creating collateral	751	767
Third party bilateral secured funding transactions | Securitisations and covered bonds
Disclosure Of Assets Pledged As Security [Line Items]
Notes issued to Santander UK plc/subsidiaries as collateral	£ 500	£ 500

Related Party Disclosures (Deta

Related Party Disclosures (Details) - Santander Financial Services PLC - Mortgages £ in Millions	1 Months Ended
	May 31, 2022 GBP (£)
Disclosure of transactions between related parties [line items]
Book value of financial assets transferred	£ 624
Proceeds from transfer of financial assets	631
Price premium on transfer of financial assets	£ 7

Financial Instruments - Disclos

Financial Instruments - Disclosure of Analysis of Fair Value of Financial Instruments Carried at Amortised Cost (Details) - GBP (£) £ in Millions	Jun. 30, 2022	Dec. 31, 2021
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Loans and advances to customers	£ 217,012	£ 210,094
Loans and advances to banks	793	1,169
Reverse repurchase agreements - non trading	8,793	12,683
Deposits by customers	189,729	192,926
Deposits by banks	35,182	33,855
Repurchase agreements - non trading	6,910	11,718
Debt securities in issue	29,521	25,520
Subordinated liabilities	2,335	2,228
Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Total financial liabilities	263,677	266,247
Financial assets at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Financial assets	226,754	224,452
Deposits by customers | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Deposits by customers	189,729	192,926
Deposits by banks | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Deposits by banks	35,182	33,855
Repurchase agreements - non trading | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Repurchase agreements - non trading	6,910	11,718
Debt securities in issue | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Debt securities in issue	29,521	25,520
Subordinated liabilities | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Subordinated liabilities	2,335	2,228
Loans and advances to customers | Financial assets at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Loans and advances to customers	217,012	210,094
Loans and advances to banks | Financial assets at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Loans and advances to banks	793	1,169
Reverse repurchase agreements – non trading | Financial assets at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Reverse repurchase agreements - non trading	8,793	12,683
Other financial assets at amortised cost | Financial assets at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Other financial assets at amortised cost	156	506
Fair value | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Total financial liabilities	263,880	267,251
Fair value | Financial assets at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Financial assets	224,963	227,171
Fair value | Deposits by customers | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Deposits by customers	189,726	192,946
Fair value | Deposits by banks | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Deposits by banks	35,075	33,855
Fair value | Repurchase agreements - non trading | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Repurchase agreements - non trading	6,910	11,718
Fair value | Debt securities in issue | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Debt securities in issue	29,540	26,107
Fair value | Subordinated liabilities | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Subordinated liabilities	2,629	2,625
Fair value | Loans and advances to customers | Financial assets at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Loans and advances to customers	215,234	212,811
Fair value | Loans and advances to banks | Financial assets at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Loans and advances to banks	793	1,169
Fair value | Reverse repurchase agreements – non trading | Financial assets at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Reverse repurchase agreements - non trading	8,785	12,679
Fair value | Other financial assets at amortised cost | Financial assets at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Other financial assets at amortised cost	151	512
Level 1 | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Total financial liabilities	2,368	1,000
Level 1 | Financial assets at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Financial assets	151	164
Level 1 | Deposits by customers | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Deposits by customers	0	0
Level 1 | Deposits by banks | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Deposits by banks	0	0
Level 1 | Repurchase agreements - non trading | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Repurchase agreements - non trading	0	0
Level 1 | Debt securities in issue | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Debt securities in issue	2,349	963
Level 1 | Subordinated liabilities | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Subordinated liabilities	19	37
Level 1 | Loans and advances to customers | Financial assets at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Loans and advances to customers	0	0
Level 1 | Loans and advances to banks | Financial assets at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Loans and advances to banks	0	0
Level 1 | Reverse repurchase agreements – non trading | Financial assets at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Reverse repurchase agreements - non trading	0	0
Level 1 | Other financial assets at amortised cost | Financial assets at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Other financial assets at amortised cost	151	164
Level 2 | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Total financial liabilities	67,311	71,812
Level 2 | Financial assets at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Financial assets	9,578	13,970
Level 2 | Deposits by customers | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Deposits by customers	210	48
Level 2 | Deposits by banks | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Deposits by banks	35,012	33,770
Level 2 | Repurchase agreements - non trading | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Repurchase agreements - non trading	6,910	11,718
Level 2 | Debt securities in issue | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Debt securities in issue	22,569	23,926
Level 2 | Subordinated liabilities | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Subordinated liabilities	2,610	2,350
Level 2 | Loans and advances to customers | Financial assets at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Loans and advances to customers	0	0
Level 2 | Loans and advances to banks | Financial assets at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Loans and advances to banks	793	1,169
Level 2 | Reverse repurchase agreements – non trading | Financial assets at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Reverse repurchase agreements - non trading	8,785	12,453
Level 2 | Other financial assets at amortised cost | Financial assets at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Other financial assets at amortised cost	0	348
Level 3 | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Total financial liabilities	194,201	194,439
Level 3 | Financial assets at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Financial assets	215,234	213,037
Level 3 | Deposits by customers | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Deposits by customers	189,516	192,898
Level 3 | Deposits by banks | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Deposits by banks	63	85
Level 3 | Repurchase agreements - non trading | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Repurchase agreements - non trading	0	0
Level 3 | Debt securities in issue | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Debt securities in issue	4,622	1,218
Level 3 | Subordinated liabilities | Financial liabilities at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Subordinated liabilities	0	238
Level 3 | Loans and advances to customers | Financial assets at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Loans and advances to customers	215,234	212,811
Level 3 | Loans and advances to banks | Financial assets at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Loans and advances to banks	0	0
Level 3 | Reverse repurchase agreements – non trading | Financial assets at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Reverse repurchase agreements - non trading	0	226
Level 3 | Other financial assets at amortised cost | Financial assets at amortised cost
Disclosure Of Fair Values Of Financial Instruments Carried At Amortised Cost [Line Items]
Other financial assets at amortised cost	£ 0	£ 0

Financial Instruments - Discl_2

Financial Instruments - Disclosure of Analysis of Fair Value of Financial Instruments Measured at Fair Value on a Recurring Basis (Details) - GBP (£) £ in Millions	6 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	£ 7,339	£ 7,717
Total liabilities at fair value	1,547	1,580
Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	720	777
Other financial liabilities at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	827	803
Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	2,271	1,681
Other financial assets at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	155	185
Financial assets at FVOCI
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	4,913	5,851
Level 1
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	4,894	5,833
Total liabilities at fair value	0	0
Level 1 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	0	0
Level 1 | Other financial liabilities at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	0	0
Level 1 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	0	0
Level 1 | Other financial assets at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	0	0
Level 1 | Financial assets at FVOCI
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	4,894	5,833
Level 2
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	2,230	1,635
Total liabilities at fair value	1,528	1,542
Level 2 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	704	745
Level 2 | Other financial liabilities at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	824	797
Level 2 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	2,230	1,635
Level 2 | Other financial assets at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	0	0
Level 2 | Financial assets at FVOCI
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	0	0
Level 3
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	215	249
Total liabilities at fair value	19	38
Level 3 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	16	32
Level 3 | Other financial liabilities at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	3	6
Level 3 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	41	46
Level 3 | Other financial assets at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	155	185
Level 3 | Financial assets at FVOCI
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	£ 19	18
Exchange rate contracts | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Valuation technique	A
Total liabilities at fair value	£ 427	506
Exchange rate contracts | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	£ 1,909	1,194
Valuation technique	A
Exchange rate contracts | Level 1 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	£ 0	0
Exchange rate contracts | Level 1 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	0	0
Exchange rate contracts | Level 2 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	427	506
Exchange rate contracts | Level 2 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	1,909	1,193
Exchange rate contracts | Level 3 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	0	0
Exchange rate contracts | Level 3 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	£ 0	1
Interest rate contracts | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Valuation technique	A & C
Total liabilities at fair value	£ 2,041	1,438
Interest rate contracts | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	£ 2,004	1,547
Valuation technique	A & C
Interest rate contracts | Level 1 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	£ 0	0
Interest rate contracts | Level 1 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	0	0
Interest rate contracts | Level 2 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	2,038	1,436
Interest rate contracts | Level 2 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	2,002	1,547
Interest rate contracts | Level 3 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	3	2
Interest rate contracts | Level 3 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	£ 2	0
Equity and credit contracts | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Valuation technique	B & D
Total liabilities at fair value	£ 35	54
Equity and credit contracts | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	£ 141	161
Valuation technique	B & D
Equity and credit contracts | Level 1 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	£ 0	0
Equity and credit contracts | Level 1 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	0	0
Equity and credit contracts | Level 2 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	22	24
Equity and credit contracts | Level 2 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	102	116
Equity and credit contracts | Level 3 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	13	30
Equity and credit contracts | Level 3 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	39	45
Netting | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	(1,783)	(1,221)
Netting | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	(1,783)	(1,221)
Netting | Level 1 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	0	0
Netting | Level 1 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	0	0
Netting | Level 2 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	(1,783)	(1,221)
Netting | Level 2 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	(1,783)	(1,221)
Netting | Level 3 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	0	0
Netting | Level 3 | Derivative financial instruments
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	0	0
Loans and advances to customers | Other financial assets at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	£ 60	74
Valuation technique	A
Loans and advances to customers | Financial assets at FVOCI
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	£ 19	18
Valuation technique	D
Loans and advances to customers | Level 1 | Other financial assets at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	£ 0	0
Loans and advances to customers | Level 1 | Financial assets at FVOCI
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	0	0
Loans and advances to customers | Level 2 | Other financial assets at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	0	0
Loans and advances to customers | Level 2 | Financial assets at FVOCI
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	0	0
Loans and advances to customers | Level 3 | Other financial assets at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	60	74
Loans and advances to customers | Level 3 | Financial assets at FVOCI
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	19	18
Debt securities | Other financial assets at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	£ 95	111
Valuation technique	A, B & D
Debt securities | Financial assets at FVOCI
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	£ 4,894	5,833
Valuation technique	D
Debt securities | Level 1 | Other financial assets at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	£ 0	0
Debt securities | Level 1 | Financial assets at FVOCI
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	4,894	5,833
Debt securities | Level 2 | Other financial assets at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	0	0
Debt securities | Level 2 | Financial assets at FVOCI
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	0	0
Debt securities | Level 3 | Other financial assets at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	95	111
Debt securities | Level 3 | Financial assets at FVOCI
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Assets at fair value	£ 0	0
Debt securities in issue | Other financial liabilities at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Valuation technique	A
Total liabilities at fair value	£ 466	560
Debt securities in issue | Level 1 | Other financial liabilities at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	0	0
Debt securities in issue | Level 2 | Other financial liabilities at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	463	555
Debt securities in issue | Level 3 | Other financial liabilities at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	£ 3	5
Structured deposits | Other financial liabilities at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Valuation technique	A
Total liabilities at fair value	£ 346	223
Structured deposits | Level 1 | Other financial liabilities at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	0	0
Structured deposits | Level 2 | Other financial liabilities at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	346	223
Structured deposits | Level 3 | Other financial liabilities at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	£ 0	0
Collateral and associated financial guarantees | Other financial liabilities at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Valuation technique	D
Total liabilities at fair value	£ 15	20
Collateral and associated financial guarantees | Level 1 | Other financial liabilities at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	0	0
Collateral and associated financial guarantees | Level 2 | Other financial liabilities at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	15	19
Collateral and associated financial guarantees | Level 3 | Other financial liabilities at FVTPL
Disclosure Of Fair Value Measurements Of Assets And Liabilities [Line Items]
Total liabilities at fair value	£ 0	£ 1

Financial Instruments - Additio

Financial Instruments - Additional Information (Details) - GBP (£) £ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Abstract]
Transfers out of Level 1 into Level 2 of fair value hierarchy, assets held at end of reporting period	£ 0	£ 0
Transfers out of Level 2 into Level 1 of fair value hierarchy, assets held at end of reporting period	0	0
Transfers in	0	0
Transfers out of Level 3 of fair value hierarchy, assets	0	0
Transfers out of Level 1 into Level 2 of fair value hierarchy, liabilities held at end of reporting period	0	0
Transfers out of Level 2 into Level 1 of fair value hierarchy, liabilities held at end of reporting period	0	0
Transfers into Level 3 of fair value hierarchy, liabilities	0	0
Transfers out of Level 3 of fair value hierarchy, liabilities	£ 0	£ 0

Financial Instruments - Summary

Financial Instruments - Summary of Fair Value Adjustment (Details) - GBP (£) £ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
Risk related adjustments
Disclosure of financial assets [line items]
Fair value adjustments	£ 10	£ 20
- Bid-offer and trade specific adjustments
Disclosure of financial assets [line items]
Fair value adjustments	(15)	(9)
- Uncertainty
Disclosure of financial assets [line items]
Fair value adjustments	15	20
- Credit risk adjustment
Disclosure of financial assets [line items]
Fair value adjustments	6	6
- Funding fair value adjustment
Disclosure of financial assets [line items]
Fair value adjustments	£ 4	£ 3

Financial Instruments - Summa_2

Financial Instruments - Summary of Reconciliation of Fair Value Measurement in Level 3 of the Fair Value Hierarchy (Details) - GBP (£) £ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Disclosure of fair value measurement of assets [line items]
Beginning balance	£ 287,098
Beginning balance	(270,996)
Transfers in	0	£ 0
Transfers in	0	£ 0
Ending Balance	284,317
Ending Balance	(268,644)
Level 3 | Other financial liabilities at FVTPL
Disclosure of fair value measurement of assets [line items]
Beginning balance	(6)
Fair value movements	5
Transfers in	0
Netting	(4)
Settlements	2
Ending Balance	(3)
Gains/(losses) recognised in profit or loss/other comprehensive income relating to assets and liabilities held at the end of the period	5
Level 3 | Financial liabilities at fair value
Disclosure of fair value measurement of assets [line items]
Beginning balance	(38)
Fair value movements	5
Transfers in	(2)
Netting	(4)
Settlements	20
Ending Balance	(19)
Gains/(losses) recognised in profit or loss/other comprehensive income relating to assets and liabilities held at the end of the period	5
Level 3 | Derivatives
Disclosure of fair value measurement of assets [line items]
Beginning balance	(32)
Fair value movements	0
Transfers in	(2)
Netting	0
Settlements	18
Ending Balance	(16)
Gains/(losses) recognised in profit or loss/other comprehensive income relating to assets and liabilities held at the end of the period	0
Level 3 | Other financial assets at FVTPL
Disclosure of fair value measurement of assets [line items]
Beginning balance	185
Fair value movements	(18)
Transfers in	0
Netting	0
Settlements	(12)
Ending Balance	155
Gains/(losses) recognised in profit or loss/other comprehensive income relating to assets and liabilities held at the end of the period	(18)
Level 3 | Financial assets at FVOCI
Disclosure of fair value measurement of assets [line items]
Beginning balance	18
Fair value movements	1
Transfers in	0
Netting	0
Settlements	0
Ending Balance	19
Gains/(losses) recognised in profit or loss/other comprehensive income relating to assets and liabilities held at the end of the period	1
Level 3 | Financial assets at fair value
Disclosure of fair value measurement of assets [line items]
Beginning balance	249
Fair value movements	(19)
Transfers in	0
Netting	0
Settlements	(15)
Ending Balance	215
Gains/(losses) recognised in profit or loss/other comprehensive income relating to assets and liabilities held at the end of the period	(19)
Level 3 | Derivatives
Disclosure of fair value measurement of assets [line items]
Beginning balance	46
Fair value movements	(2)
Transfers in	0
Netting	0
Settlements	(3)
Ending Balance	41
Gains/(losses) recognised in profit or loss/other comprehensive income relating to assets and liabilities held at the end of the period	£ (2)

Interest Rate Benchmark Refor_2

Interest Rate Benchmark Reform - Schedule of Amounts Affected by IBOR Reform (Details) - GBP (£) £ in Millions	Jun. 30, 2022	Dec. 31, 2021
Assets
Derivative financial instruments	£ 2,271	£ 1,681
Other financial assets at FVTPL	155	185
Financial assets at amortised cost	156	506
Total assets	284,317	287,098
Liabilities
Derivative financial instruments	720	777
Other financial liabilities at fair value through profit or loss	827	803
Total liabilities	268,644	270,996
GBP LIBOR
Assets
Derivative financial instruments	0	0
Other financial assets at FVTPL		8
Financial assets at amortised cost	85	1,373
Total assets	85	1,381
Liabilities
Derivative financial instruments	130	338
Other financial liabilities at fair value through profit or loss	0	0
Financial liabilities at amortised cost		34
Total liabilities	130	372
Off-balance sheet commitments given	8	338
USD LIBOR
Assets
Derivative financial instruments	1,650	1,480
Other financial assets at FVTPL		0
Financial assets at amortised cost	17	81
Total assets	1,667	1,561
Liabilities
Derivative financial instruments	1,830	1,831
Other financial liabilities at fair value through profit or loss	3	5
Financial liabilities at amortised cost		185
Total liabilities	1,833	2,021
Off-balance sheet commitments given	79	59
Other
Assets
Derivative financial instruments	0	0
Other financial assets at FVTPL		0
Financial assets at amortised cost	0	1
Total assets	0	1
Liabilities
Derivative financial instruments	0	0
Other financial liabilities at fair value through profit or loss	0	0
Financial liabilities at amortised cost		0
Total liabilities	0	0
Off-balance sheet commitments given	0	0
Total
Assets
Derivative financial instruments	1,650	1,480
Other financial assets at FVTPL		8
Financial assets at amortised cost	102	1,455
Total assets	1,752	2,943
Liabilities
Derivative financial instruments	1,960	2,169
Other financial liabilities at fair value through profit or loss	3	5
Financial liabilities at amortised cost		219
Total liabilities	1,963	2,393
Off-balance sheet commitments given	£ 87	£ 397

Interest Rate Benchmark Refor_3

Interest Rate Benchmark Reform - Schedule of Derivatives Directly Affected by IBOR Reform Uncertainties (Details) - GBP (£) £ in Millions	Jun. 30, 2022	Dec. 31, 2021
GBP LIBOR
Disclosure Of Analysis Of Notional And Fair Values Of Derivatives By Trading And Settlement Method [Line Items]
Notional value of hedging instruments	0	0
GBP LIBOR | Maturing after cessation date
Disclosure Of Analysis Of Notional And Fair Values Of Derivatives By Trading And Settlement Method [Line Items]
Notional value of hedging instruments	0	0
USD LIBOR
Disclosure Of Analysis Of Notional And Fair Values Of Derivatives By Trading And Settlement Method [Line Items]
Notional value of hedging instruments	3,057	2,746
USD LIBOR | Maturing after cessation date
Disclosure Of Analysis Of Notional And Fair Values Of Derivatives By Trading And Settlement Method [Line Items]
Notional value of hedging instruments	3,057	2,746
Other
Disclosure Of Analysis Of Notional And Fair Values Of Derivatives By Trading And Settlement Method [Line Items]
Notional value of hedging instruments	0	0
Other | Maturing after cessation date
Disclosure Of Analysis Of Notional And Fair Values Of Derivatives By Trading And Settlement Method [Line Items]
Notional value of hedging instruments	0	0
Total
Disclosure Of Analysis Of Notional And Fair Values Of Derivatives By Trading And Settlement Method [Line Items]
Notional value of hedging instruments	3,057	2,746
Total | Maturing after cessation date
Disclosure Of Analysis Of Notional And Fair Values Of Derivatives By Trading And Settlement Method [Line Items]
Notional value of hedging instruments	3,057	2,746
Cash flow hedges | GBP LIBOR
Disclosure Of Analysis Of Notional And Fair Values Of Derivatives By Trading And Settlement Method [Line Items]
Notional value of hedging instruments	0	0
Cash flow hedges | GBP LIBOR | Maturing after cessation date
Disclosure Of Analysis Of Notional And Fair Values Of Derivatives By Trading And Settlement Method [Line Items]
Notional value of hedging instruments	0	0
Cash flow hedges | USD LIBOR
Disclosure Of Analysis Of Notional And Fair Values Of Derivatives By Trading And Settlement Method [Line Items]
Notional value of hedging instruments	2,881	2,586
Cash flow hedges | USD LIBOR | Maturing after cessation date
Disclosure Of Analysis Of Notional And Fair Values Of Derivatives By Trading And Settlement Method [Line Items]
Notional value of hedging instruments	2,881	2,586
Cash flow hedges | Other
Disclosure Of Analysis Of Notional And Fair Values Of Derivatives By Trading And Settlement Method [Line Items]
Notional value of hedging instruments	0	0
Cash flow hedges | Other | Maturing after cessation date
Disclosure Of Analysis Of Notional And Fair Values Of Derivatives By Trading And Settlement Method [Line Items]
Notional value of hedging instruments	0	0
Cash flow hedges | Total
Disclosure Of Analysis Of Notional And Fair Values Of Derivatives By Trading And Settlement Method [Line Items]
Notional value of hedging instruments	2,881	2,586
Cash flow hedges | Total | Maturing after cessation date
Disclosure Of Analysis Of Notional And Fair Values Of Derivatives By Trading And Settlement Method [Line Items]
Notional value of hedging instruments	2,881	2,586
Fair value hedges | GBP LIBOR
Disclosure Of Analysis Of Notional And Fair Values Of Derivatives By Trading And Settlement Method [Line Items]
Notional value of hedging instruments	0	0
Fair value hedges | GBP LIBOR | Maturing after cessation date
Disclosure Of Analysis Of Notional And Fair Values Of Derivatives By Trading And Settlement Method [Line Items]
Notional value of hedging instruments	0	0
Fair value hedges | USD LIBOR
Disclosure Of Analysis Of Notional And Fair Values Of Derivatives By Trading And Settlement Method [Line Items]
Notional value of hedging instruments	176	160
Fair value hedges | USD LIBOR | Maturing after cessation date
Disclosure Of Analysis Of Notional And Fair Values Of Derivatives By Trading And Settlement Method [Line Items]
Notional value of hedging instruments	176	160
Fair value hedges | Other
Disclosure Of Analysis Of Notional And Fair Values Of Derivatives By Trading And Settlement Method [Line Items]
Notional value of hedging instruments	0	0
Fair value hedges | Other | Maturing after cessation date
Disclosure Of Analysis Of Notional And Fair Values Of Derivatives By Trading And Settlement Method [Line Items]
Notional value of hedging instruments	0	0
Fair value hedges | Total
Disclosure Of Analysis Of Notional And Fair Values Of Derivatives By Trading And Settlement Method [Line Items]
Notional value of hedging instruments	176	160
Fair value hedges | Total | Maturing after cessation date
Disclosure Of Analysis Of Notional And Fair Values Of Derivatives By Trading And Settlement Method [Line Items]
Notional value of hedging instruments	176	160

Discontinued Operations and A_3

Discontinued Operations and Assets Held for Sale - Disclosure of Financial Performance Relating to Discontinued Operations (Details) - GBP (£) £ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Disclosure of analysis of single amount of discontinued operations [line items]
Net interest income	£ 2,120	£ 1,905
Net fee and commission income	168	151
Total operating income	2,390	2,191
Operating expenses before credit impairment losses, provisions and charges	(1,172)	(1,328)
Credit impairment losses	(118)	70
Provisions for other liabilities and charges	(118)	(190)
Total operating credit impairment (losses)/write-backs, provisions and charges	(236)	(120)
Profit from discontinued operations before tax	0	33
Tax on profit from discontinued operations	0	(9)
Profit from discontinued operations after tax	0	24
Discontinued operations
Disclosure of analysis of single amount of discontinued operations [line items]
Net interest income	0	24
Net fee and commission income	0	27
Total operating income	0	51
Operating expenses before credit impairment losses, provisions and charges	0	(22)
Credit impairment losses	0	7
Provisions for other liabilities and charges	0	(3)
Total operating credit impairment (losses)/write-backs, provisions and charges	£ 0	£ 4

Discontinued Operations and A_4

Discontinued Operations and Assets Held for Sale - Additional Information (Details) - GBP (£) £ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Discontinued Operations and Assets and Liabilities Held for Sale [Abstract]
Gain (loss) recognised on measurement to fair value less costs to sell or on disposal of assets or disposal groups constituting discontinued operation	£ 0	£ 0
Cash flows from (used in) operating activities, discontinued operations	0	1,754
Cash flows from (used in) investing activities, discontinued operations	0	0
Cash flows from (used in) financing activities, discontinued operations	£ 0	£ 0

Discontinued Operations and A_5

Discontinued Operations and Assets Held for Sale - Disclosure of Assets Held for Sale (Details) - GBP (£) £ in Millions	Jun. 30, 2022	Dec. 31, 2021
Disclosure Of Assets And Liabilities Classified As Held For Sale [Line Items]
Assets held for sale	£ 49	£ 0
Property, plant and equipment
Disclosure Of Assets And Liabilities Classified As Held For Sale [Line Items]
Assets held for sale	£ 49

Events After the Balance Shee_2

Events After the Balance Sheet Date (Details)	6 Months Ended
	Jun. 30, 2022
Disclosure of non-adjusting events after reporting period [abstract]
Description of nature of non-adjusting event after reporting period	There have been no significant events between 30 June 2022 and the date of approval of these financial statements which would require a change to or additional disclosure in the financial statements.