ChipMOS (IMOS) 20-F 11 Apr 24 2023 FY Annual report (foreign) Financial data

Cover Page

Cover Page	12 Months Ended
	Dec. 31, 2023 shares
Document Information [Line Items]
Document Type	20-F
Amendment Flag	false
Document Period End Date	Dec. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Entity Registrant Name	ChipMOS TECHNOLOGIES INC.
Entity Central Index Key	0001123134
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding	727,240,126
Document Annual Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes
Document Shell Company Report	false
Entity Incorporation, State or Country Code	F5
Document Financial Statement Error Correction [Flag]	false
Document Accounting Standard	International Financial Reporting Standards
Entity Voluntary Filers	No
Entity Address, Address Line One	No. 1, R&D Road 1
Entity Address, Address Line Two	Hsinchu Science Park
Entity Address, City or Town	Hsinchu
Entity Address, Country	TW
Entity Address, Postal Zip Code	300-092
ICFR Auditor Attestation Flag	true
Auditor Name	PricewaterhouseCoopers, Taiwan
Auditor Firm ID	1345
Auditor Location	Taipei, Taiwan
Document Registration Statement	false
Securities Act File Number	001-37928
ADR [member]
Document Information [Line Items]
Trading Symbol	IMOS
Title of 12(b) Security	American Depositary Shares
Security Exchange Name	NASDAQ
Ordinary shares [member]
Document Information [Line Items]
Title of 12(b) Security	Common Shares, par value NT$10 per share
No Trading Symbol Flag	true
Security Exchange Name	NASDAQ
Business Contact [Member]
Document Information [Line Items]
Entity Address, Address Line One	No. 1, R&D Road 1
Entity Address, Address Line Two	Hsinchu Science Park
Entity Address, City or Town	Hsinchu
Entity Address, Country	TW
Entity Address, Postal Zip Code	300-092
City Area Code	886
Local Phone Number	3-577-0055
Contact Personnel Name	Silvia Su

Consolidated Statements of Fina

Consolidated Statements of Financial Position $ in Thousands, $ in Thousands	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)
Current assets
Cash and cash equivalents	$ 12,354,035	$ 403,463	$ 9,896,604
Current financial assets at fair value through profit or loss	42,735	1,396	128,224
Current financial assets at amortized cost	41,066	1,341	98,731
Current contract assets	383,883	12,537	381,358
Accounts receivable, net	5,326,381	173,951	4,381,563
Other receivables	44,576	1,456	131,863
Current tax assets	403	13
Inventories	2,568,648	83,888	3,210,409
Prepayments	120,273	3,928	123,377
Non-current assets held for sale, net	4,278,658	139,734
Total current assets	25,160,658	821,707	18,352,129
Non-current assets
Non-current financial assets at fair value through other comprehensive income	120,317	3,929	338,102
Non-current financial assets at amortized cost	37,411	1,222	37,362
Investments accounted for using equity method	290,542	9,489	4,353,448
Property, plant and equipment, net	19,139,503	625,065	20,446,205
Right-of-use assets	1,037,502	33,883	898,992
Deferred tax assets	163,282	5,333	159,286
Refundable deposits	20,707	676	21,771
Other non-current assets	190,562	6,223	335,650
Total non-current assets	20,999,826	685,820	26,590,816
Total assets	46,160,484	1,507,527	44,942,945
Current liabilities
Notes payable	484	16	132
Accounts payable	784,919	25,634	560,802
Other payables	3,479,045	113,620	3,796,481
Other payables - related parties	58,549	1,912
Current tax liabilities	505,600	16,512	361,770
Current provisions	33,564	1,096	26,643
Current lease liabilities	251,668	8,219	160,955
Long-term bank loans, current portion	2,263,718	73,930	1,522,917
Current refund liabilities	37,667	1,230	37,123
Other current liabilities	23,611	771	22,318
Total current liabilities	7,438,825	242,940	6,489,141
Non-current liabilities
Long-term bank loans	12,648,001	413,063	12,444,884
Deferred tax liabilities	127,193	4,154	201,741
Non-current lease liabilities	813,733	26,575	759,447
Long-term deferred revenue	120,963	3,950	127,657
Net defined benefit liability, non-current	227,337	7,425	259,215
Guarantee deposits	21,235	694	21,600
Total non-current liabilities	13,958,462	455,861	13,814,544
Total liabilities	21,397,287	698,801	20,303,685
Equity attributable to equity holders of the Company
Capital stock	7,272,401	237,505	7,272,401
Capital surplus	6,055,773	197,772	6,055,773
Retained earnings
Legal reserve	2,930,973	95,721	2,575,987
Unappropriated retained earnings	8,455,690	276,149	8,506,816
Other equity interest	48,360	1,579	228,283
Total equity	24,763,197	808,726	24,639,260
Total liabilities and equity	$ 46,160,484	$ 1,507,527	$ 44,942,945

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($) $ / shares	Dec. 31, 2023 USD ($) $ / shares	Dec. 31, 2022 TWD ($) $ / shares	Dec. 31, 2021 TWD ($) $ / shares
Consolidated statements of comprehensive income [Line Items]
Revenue	$ 21,356,228	$ 697,460	$ 23,517,064	$ 27,400,035
Cost of revenue	(17,806,803)	(581,542)	(18,605,007)	(20,146,057)
Gross profit	3,549,425	115,918	4,912,057	7,253,978
Sales and marketing expenses	(135,661)	(4,431)	(128,029)	(73,928)
General and administrative expenses	(497,742)	(16,255)	(538,684)	(604,029)
Research and development expenses	(1,093,513)	(35,712)	(1,158,598)	(1,139,219)
Other income (expenses), net	85,943	2,807	129,933	125,587
Operating profit	1,908,452	62,327	3,216,679	5,562,389
Interest income	193,189	6,309	57,199	9,980
Other income	77,583	2,534	66,991	34,496
Other gains and losses	135,501	4,425	386,567	(65,829)
Finance costs	(266,390)	(8,700)	(153,279)	(131,184)
Share of profit of associates and joint ventures accounted for using equity method	219,891	7,182	453,715	625,733
Profit before income tax	2,268,226	74,077	4,027,872	6,035,585
Income tax expense	(300,661)	(9,819)	(588,175)	(1,098,318)
Profit for the year	1,967,565	64,258	3,439,697	4,937,267
Other comprehensive income (loss):
(Loss) profit on remeasurements of defined benefit plans	10,699	350	222,234	(14,999)
Unrealized gain (loss) on valuation of equity instruments at fair value through other comprehensive income	(217,785)	(7,113)	(46,419)	122,514
Share of other comprehensive income (loss) of associates and joint ventures accounted for using equity method that will not be reclassified to profit or loss	12,993	424	(28,254)	28,843
Income tax effect on components that will not be reclassified to profit or loss	49,498	1,617	(31,888)	(27,460)
Components of other comprehensive income (loss) that will not be reclassified to profit or loss	(144,595)	(4,722)	115,673	108,898
Exchange differences on translation of foreign operations	16,713	546	68,656	(24,695)
Equity directly related to non-current assets held for sale	(43,094)	(1,408)
Components of other comprehensive (loss) income that will be reclassified to profit or loss	(26,381)	(862)	68,656	(24,695)
Other comprehensive income (loss), net of income tax	(170,976)	(5,584)	184,329	84,203
Total comprehensive income (loss) for the year	$ 1,796,589	$ 58,674	$ 3,624,026	$ 5,021,470
Ordinary shares [member]
Other comprehensive income (loss):
Earnings per share - basic | (per share)	$ 2.71	$ 0.09	$ 4.73	$ 6.79
Earnings per share - diluted | (per share)	2.68	0.09	4.63	6.65
American depositary share (each representing 20 common shares) [member]
Other comprehensive income (loss):
Earnings per share - basic | (per share)	54.11	1.77	94.6	135.78
Earnings per share - diluted | (per share)	$ 53.54	$ 1.75	$ 92.63	$ 132.93

Consolidated Statements of Chan

Consolidated Statements of Changes in Equity $ in Thousands, $ in Thousands	TWD ($)	USD ($)	Capital stock [member] TWD ($)	Capital surplus [member] TWD ($)	Legal reserve [member] TWD ($)	Special reserve [member] TWD ($)	Unappropriated retained earnings [member] TWD ($)	Financial statements translation differences of foreign operations [member] TWD ($)	Unrealized gain (loss) on valuation of financial assets at fair value through other comprehensive income [member] TWD ($)	Equity directly related to non-current assets held for sale [member] TWD ($)
Beginning Balance at Dec. 31, 2020	$ 20,715,839		$ 7,272,401	$ 6,050,787	$ 1,837,894	$ 19,802	$ 5,401,569	$ (61,330)	$ 194,716
Profit for the year	4,937,267						4,937,267
Other comprehensive income (loss)	84,203						(4,251)	(24,695)	113,149
Total comprehensive income (loss) for the year	5,021,470						4,933,016	(24,695)	113,149
Appropriation of prior year's earnings:
Legal reserve					232,611		(232,611)
Special reserve						$ (19,802)	19,802
Cash dividends	(1,599,928)						(1,599,928)
Changes in associates accounted for using equity method	4,834			4,834
Ending Balance at Dec. 31, 2021	24,142,215		7,272,401	6,055,621	2,070,505		8,521,848	(86,025)	307,865
Profit for the year	3,439,697						3,439,697
Other comprehensive income (loss)	184,329						177,886	68,656	(62,213)
Total comprehensive income (loss) for the year	3,624,026						3,617,583	68,656	(62,213)
Appropriation of prior year's earnings:
Legal reserve					505,482		(505,482)
Cash dividends	(3,127,133)						(3,127,133)
Changes in associates accounted for using equity method	152			152
Ending Balance at Dec. 31, 2022	24,639,260		7,272,401	6,055,773	2,575,987		8,506,816	(17,369)	245,652
Profit for the year	1,967,565	$ 64,258					1,967,565
Other comprehensive income (loss)	(170,976)	(5,584)					8,947	16,713	(153,542)	$ (43,094)
Total comprehensive income (loss) for the year	1,796,589	58,674					1,976,512	16,713	(153,542)	(43,094)
Appropriation of prior year's earnings:
Legal reserve					354,986		(354,986)
Cash dividends	(1,672,652)						(1,672,652)
Ending Balance at Dec. 31, 2023	$ 24,763,197	$ 808,726	$ 7,272,401	$ 6,055,773	$ 2,930,973		$ 8,455,690	$ (656)	$ 92,110	$ (43,094)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Cash flows from operating activities
Profit before income tax	$ 2,268,226	$ 74,077	$ 4,027,872	$ 6,035,585
Adjustments to reconcile profit (loss)
Depreciation expenses	4,779,333	156,085	4,751,902	4,634,112
Expected credit losses (gains)	(302)	(10)	897	299
Interest expense	265,957	8,686	142,439	120,998
Interest income	(193,189)	(6,309)	(57,199)	(9,980)
Dividend income	(6,592)	(215)	(9,816)	(4,690)
Share of profit of associates and joint ventures accounted for using equity method	(219,891)	(7,182)	(453,715)	(625,733)
(Gain) loss on valuation of financial assets at fair value through profit or loss	(39,254)	(1,282)	69,404	(15,262)
Gain on disposal of property, plant and equipment, net	(18,431)	(602)	(74,548)	(33,935)
Gain from lease modifications			(139)	(891)
Impairment loss on property, plant and equipment	9,236	302	12,721	4,843
Deferred revenue	(20,839)	(681)	(17,859)	(12,389)
Financial assets at fair value through profit or loss	124,743	4,074	162,332	(290,637)
Current contract assets	(2,470)	(81)	18,788	(11,242)
Accounts and notes receivable	(944,603)	(30,849)	1,962,959	(980,816)
Other receivables	48,736	1,592	15,849	(46,089)
Inventories	641,761	20,959	(3,232)	(1,105,102)
Prepayments	3,104	101	37,748	(67,401)
Other non-current assets				6,915
Accounts and notes payable	224,469	7,331	(451,480)	42,694
Other payables	(90,786)	(2,965)	(161,212)	471,766
Current provisions	6,921	226	22,362	818
Current refund liabilities	544	18	27,274	(15)
Other current liabilities	1,293	42	8,097	(6,838)
Net defined benefit liability, non-current	(21,179)	(692)	(21,839)	(23,362)
Cash generated from operations	6,816,787	222,625	10,009,605	8,083,648
Interest received	194,136	6,340	42,170	10,344
Dividend received	10,327	337	26,416	17,140
Interest paid	(227,488)	(7,429)	(107,210)	(99,857)
Income tax paid	(186,280)	(6,084)	(1,354,548)	(691,566)
Net cash generated from operating activities	6,607,482	215,789	8,616,433	7,319,709
Cash flows from investing activities
Acquisition of financial assets at amortized cost	(72,201)	(2,358)	(133,182)
Proceeds from repayments of financial assets at amortized cost	130,220	4,253	69,022	188,023
Acquisition of financial assets at fair value through other comprehensive income	(12,500)	(408)
Proceeds from disposal of financial assets at fair value through profit or loss				9,427
Acquisition of property, plant and equipment	(3,073,881)	(100,389)	(4,699,369)	(5,881,506)
Proceeds from disposal of property, plant and equipment	83,679	2,733	77,339	120,586
(Increase) decrease in refundable deposits	1,064	35	(493)	(92)
Increase in other non-current assets	(160,703)	(5,248)	(400,569)	(501,177)
Increase in long-term deferred revenue	14,145	462	25,328	49,349
Net cash used in investing activities	(3,090,177)	(100,920)	(5,061,924)	(6,015,390)
Cash flows from financing activities
Proceeds from short-term bank loans	1,273,873	41,603	348,006	2,195,726
Payments on short-term bank loans	(1,273,873)	(41,603)	(1,079,757)	(1,463,975)
Payment on lease liabilities	(293,383)	(9,581)	(237,869)	(289,668)
Proceeds from long-term bank loans	2,430,224	79,367	4,567,672	4,908,782
Payments on long-term bank loans	(1,522,918)	(49,736)	(54,000)	(3,256,450)
Decrease in guarantee deposits	(365)	(12)	(25)	(45)
Cash dividend paid	(1,672,652)	(54,626)	(3,127,133)	(1,599,928)
Net cash generated from (used in) financing activities	(1,059,094)	(34,588)	416,894	494,442
Effect of foreign exchange rate changes	(780)	(25)	19,025	(6,236)
Net increase in cash and cash equivalents	2,457,431	80,256	3,990,428	1,792,525
Cash and cash equivalents at beginning of year	9,896,604	323,207	5,906,176	4,113,651
Cash and cash equivalents at end of year	$ 12,354,035	$ 403,463	$ 9,896,604	$ 5,906,176

Corporate and group information

Corporate and group information	12 Months Ended
	Dec. 31, 2023
Disclosure of corporate and group information [abstract]
Corporate and group information	1. Corporate and group information ChipMOS TECHNOLOGIES INC. (the “Company” or “ChipMOS Taiwan”) was incorporated in the Republic of China (“ROC”) on July 28, 1997. The Company and its subsidiaries (collectively referred herein as the “Group”) are primarily engaged in the research, development, manufacturing and sale of high-integration and high-precision integrated circuits and related assembly and testing services. On April 11, 2014, the Company’s shares were listed on the Taiwan Stock Exchange (“TWSE”). On November 1, 2016, the Company’s American Depositary Shares (“ADSs”) were listed on the NASDAQ Global Select Market and traded under the ticker symbol “IMOS”.

The authorization of the consol

The authorization of the consolidated financial statements	12 Months Ended
	Dec. 31, 2023
Disclosure of authorization of the consolidated financial statements [abstract]
The authorization of the consolidated financial statements	2. The authorization of the consolidated financial statements The accompanying consolidated financial statements were authorized for issuance by the Board of Directors on April 11, 2024 .

Application of new and revised

Application of new and revised International Financial Reporting Standards, International Accounting Standards, International Financial Reporting Interpretations Committee Interpretations and Standing Interpretations Committee Interpretations issued by the International Accounting Standards Board	12 Months Ended
	Dec. 31, 2023
Disclosure of initial application of standards or interpretations [abstract]
Application of new and revised International Financial Reporting Standards ("IFRS"), International Accounting Standards ("IAS"), International Financial Reporting Interpretations Committee ("IFRIC") Interpretations and Standing Interpretations Committee ("SIC") Interpretations issued by the International Accounting Standards Board ("IASB"), (collectively, "IFRSs")	3. Application of new and revised IFRS ® Accounting Standards, International Accounting Standards (“IAS”), International Financial Reporting Interpretations Committee (“IFRIC ® ”) Interpretations and Standing Interpretations Committee (“SIC ® ”) Interpretations issued by the International Accounting Standards Board (“IASB”), (collectively, “IFRSs”) a) Amendments to IFRSs and the new interpretation that are mandatorily effective for the current year New Standards, Interpretations and Amendments Effective date issued Amendments to IAS 1, “Disclosure of Accounting Policies” January 1, 2023 Amendments to IAS 8, “Definition of Accounting Estimates” January 1, 2023 Amendments to IAS 12, “Deferred Tax related to Assets and Liabilities arising January 1, 2023 Amendments to IAS 12, “International Tax Reform–Pillar Two Model Rules” May 23, 2023 IFRS 17, “Insurance Contracts” January 1, 2023 Amendments to IFRS 17, “Insurance Contracts” January 1, 2023 Amendment to IFRS 17, “Initial Application of IFRS 17 and IFRS 9 – Comparative January 1, 2023 Based on the Group’s assessment, the above standards and interpretations have no significant impact on the Group’s financial position and financial performance. b) New standards, interpretations and amendments in issue but not yet effective New Standards, Interpretations and Amendments Effective date issued by Amendments to IFRS 16, “Lease Liability in a Sale and Leaseback” January 1, 2024 Amendments to IAS 1, “Classification of Liabilities as Current or Non-current” January 1, 2024 Amendments to IAS 1, “Non-current Liabilities with Covenants” January 1, 2024 Amendments to IAS 7 and IFRS 7, “Supplier Finance Arrangements” January 1, 2024 Amendments to IFRS 10 and IAS 28, “Sale or Contribution of Assets between To be determined by Amendments to IAS 21, “Lack of Exchangeability” January 1, 2025 Based on the Group’s assessment, the above standards and interpretations have no significant impact on the Group’s financial position and financial performance.

Summary of material accounting

Summary of material accounting policies	12 Months Ended
	Dec. 31, 2023
Summary Of Material Accounting Policies [Abstract]
Summary of material accounting policies	4. Summary of material accounting policies The principal accounting policies applied in the preparation of these accompanying consolidated financial statements are set out below. These policies have been consistently applied during the reported periods, unless otherwise stated. a) Statement of compliance The consolidated financial statements of the Group have been prepared in accordance with IFRSs as issued by the IASB. b) Basis of preparation (a) Except for the following items, the consolidated financial statements have been prepared under the historical cost convention: i) Financial assets at fair value through profit or loss (including derivative instruments). ii) Financial assets at fair value through other comprehensive income. iii) Defined benefit liabilities were recognized based on the net amount of pension fund assets less the present value of benefit obligation. (b) The preparation of the consolidated financial statements in conformity with IFRSs requires the use of certain critical accounting estimates. It also requires management to exercise its judgment in the process of applying the Group’s accounting policies. The areas involving a higher degree of judgment or complexity, or areas where assumptions and estimates are significant to the consolidated financial statements are disclosed in Note 4 dd). (c) These consolidated financial statements are presented in New Taiwan dollars (“NT$”), which is the Company’s functional currency. c) Basis of consolidation (a) Basis for preparation of consolidated financial statements: i) All subsidiaries are included in the Group’s consolidated financial statements. Subsidiaries are all entities controlled by the Group. The Group controls an entity when the Group is exposed, or has rights, to variable returns from its involvement with the entity and has the ability to affect those returns through its power over the entity. Consolidation of subsidiaries begins from the date the Group obtains control of the subsidiaries and ceases when the Group loses control of the subsidiaries. ii) Transactions, balances and unrealized gains or losses on transactions between companies within the Group are eliminated. Accounting policies of subsidiaries have been adjusted where necessary to ensure consistency with the policies adopted by the Group. iii) Profit or loss and each component of other comprehensive income are attributed to the owners of the parent and to the non-controlling interests. Total comprehensive income is attributed to the owners of the parent and to the non-controlling interests even if this results in a deficit balance in the non-controlling interests. iv) Changes in a parent’s ownership interest in a subsidiary that do not result in the parent losing control of the subsidiary (transactions with non-controlling interests) are accounted for as equity transactions, i.e. transactions with owners in their capacity as owners. Any difference between the amount by which the non-controlling interests are adjusted and the fair value of the consideration paid or received is recognized directly in equity. v) When the Group loses control of a subsidiary, the Group remeasures any investment retained in the former subsidiary at its fair value. That fair value is regarded as the fair value on initial recognition of a financial asset or the cost on initial recognition of the associate or joint venture. Any difference between fair value and carrying amount is recognized in profit or loss. All amounts previously recognized in other comprehensive income in relation to the subsidiary are reclassified to profit or loss on the same basis as would be required if the related assets or liabilities were disposed of. That is, when the Group loses control of a subsidiary, all gains or losses previously recognized in other comprehensive income in relation to the subsidiary should be reclassified from equity to profit or loss, if such gains or losses would be reclassified to profit or loss when the related assets or liabilities are disposed of. (b) Subsidiaries included in the consolidated financial statements: Percentage of December 31, Name of investor Name of investee Main business Location 2022 2023 The Company ChipMOS U.S.A., Inc. (“ChipMOS USA”) Marketing of semiconductors and electronic related products San Jose, USA 100 100 The Company ChipMOS TECHNOLOGIES (BVI) LTD. (“ChipMOS BVI”) Holding company British Virgin Islands 100 100 ChipMOS BVI ChipMOS SEMICONDUCTORS (Shanghai) LTD. (“ChipMOS Shanghai”) Marketing of semiconductors and electronic related products Shanghai, People’s Republic of China (“PRC”) 100 100 (c) Subsidiaries not included in the consolidated financial statements: None. (d) Adjustments for subsidiaries with different statements of financial position dates: Not applicable. (e) No significant restrictions on the ability of subsidiaries to transfer funds to parent company. (f) Subsidiaries that have non-controlling interests that are material to the Group: None. d) Foreign currency translation Items included in the financial statements of each of the Group’s entities are measured using the currency of the primary economic environment in which the entity operates (the “functional currency”). The consolidated financial statements are presented in NT$, which is the Company’s functional currency and the Group’s presentation currency. (a) Foreign currency transactions and balances i) Foreign currency transactions are translated into the functional currency using the exchange rates on the trade date or measurement date. Therefore, foreign exchange differences resulting from the settlement of such transactions are recognized in profit or loss in the period in which they arise. ii) Monetary assets and liabilities denominated in foreign currencies at the period end are re-translated at the exchange rates prevailing at the statements of financial position date. Exchange differences arising upon re-translation are recognized in profit or loss on the statements of financial position date. iii) Non-monetary assets and liabilities denominated in foreign currencies held at fair value through profit or loss are re-translated at the exchange rates prevailing at the statements of financial position date; their exchange differences are recognized in profit or loss. Non-monetary assets and liabilities denominated in foreign currencies held at fair value through other comprehensive income are re-translated at the exchange rates prevailing at the statements of financial position date; their exchange differences are recognized in other comprehensive income. However, non-monetary assets and liabilities denominated in foreign currencies that are not measured at fair value are translated using the historical exchange rates at the initial dates of the transactions. iv) All foreign exchange differences are presented in the statement of comprehensive income under “Other gains and losses” by the nature of transactions. (b) Translation of foreign operations The operating results and financial position of all the group entities, associates that have different functional currency and presentation currency are translated into the presentation currency as follows: i) Assets and liabilities for each statements of financial position are translated at the exchange rates prevailing at the statements of financial position date; ii) Income and expenses for each statement of comprehensive income are translated at average exchange rates of that period; and iii) All exchange differences are recognized in other comprehensive income. e) Classification of current and non-current assets and liabilities (a) Assets that meet one of the following criteria are classified as current assets: i) Assets arising from operating activities that are expected to be realized, or are intended to be sold or consumed within the normal operating cycle; ii) Assets held mainly for trading purposes; iii) Assets that are expected to be realized within 12 months from the statements of financial position date; iv) Cash and cash equivalents, excluding restricted cash and cash equivalents and those that are to be exchanged or used to pay off liabilities more than 12 months after the statements of financial position date. All assets that do not meet the above criteria are classified as non-current assets. (b) Liabilities that meet one of the following criteria are classified as current liabilities: i) Liabilities that are expected to be settled within the normal operating cycle; ii) Liabilities arising mainly from trading activities; iii) Liabilities that are to be settled within 12 months from the statements of financial position date; iv) Liabilities for which the repayment date cannot be unconditionally extended to more than 12 months after the statements of financial position date. Liabilities bearing terms that could, at the option of the counterparty, result in its settlement by the issue of equity instruments do not affect its classification. All liabilities that do not meet the above criteria are classified as non-current liabilities. f) Cash equivalents Cash equivalents refer to short-term, highly liquid investments that are readily convertible to known amounts of cash and are subject to an insignificant risk of changes in value (including time deposits with less than 3 months contract period). Time deposits that meet the above definition and are held for the purpose of meeting short-term cash commitments in operations are classified as cash equivalents. g) Financial assets at fair value through profit or loss (a) Financial assets at fair value through profit or loss are financial assets that are not measured at amortized cost or fair value through other comprehensive income. (b) On a regular way purchase or sale basis, financial assets at fair value through profit or loss are recognized and derecognized using settlement date accounting. (c) At initial recognition, the Group measures the financial assets at fair value and recognizes the transaction costs in profit or loss. The Group subsequently measures the financial assets at fair value, and recognizes the gain or loss in profit or loss. (d) The Group recognizes the dividend income when the right to receive such payment is confirmed, inflow of the future economic benefits associated with the dividend is probable to the Group and the amount of the dividend can be measured reliably. h) Financial assets at fair value through other comprehensive income (a) Financial assets at fair value through other comprehensive income comprise equity instruments which are not held for trading, and for which the Group has made an irrevocable election at initial recognition to recognize changes in fair value in other comprehensive income. (b) On a regular way purchase or sale basis, financial assets at fair value through other comprehensive income are recognized and derecognized using settlement date accounting. (c) At initial recognition, the Group measures the financial assets at fair value plus transaction costs. The Group subsequently measures the financial assets at fair value: The changes in fair value of equity instruments that were recognized in other comprehensive income are reclassified to retained earnings and are not reclassified to profit or loss following the derecognition of the investment. Dividends are recognized as income when the right to receive such payment is confirmed, inflow of the future economic benefits associated with the dividend is probable to the Group and the amount of the dividend can be measured reliably. i) Financial assets at amortized cost (a) Financial assets at amortized cost are those that meet all of the following criteria: i) The objective of the Group’s business model is achieved by collecting contractual cash flows. ii) The financial assets’ contractual cash flows represent solely payments of principal and interest. (b) The Group’s time deposits which do not fall under cash equivalents are those with a short maturity period and are measured at initial investment amount as the effect of discounting is immaterial. j) Accounts receivable (a) Accounts receivable entitle the Group a legal right to receive consideration in exchange for transferred goods or rendered services. (b) The short-term accounts receivable without bearing interest are subsequently measured at initial invoice amount as the effect of discounting is immaterial. k) Impairment of financial assets For financial assets at amortized cost, at each reporting date, the Group recognizes the impairment provision for 12 months expected credit losses if there has not been a significant increase in credit risk since initial recognition or recognizes the impairment provision for the lifetime expected credit losses if such credit risk has increased since initial recognition after taking into consideration all reasonable and verifiable information that includes forecasts. On the other hand, for accounts receivable or contract assets that do not contain a significant financing component, the Group recognizes the impairment provision for lifetime expected credit losses. l) Derecognition of financial assets The Group derecognizes a financial asset when the contractual rights to receive the cash flows from the financial asset have expired. m) Inventories Inventories are initially recorded at standard costs. Cost is determined on a weighted-average cost basis. At the end of reporting period, the differences between actual costs and standard costs were allocated to inventories and cost of revenue based on an appropriate rate. Allocation of fixed production overheads is based on the normal operating capacity of the production facilities. Costs associated with underutilized capacity are expensed in the period that the cost occurs. Inventories are valued at the lower of cost and net realizable value. Net realizable value is the estimated selling price in the ordinary course of business less the estimated costs of completion and the estimated costs necessary to make the sale. The item by item approach is used in raw materials. The amount of any write-down of inventories to net realizable value and all losses of inventories are recognized as an expense in the period the write-down or loss occurs. n) Non-current assets held for sale Non-current assets are classified as assets held for sale when their carrying amount is to be recovered principally through a sale transaction rather than through continuing use, and a sale is considered highly probable. They are stated at the lower of carrying amount and fair value less costs to sell. o) Investments accounted for using equity method – associates (a) Associates are all entities over which the Group has significant influence but not control. In general, it is presumed that the investor has significant influence, if an investor holds, directly or indirectly 20 percent or more of the voting power of the investee. Investments in associates are accounted for using the equity method and are initially recognized at cost. (b) The Group’s share of its associates’ post-acquisition profits or losses is recognized in profit or loss, and its share of post-acquisition movements in other comprehensive income is recognized in other comprehensive income. When the Group’s share of losses in an associate equals or exceeds its interests in the associate, including any other unsecured receivables, the Group does not recognize further losses, unless it has incurred legal or constructive obligations or made payments on behalf of the associate. (c) When changes in an associate’s equity that are not recognized in profit or loss or other comprehensive income of the associate and such changes not affecting the Group’s ownership percentage of the associate, the Group recognizes the Group’s share of change in equity of the associate in “Capital surplus” in proportion to its ownership. (d) Unrealized gains on transactions between the Group and its associates are eliminated to the extent of the Group’s interests in the associates. Unrealized losses are also eliminated unless the transaction provides evidence of an impairment of the asset transferred. Accounting policies of associates have been adjusted where necessary to ensure consistency with the policies adopted by the Group. (e) In the case where an associate issues new shares and the Group does not subscribe or proportionately acquire the new shares, which results in a change in the Group’s ownership percentage of the associate while maintaining significant influence on the associate, then the Group will treat the transaction as deemed disposal and reclassify to profit or loss the proportion of the gain or loss previously recognized in other comprehensive income relating to that reduction in ownership interest where appropriate. (f) When the Group disposes of its investment in an associate, if it loses significant influence on this associate, the amounts previously recognized in other comprehensive income in relation to the associate are reclassified to profit or loss, on the same basis as would be required if the relevant assets or liabilities were disposed of. If it still retains significant influence on this associate, then the amounts previously recognized in other comprehensive income in relation to the associate are reclassified to profit or loss proportionately in accordance with the aforementioned approach. p) Property, plant and equipment (a) Property, plant and equipment are initially recorded at cost. Borrowing costs incurred during the construction period are capitalized. (b) Subsequent costs are included in the asset’s carrying amount or recognized as a separate asset, as appropriate, only when it is probable that future economic benefits associated with the item will flow to the Group and the cost of the item can be measured reliably. The carrying amount of the replaced part is derecognized. All other repairs and maintenance are charged to profit or loss during the financial period in which they are incurred. (c) Land is not depreciated. Other property, plant and equipment apply cost model and are depreciated using the straight-line method to allocate their cost over their estimated useful lives. Each part of an item of property, plant and equipment with a cost that is significant in relation to the total cost of the item must be depreciated separately. (d) The assets’ residual values, useful lives and depreciation methods are reviewed, and adjusted if appropriate, at each financial year-end. If expectations for the assets’ residual values and useful lives differ from previous estimates or the patterns of consumption of the assets’ future economic benefits embodied in the assets have changed significantly, any change is accounted for as a change in estimate under IAS 8, “Accounting Policies, Change in Accounting Estimates and Errors”, from the date of the change. The estimated u seful lives of property, plant and equipment are as follows: Buildings 1 to 51 years Machinery and equipment 1 to 20 years Tools 1 to 4 years Others 1 to 7 years q) Leasing arrangements (lessee) – right-of-use assets / lease liabilities (a) Leases are recognized as a right-of-use asset and a corresponding lease liability at the date at which the leased asset is available for use by the Group. For short-term leases or leases of low value assets, lease payments are recognized as an expense on a straight-line basis over the lease term. (b) Lease liabilities include the net present value of the remaining lease payments at the commencement date, discounted using the incremental borrowing interest rate. Lease payments are comprised of the following: i) Fixed payments, less any lease incentives receivable; ii) The exercise price of a purchase option, if the lessee is reasonably certain to exercise that option. The Group subsequently measures the lease liability at amortized cost using the interest method and recognizes interest expense over the lease term. The lease liability is remeasured and the amount of remeasurement is recognized as an adjustment to the right-of-use asset when there are changes in the lease term or lease payments and such changes do not arise from contract modifications. (c) At the commencement date, the right-of-use asset is stated at the amount of the initial measurement of lease liability. The right-of-use asset is measured subsequently using the cost model and is depreciated from the commencement date to the earlier of the end of the asset’s useful life or the end of the lease term. When the lease liability is remeasured, the amount of remeasurement is recognized as an adjustment to the right-of-use asset. r) Impairment of non-financial assets The Group assesses at each statements of financial position date the recoverable amounts of those assets where there is an indication that they are impaired. An impairment loss is recognized for the amount by which the asset’s carrying amount exceeds its recoverable amount. The recoverable amount is the higher of an asset’s fair value less costs to sell or value in use. When the circumstances or reasons for recognizing impairment loss for an asset in prior years no longer exist or diminish, the impairment loss is reversed. The increased carrying amount due to reversal should not be more than what the depreciated or amortized historical cost would have been if the impairment had not been recognized. s) Loans Loans comprise long-term and short-term bank loans. Loans are recognized initially at fair value, net of transaction costs incurred. Loans are subsequently stated at amortized cost; any difference between the proceeds (net of transaction costs) and the redemption value is recognized as interest expense in profit or loss over the period of the loans using the effective interest method. t) Accounts and notes payable (a) Accounts payable are liabilities for purchases of raw materials, goods or services and notes payable are those resulting from operating and non-operating activities. (b) The short-term accounts and notes payable without bearing interest are subsequently measured at initial invoice amount as the effect of discounting is immaterial. u) Derecognition of financial liabilities A financial liability is derecognized when the obligation specified in the contract is either discharged or cancelled or expires. v) Provisions for deficiency compensation Provisions are recognized when the Group has a present legal or constructive obligation as a result of past events, and it is probable that an outflow of economic resources will be required to settle the obligation and the amount of the obligation can be reliably estimated. Provisions are measured at the present value of the expenditures expected to be required to settle the obligation on the statements of financial position date, which is discounted using a pre-tax discount rate that reflects the current market assessments of the time value of money and the risks specific to the obligation. When discounting is used, the increase in the provision arising from the passage of time is recognized as interest expense. Provisions are not recognized for future operating losses . w) Employee benefits (a) Short-term employee benefits Short-term employee benefits are measured at the undiscounted amount of the benefits expected to be paid in respect of service rendered by employees and should be recognized as expenses when the employees render service. (b) Pensions i) Defined contribution plans For defined contribution plans, the contributions are recognized as pension expenses when they are due on an accrual basis. Prepaid contributions are recognized as an asset to the extent of a cash refund or a reduction in future payments. ii) Defined benefit plans 1. Net obligation under a defined benefit plan is defined as the present value of an amount of pension benefits that employees will receive on retirement for their services with the Group in the current period or prior periods. The liability recognized in the statements of financial position in respect of defined benefit pension plans is the present value of the defined benefit obligation at the statements of financial position date less the fair value of plan assets. The net defined benefit obligation is calculated annually by independent actuaries using the projected unit credit method. The discount rate is determined by using the interest rates of government bonds that are denominated in the currency in which the benefits will be paid, and that have terms to maturity approximating to the terms of the related pension liability. 2. Remeasurements arising on defined benefit plans are recognized in other comprehensive income in the period in which they arise and are recorded as retained earnings. 3. Past service costs are recognized immediately in profit or loss. (c) Termination benefits Termination benefits are employee benefits provided in exchange for the termination of employment as a result from either the Group’s decision to terminate an employee’s employment before the normal retirement date, or an employee’s decision to accept an offer of redundancy benefits in exchange for the termination of employment. The Group recognizes an expense as it can no longer withdraw an offer of termination benefits, or it recognizes related restructuring costs, whichever is earlier. Benefits that are expected to be due more than 12 months after statements of financial position date shall be discounted to their present value. (d) Employees’ compensation and directors’ remuneration Employees’ compensation and directors’ remuneration are recognized as expenses and liabilities, provided that such recognition is required under legal obligation or constructive obligation and those amounts can be reliably estimated. Any difference between the resolved amounts and the subsequently actual distributed amounts is accounted for as changes in estimates. If employee compensation is paid by shares, the Company calculates the number of shares based on the closing price at the previous day of the board meeting resolution. x) Income tax (a) The income tax expense for the period comprises current and deferred tax. Income tax is recognized in profit or loss, except to the extent that it relates to items recognized in other comprehensive income or items recognized directly in equity, in which cases the income tax is recognized in other comprehensive income or equity. (b) The current income tax expense is calculated on the basis of the tax laws enacted or substantively enacted at the statements of financial position date in the countries where the Group and its subsidiaries operate and generate taxable income. Management periodically evaluates positions taken in tax returns with respect to situations in accordance with applicable tax regulations. It establishes provisions where appropriate based on the amounts expected to be paid to the tax authorities. An additional income tax is levied on the unappropriated retained earnings and is recorded as income tax expense in the year the profit generated. (c) Deferred tax is recognized, using the balance sheet liability method, on temporary differences arising between the tax bases of assets and liabilities and their carrying amounts in the consolidated statements of financial position. However, the deferred tax is not accounted for if it arises from initial recognition of an asset or liability in a transaction other than a business combination that at the time of the transaction affects neither accounting nor taxable profit or loss. Deferred tax is provided on temporary differences arising on investments in subsidiaries and associates, except where the timing of the reversal of the temporary difference is controlled by the Group and it is probable that the temporary difference will not reverse in the foreseeable future. Deferred tax is determined using tax rates (and laws) that have been enacted or substantially enacted at the statements of financial position date and are expected to apply when the related deferred tax asset is realized or the deferred tax liability is settled. (d) Deferred tax assets are recognized only to the extent that it is probable that future taxable profit will be available against which the temporary differences can be utilized. At each statements of financial position date, unrecognized and recognized deferred tax assets are reassessed. (e) A deferred tax asset shall be recognized for the carryforward of unused tax credits resulting from equity investments to the extent that it is possible that future taxable profit will be available against which the unused tax credits can be utilized. (f) If a change in tax rate is enacted or substantively enacted, the Group recognizes the effect of the change immediately in the period in which the change occurs. The effect of the change on items recognized outside profit or loss is recognized in other comprehensive income or equity while the effect of the change on items recognized in profit or loss is recognized in profit or loss. y) Capital stock (a) Ordinary shares are classified as equity. Incremental costs directly attributable to the issue of new shares in net proceeds of tax are shown in equity as a deduction. (b) Where the Company repurchases the Company’s shares that have been issued, the consideration paid, including any directly attributable incremental costs (net of income taxes) is deducted from equity attributable to the Company’s equity holders. Where such shares are subsequently reissued, the difference between their book value and any consideration received, net of any directly attributable incremental transaction costs and the related income tax effects, is included in equity attributable to the Company’s equity holders. z) Dividends Dividends are recorded in the Company’s financial statements in the period in which they are resolved by the Company’s shareholders. Cash dividends are recorded as liabilities; stock dividends are recorded as stock dividends to be distributed and are reclassified to ordinary shares on the effective date of new shares issuance. aa) Revenue recognition (a) The Group is primarily engaged in the customized assembly and testing services of high-integration and high-precision integrated circuits based on customer’s specification demand to create or enhance the product. When providing assembly and testing services, the Group considers: i) Customer controls the provided raw materials and the Group receives the instruction from the customer on providing assembly and testing services and subsequent treatments. ii) The Group provides assembly and testing services to create or enhance an asset which is solely provided and controlled by the customer. The Group has no right to transfer the asset for another use. As the asset ownership belongs to the customer, who bears the significant risk and rewards and rights on the use of the asset, the Group recognizes assembly and testing service revenue based on the progress towards completion of performance obligation during the service period. (b) The progress towards completion on Assembly services, services for Display panel driver semiconductor assembly and testing (“LCDD”) and Bumping are measured by the actual input costs relative to estimate total expected input costs. The progress towards completion on testing services is measured by the actual incurred testing volume. The Group provides assembly and testing services based on customer’s specification, thus, the input costs incurred to assembly and testing volume completed in testing services are not linear over the duration of these services. Customer payment on assembly and testing services is based on predetermined payment schedule. A contract asset is recognized when the Group provides services in excess of customer’s payment. bb) Government grants Government grants are recognized at their fair value only when there is reasonable assurance that the Group will comply with any conditions attached to the grants will be received. Government grants are recognized in profit or loss on a systematic basis over the periods in which the Group recognizes expenses for the related costs for which the grants are intended to compensate. Government grants related to property, plant and equipment are recognized as non-current liabilities and are amortized to profit or loss over the estimated useful lives of the related assets using straight-line method. cc) Operating segments Operating segments are reported in a manner consistent with the internal reporting provided to the chief operating decision maker. The Group’s chief operating decision maker, who is responsible for allocating resources and assessing performance of the operating segments

Translation into U.S. dollar am

Translation into U.S. dollar amounts	12 Months Ended
	Dec. 31, 2023
Translation into U S dollar amounts [abstract]
Translation into U.S. dollar amounts	5. Translation into U.S. dollar amounts The Company maintains its accounts and expresses its consolidated financial statements in New Taiwan dollars. For convenience purposes, U.S. dollar amounts presented in the accompanying consolidated financial statements have been translated from New Taiwan dollars to U.S. dollars at the noon buying rate in the City of New York for cable transfers as certified for customs purposes by the Federal Reserve Bank of New York as of December 29, 2023 , which was NT$ 30.62 to US$1.00. These convenience translations should not be construed as representations that the New Taiwan dollar amounts have been, or could in the future be, converted into U.S. dollars at this or any other rate of exchange.

Cash and cash equivalents

Cash and cash equivalents	12 Months Ended
	Dec. 31, 2023
Cash and cash equivalents [abstract]
Cash and cash equivalents	6. Cash and cash equivalents December 31, 2022 December 31, 2023 NT$000 NT$000 Cash on hand and petty cash 450 450 Checking accounts and demand deposits 2,248,954 1,434,939 Time deposits 7,647,200 10,918,646 9,896,604 12,354,035 a) The Group transacts with a variety of financial institutions all with high credit quality to disperse credit risk, so it expects that the probability of counterparty default is remote. b) No cash and cash equivalents of the Group were pledged to others.

Financial assets at fair value

Financial assets at fair value through profit or loss	12 Months Ended
	Dec. 31, 2023
Financial assets at fair value through profit or loss [abstract]
Financial assets at fair value through profit or loss	7. Financial assets at fair value through profit or loss December 31, 2022 December 31, 2023 NT$000 NT$000 Current: Financial assets mandatorily measured at fair value Listed stocks 171,988 53,747 Valuation adjustment ( 43,764 ) ( 11,012 ) 128,224 42,735 a) Amounts recognized in profit or loss in relation to the financial assets at fair value through profit or loss are listed below: Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Financial assets mandatorily measured at fair value Listed stocks 13,673 ( 75,211 ) 22,001 Beneficiary certificates* 2,530 5,807 17,253 Foreign partnership interests ( 941 ) — — 15,262 ( 69,404 ) 39,254 * Beneficiary certificates represent money market funds the Company held during the reporting period. As of December 31, 2021, 2022 and 2023, there were no beneficiary certificates classified as current financial assets at fair value through profit or loss (“FVTPL”). b) No financial assets at FVTPL were pledged to others. c) I nformation relating to price risk of financial assets at FVTPL is provided in Note 41 a).

Financial assets at amortized c

Financial assets at amortized cost	12 Months Ended
	Dec. 31, 2023
Financial assets at amortized cost [Abstract]
Financial assets at amortized cost	8. Financial assets at amortized cost December 31, 2022 December 31, 2023 NT$000 NT$000 Current: Time deposits 98,731 41,066 Non-current: Restricted bank deposits 37,362 37,411 a) Amounts recognized in profit or loss in relation to financial assets at amortized cost are listed below: Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Interest income 1,187 587 1,861 b) Without taking into account any collateral held or other credit enhancements, the maximum exposure to credit risk in respect of the amount that best represents the financial assets at amortized cost held by the Group is the carrying amount at the end of each reporting period. c) Information about the financial assets at amortized cost that were pledged to others as collateral is provided in Note 36. d) Information relating to credit risk of financial assets at amortized cost is provided in Note 41 a).

Accounts receivable

Accounts receivable	12 Months Ended
	Dec. 31, 2023
Accounts Receivable [Abstract]
Accounts receivable	9. Accounts receivable December 31, 2022 December 31, 2023 NT$000 NT$000 Accounts receivable 4,384,232 5,328,835 Less: Loss allowance ( 2,669 ) ( 2,454 ) 4,381,563 5,326,381 a) The Group’s credit term granted to customers is 30 ~ 90 days. Receivables do not bear interest. The loss allowance is determined based on the credit quality of customers. Information relating to credit risk is provided in Note 41 a). b) The aging analysis of accounts receivable based on past due date are as follows: December 31, 2022 December 31, 2023 NT$000 NT$000 Current 4,357,073 5,326,523 Within 1 month 27,159 2,089 1-2 months — 223 4,384,232 5,328,835 c) As of December 31, 2022 and 2023, accounts receivable were all from contracts with customers. And as of January 1, 2022, the balance of accounts receivable from contracts with customers was NT$ 6,344,246 thousand. d) Without taking into account of any collateral held or other credit enhancements, the amount that best reflects the Group’s maximum exposure to credit risk in respect of the accounts receivable is the carrying amount at the end of each reporting period. e) No accounts receivable of the Group were pledged to others.

Inventories

Inventories	12 Months Ended
	Dec. 31, 2023
Inventories [abstract]
Inventories	10. Inventories December 31, 2022 Cost Allowance for Carrying amount NT$000 NT$000 NT$000 Raw materials 3,316,039 ( 105,630 ) 3,210,409 December 31, 2023 Cost Allowance for Carrying amount NT$000 NT$000 NT$000 Raw materials 2,754,911 ( 186,263 ) 2,568,648 The cost of inventories recognized as an expense for the year: Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Cost of revenue 20,103,735 18,611,515 17,723,687 Loss on abandonment 552 9,448 2,483 Allowance for (reversal of) inventory 41,770 ( 15,956 ) 80,633 20,146,057 18,605,007 17,806,803 a) Allowance for inventory valuation and obsolescence loss was recognized due to the change in net realizable value. b) No inventories of the Group were pledged to others.

Non-current financial assets at

Non-current financial assets at fair value through other comprehensive income	12 Months Ended
	Dec. 31, 2023
Non-current financial assets at fair value through other comprehensive income [abstract]
Non-current financial assets at fair value through other comprehensive income	11. Non-current financial assets at fair value through other comprehensive income December 31, 2022 December 31, 2023 NT$000 NT$000 Designation of equity instruments Foreign unlisted stocks 38,534 38,534 Valuation adjustment 299,568 81,783 338,102 120,317 a) Based on the Group’s business model, the foreign unlisted stocks held for strategic investments were elected to classify as Financial assets at fair value through other comprehensive income. As of December 31, 2022 and 2023, the fair value of aforementioned investments is the carrying amount at the end of each reporting period. b) Amounts recognized in other comprehensive income in relation to the financial assets at fair value through other comprehensive income are listed below: Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Financial assets at fair value through other Foreign unlisted stocks 122,514 ( 46,419 ) ( 217,785 ) c) No financial assets at fair value through other comprehensive income were pledged to others. d) In April 2023, the Company acquired 1,000 thousand ordinary shares of Daypower Energy Co., Ltd. (“Daypower Energy”) in the amount of NT$ 12,500 thousand, representing 10 % of shareholding and was recorded as financial assets at fair value through other comprehensive income. Subsequently, in August 2023, the Company participated in the re-election of the directors of Daypower Energy and obtained significant influence by holding one seat in Daypower Energy’s Board of Directors. As a result, the Company reclassified the investment as investment accounted for using equity method from financial assets at fair value through other comprehensive income. Information related to Daypower Energy investment is provided in Note 12. e) Information about fair value measurement is provided in N ote 41 b).

Investments accounted for using

Investments accounted for using equity method	12 Months Ended
	Dec. 31, 2023
Investments accounted for using equity method [abstract]
Investments accounted for using equity method	12. Investments accounted for using equity method Associates December 31, 2022 December 31, 2023 NT$000 NT$000 JMC ELECTRONICS CO., LTD. (“JMC”) 267,070 277,076 Unimos Microelectronics (Shanghai) Co., Ltd. 4,086,378 — Daypower Energy — 13,466 4,353,448 290,542 Note: On December 21, 2023, the Company's Board of Directors approved its subsidiary ChipMOS BVI to sell the investment accounted for using equity method in Unimos Shanghai and reclassified the investment as non-current assets held for sale. Information relating to non-current assets held for sale is provided in Note 14. a) The carrying amount of the Group’s interests in all individually immaterial associates and the Group’s share of the operating results are summarized below: As of December 31, 2022 and 2023 , the carrying amount of the Group’s individually immaterial associates amounted to NT$ 4,353,448 thousand and NT$ 290,542 thousand, respectively. Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Profit for the year from continuing operations 625,733 453,715 1,714 Other comprehensive income (loss), net of income tax 28,843 ( 28,254 ) 12,993 Total comprehensive income 654,576 425,461 14,707 b) JMC has quoted market prices. As of December 31, 2022 and 2023 , the fair value was NT$ 249,000 thousand and NT$ 303,780 thousand, respectively . c) Both JMC and Daypower Energy are recognized as investment accounted for using equity method given that the Company retains significant influence by holding one seat in JMC’s and Daypower Energy’s Board of Directors.

Property, plant and equipment,

Property, plant and equipment, net	12 Months Ended
	Dec. 31, 2023
Disclosure of detailed information about property, plant and equipment [abstract]
Property, plant and equipment, net	13. Property, plant and equipment, net 2021 Land Buildings Machinery Tools Others Construction in Total NT$000 NT$000 NT$000 NT$000 NT$000 NT$000 NT$000 January 1 Cost 452,738 11,212,129 53,246,474 5,451,547 2,185,299 639,607 73,187,794 Accumulated depreciation — ( 7,119,843 ) ( 41,898,177 ) ( 4,499,186 ) ( 1,675,902 ) — ( 55,193,108 ) 452,738 4,092,286 11,348,297 952,361 509,397 639,607 17,994,686 January 1 452,738 4,092,286 11,348,297 952,361 509,397 639,607 17,994,686 Additions — 1,345 11,829 407 189 6,538,932 6,552,702 Disposals — — ( 66,873 ) ( 9,502 ) — — ( 76,375 ) Reclassifications — 673,208 4,890,400 690,346 241,656 ( 6,495,610 ) — Depreciation expenses — ( 423,283 ) ( 2,896,612 ) ( 795,622 ) ( 239,515 ) — ( 4,355,032 ) Impairment losses — — ( 4,843 ) — — — ( 4,843 ) Exchange adjustment — — ( 13 ) — ( 4 ) — ( 17 ) December 31 452,738 4,343,556 13,282,185 837,990 511,723 682,929 20,111,121 December 31 Cost 452,738 11,877,419 57,176,339 5,574,316 2,345,204 682,929 78,108,945 Accumulated depreciation — ( 7,533,863 ) ( 43,894,154 ) ( 4,736,326 ) ( 1,833,481 ) — ( 57,997,824 ) 452,738 4,343,556 13,282,185 837,990 511,723 682,929 20,111,121 2022 Land Buildings Machinery Tools Others Construction in Total NT$000 NT$000 NT$000 NT$000 NT$000 NT$000 NT$000 January 1 Cost 452,738 11,877,419 57,176,339 5,574,316 2,345,204 682,929 78,108,945 Accumulated depreciation — ( 7,533,863 ) ( 43,894,154 ) ( 4,736,326 ) ( 1,833,481 ) — ( 57,997,824 ) 452,738 4,343,556 13,282,185 837,990 511,723 682,929 20,111,121 January 1 452,738 4,343,556 13,282,185 837,990 511,723 682,929 20,111,121 Additions — 3,780 6,748 636 — 4,907,318 4,918,482 Disposals — — ( 46,084 ) ( 2,597 ) — — ( 48,681 ) Reclassifications — 1,503,432 2,603,381 685,481 294,765 ( 5,086,047 ) 1,012 Depreciation expenses — ( 465,260 ) ( 3,075,191 ) ( 724,813 ) ( 257,817 ) — ( 4,523,081 ) Impairment losses — — ( 12,721 ) — — — ( 12,721 ) Exchange adjustment — — 50 — 23 — 73 December 31 452,738 5,385,508 12,758,368 796,697 548,694 504,200 20,446,205 December 31 Cost 452,738 13,379,852 59,197,255 5,716,357 2,615,959 504,200 81,866,361 Accumulated depreciation — ( 7,994,344 ) ( 46,438,887 ) ( 4,919,660 ) ( 2,067,265 ) — ( 61,420,156 ) 452,738 5,385,508 12,758,368 796,697 548,694 504,200 20,446,205 2023 Land Buildings Machinery Tools Others Construction in Total NT$000 NT$000 NT$000 NT$000 NT$000 NT$000 NT$000 January 1 Cost 452,738 13,379,852 59,197,255 5,716,357 2,615,959 504,200 81,866,361 Accumulated depreciation — ( 7,994,344 ) ( 46,438,887 ) ( 4,919,660 ) ( 2,067,265 ) — ( 61,420,156 ) 452,738 5,385,508 12,758,368 796,697 548,694 504,200 20,446,205 January 1 452,738 5,385,508 12,758,368 796,697 548,694 504,200 20,446,205 Additions — 1,303 5,579 291 1,376 3,219,922 3,228,471 Disposals — — ( 16,574 ) ( 11,038 ) — — ( 27,612 ) Reclassifications 2,000 469,597 1,787,140 586,090 226,610 ( 3,071,437 ) — Depreciation expenses — ( 557,187 ) ( 3,043,504 ) ( 635,227 ) ( 262,388 ) — ( 4,498,306 ) Impairment losses — — ( 9,236 ) — — — ( 9,236 ) Exchange adjustment — — — — ( 19 ) — ( 19 ) December 31 454,738 5,299,221 11,481,773 736,813 514,273 652,685 19,139,503 December 31 Cost 454,738 13,850,418 60,650,428 5,959,251 2,774,055 652,685 84,341,575 Accumulated depreciation — ( 8,551,197 ) ( 49,168,655 ) ( 5,222,438 ) ( 2,259,782 ) — ( 65,202,072 ) 454,738 5,299,221 11,481,773 736,813 514,273 652,685 19,139,503 a) Amount of borrowing costs capitalized as part of property, plant and equipment and the range of the interest rates for such capitalization are as follows: Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Amount of interest capitalized 11,193 10,856 7,692 Range of the interest rates for capitalization 1.1358 % 1.0094 % 1.4588 % b) Information about the property, plant and equipment that were pledged to others as collaterals is provided in Note 36.

Non-current assets held for sal

Non-current assets held for sale	12 Months Ended
	Dec. 31, 2023
Non-current assets held for sale	14. Non-current assets held for sale On December 21, 2023, the Company's Board of Directors approved its subsidiary ChipMOS BVI to sell the 45.0242 % owned equity investment accounted for using equity method in Unimos Shanghai to Suzhou Oriza PuHua Zhixin Equity Investment Partnership (L.P.) and other local Chinese investment management companies. Therefore, the investment accounted for using equity method of Unimos Shanghai have been reclassified as non-current assets held for sale at the carrying amount. The equity transfer is expected to be completed in the first half of 2024. a) Assets held for sale: December 31, 2023 NT$000 Investment accounted for using equity method in 4,278,658 b) Information relating to cumulative income or expense recognized in other comprehensive income relating to disposal assets classified as held for sale is provided in Note 22.

Leasing arrangements - leasee

Leasing arrangements - leasee	12 Months Ended
	Dec. 31, 2023
Presentation of leases for lessee [abstract]
Leasing arrangements - leasee	15. Leasing arrangements – lessee a) The Group leases various assets, including land, buildings, machinery and equipment, and others. Lease contracts are typically made for periods of 2 to 30 years. For machinery and equipment, lease contracts are between 2 to 3 years. For land, lease contracts are between 10 to 30 years. Lease terms are negotiated on an individual basis and contain a wide range of different terms and conditions. The lease contracts do not impose covenants, but leased assets may not be used as security for borrowing purposes. b) The carrying amount of right-of-use assets and the depreciation expenses are as follows: Carrying amount December 31, 2022 December 31, 2023 NT$000 NT$000 Land 630,969 615,385 Buildings 8,214 7,723 Machinery and equipment 257,196 411,809 Others 2,613 2,585 898,992 1,037,502 Depreciation expenses Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Land 20,486 21,904 21,524 Buildings 9,870 10,861 11,738 Machinery and equipment 247,090 194,059 245,304 Others 1,634 1,997 2,461 279,080 228,821 281,027 c) For the years ended December 31, 2022 and 2023 , additions to right-of-use assets were NT$ 308,550 thousand and NT$ 419,625 thousand, respectively. d) The information on profit or loss a ccounts relating to lease contracts is as follows: Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Items affecting profit or loss Interest expense on lease liabilities 15,245 14,556 18,757 Expense on short-term lease contracts 143,791 95,213 55,944 e) For the years ended December 31, 2021, 2022 and 2023 , the Group’s total cash outflow for leases were NT$ 448,290 thousand, NT$ 333,133 thousand and NT$ 351,063 thousan d, respectively.

Other Payables

Other Payables	12 Months Ended
	Dec. 31, 2023
Trade and other current payables [abstract]
Other Payables	16. Other payables December 31, 2022 December 31, 2023 NT$000 NT$000 Payable to equipment suppliers 1,405,931 1,196,181 Salaries and bonuses payable 1,002,577 994,651 Employees’ compensation payable 447,303 250,181 Pension payable 16,541 16,825 Directors’ remuneration payable 11,182 6,255 Interest payable 7,768 9,625 Other expense payable 905,179 1,005,327 3,796,481 3,479,045

Long-term bank loans

Long-term bank loans	12 Months Ended
	Dec. 31, 2023
Borrowings [abstract]
Long-term bank loans	17. Long-term bank loans Type of loans Period and payment term December 31, 2022 December 31, 2023 NT$000 NT$000 Government granted bank loans Borrowing period is from March 11, 2020 to October 15, 2032; interest is repayable monthly; principal is repayable monthly from March 15, 2023 14,056,131 14,972,311 Less: Unamortized interest on ( 88,330 ) ( 60,592 ) Less: Current portion (fee included) ( 1,522,917 ) ( 2,263,718 ) 12,444,884 12,648,001 Interest rate range 1.075 %~ 1.625 % 1.2 %~ 1.75 % Unused credit lines of long-term NT$000 9,671,868 7,232,770 a) On January 1, 2019, Ministry of Economic Affairs, ROC (“MOEA”) implemented the Action Plan for Welcoming Overseas Taiwanese Businesses to Return to Invest in Taiwan and companies are subsidized with preferential interest loans for qualified investment projects. The Company has obtained the qualification from the MOEA, and signed loan agreements with financial institutions during January 2020 and September 2022 with the line of credit amounted to NT$ 23.73 billion and terms from seven to ten y ears . Funding from these loans was used to invest in machineries, equipment and plant expansions and broaden the Company’s working capital. b) On May 15, 2018, the Company entered into a syndicated loan with eleven banks in Taiwan, including Taiwan Cooperative Bank, in the amount of NT$ 12 billion with a term of five years . Funding from this syndicated loan was used to repay the existing debt of financial institutions and broaden the Company’s mid-term working capital. Pursuant to the syndicated loan agreement, the Group is required to maintain certain financial ratios including current ratio, interest protection multiples and debt to equity ratio during the loan periods. The syndicated loan was fully repaid in advance in March 2022. c) Information about the items that are pledged to others as collaterals for long-term bank loans is provided in Note 36.

Pensions

Pensions	12 Months Ended
	Dec. 31, 2023
Disclosure of defined benefit plans [abstract]
Pensions	18. Pensions a) Defined Benefit Plans The Company has a defined benefit pension plan in accordance with the Labor Standards Act, covering all regular employees’ service years prior to the enforcement of the Labor Pension Act on July 1, 2005 and service years thereafter of employees who chose to continue to be subject to the pension mechanism under the Labor Standards Act. Under the defined benefit pension plan, two units are accrued for each year of service for the first 15 years and one unit for each additional year thereafter , subject to a maximum of 45 units. Pension benefits are based on the number of units accrued and the average monthly salaries and wages of the last 6 months prior to retirement. The Company contributes monthly an amount equal to 2 % of the employees’ monthly salaries and wages to the pension fund deposited with the Bank of Taiwan, the trustee, under the name of the independent pension fund committee. Also, the Company would assess the balance in the aforementioned labor pension reserve account by the end of every year. If the account balance is insufficient to pay the pension calculated by the aforementioned method, to the employees expected to be qualified for retirement next year, the Company will make contributions to cover the deficit by March of following year. (a) The amounts recognized in the statements of financial position are as follows: December 31, 2022 December 31, 2023 NT$000 NT$000 Present value of defined benefit obligations ( 759,548 ) ( 744,191 ) Fair value of plan assets 500,333 516,854 Net defined benefit liability ( 259,215 ) ( 227,337 ) (b) Movements in net defined benefit liability are as follows: 2021 Present value of Fair value of Net defined NT$000 NT$000 NT$000 January 1 ( 943,391 ) 431,740 ( 511,651 ) Current services cost ( 237 ) — ( 237 ) Interest (expense) income ( 4,629 ) 2,137 ( 2,492 ) ( 948,257 ) 433,877 ( 514,380 ) Remeasurements: Return on plan assets (excluding amounts included — 5,613 5,613 Impact on changes in demographic assumptions ( 20,022 ) — ( 20,022 ) Financial assumption movement effect 23,757 — 23,757 Experience adjustments ( 24,347 ) — ( 24,347 ) ( 20,612 ) 5,613 ( 14,999 ) Pension fund contribution — 26,091 26,091 Paid pension 9,192 ( 9,192 ) — December 31 ( 959,677 ) 456,389 ( 503,288 ) 2022 Present value of Fair value of Net defined NT$000 NT$000 NT$000 January 1 ( 959,677 ) 456,389 ( 503,288 ) Current services cost ( 257 ) — ( 257 ) Interest (expense) income ( 6,589 ) 3,161 ( 3,428 ) ( 966,523 ) 459,550 ( 506,973 ) Remeasurements: Return on plan assets (excluding amounts included — 34,550 34,550 Financial assumption movement effect 73,218 — 73,218 Experience adjustments 114,466 — 114,466 187,684 34,550 222,234 Pension fund contribution — 25,524 25,524 Paid pension 19,291 ( 19,291 ) — December 31 ( 759,548 ) 500,333 ( 259,215 ) 2023 Present value of Fair value of Net defined NT$000 NT$000 NT$000 January 1 ( 759,548 ) 500,333 ( 259,215 ) Current services cost ( 133 ) — ( 133 ) Interest (expense) income ( 11,150 ) 7,441 ( 3,709 ) ( 770,831 ) 507,774 ( 263,057 ) Remeasurements: Return on plan assets (excluding amounts included — 3,187 3,187 Impact on changes in demographic assumptions 14,216 — 14,216 Financial assumption movement effect ( 7,103 ) — ( 7,103 ) Experience adjustments 399 — 399 7,512 3,187 10,699 Pension fund contribution — 25,021 25,021 Paid pension 19,128 ( 19,128 ) — December 31 ( 744,191 ) 516,854 ( 227,337 ) (c) The Bank of Taiwan was commissioned to manage the fund of the Company’s defined benefit pension plan in accordance with the fund’s annual investment and utilization plan and the Regulations for Revenues, Expenditures, Safeguard and Utilization of the Labor Retirement Fund (Article 6: The scope of utilization for the fund includes deposit in domestic or foreign financial institutions, investment in domestic or foreign listed, over-the-counter, or private placement equity securities, investment in domestic or foreign real estate securitization products, etc.). With regard to the utilization of the fund, its minimum earnings in the annual distributions on the final financial statements shall be no less than the earnings attainable from the amounts accrued from two-year time deposits with the interest rates offered by local banks. If the earnings are less than aforementioned rates, government shall make payment for the deficit after being authorized by the authority. The Company has no right to participate in managing and operating that fund and hence the Company is unable to disclose the classification of the fair value of plan asset in accordance with IAS 19, “Employee Benefits” paragraph 142. The composition of fair value of plan assets as of December 31, 2022 and 2023 is given in the Annual Labor Retirement Fund Utilization Report announced by the government. (d) The principal actuarial assumptions used were as follows: Year ended December 31, 2022 2023 Discount rate 1.50 % 1.40 % Future salary increase 3.50 % 3.50 % Assumptions regarding future mortality are set based on actuarial advice in accordance with published statistics and experience in each territory. The present value of defined benefit obligations is affected by the change in actuarial assumption. The analysis was as follows: Discount rate Future salary increase Increase 0.25 % Decrease 0.25 % Increase 0.25 % Decrease 0.25 % NT$000 NT$000 NT$000 NT$000 December 31, 2022 Effect on present value of defined benefit obligations ( 20,992 ) 21,860 21,385 ( 20,651 ) December 31, 2023 Effect on present value of defined benefit obligations ( 17,562 ) 18,228 17,817 ( 17,262 ) The sensitivity analysis above is based on a change in an assumption while holding all other assumptions constant. In practice, changes in some of the assumptions may be correlated. The method of sensitivity analysis and the method of calculating net defined benefit liability in the statements of financial position are the same. The methods and types of assumptions used in preparing the sensitivity analysis remain unchanged from previous period. (e) Expected contributions to the defined benefit pension plans of the Company for the year ending December 31, 2024 amounts to NT$ 24,000 thousand. (f) As of December 31, 2023, the weighted average duration of that retirement plan is 9.7 years. The analysis of timing of the future pension payment was as follows: December 31, 2023 NT$000 Within 1 year 69,288 1-2 years 42,487 2-5 years 115,279 5-10 years 181,850 408,904 b) Defined Contribution Plans (a) Effective from July 1, 2005, the Company established a defined contribution pension plan (“New Plan”) under the Labor Pension Act, covering all regular employees with ROC nationality. Under the New Plan, the Company contributes monthly an amount based on 6 % of the employees’ monthly salaries and wages to the employees’ individual pension accounts at the Bureau of Labor Insurance. The benefits accrued are paid monthly or in lump sum upon termination of employment. The pension costs under defined contribution pension plans of the Company for the years ended December 31, 2021, 2022 and 2023 were NT$ 197,076 thousand, NT$ 201,606 thousand and NT$ 190,913 thousand, respectively. (b) According to the defined contribution pension plan stipulated by PRC, ChipMOS Shanghai contributes monthly on amount based on a certain percentage of the local employees’ monthly salaries and wages. The contribution percentage was both 16 % for the years ended December 31, 2021, 2022 and 2023. The pension of each employee is managed by the government and ChipMOS Shanghai has no further obligations except the monthly contribution. The pension costs under defined contribution pension plan of ChipMOS Shanghai for the years ended December 31, 2021, 2022 and 2023 were NT$ 209 thousand, NT$ 380 thousand and NT$ 604 thousand, respectively.

Capital stock

Capital stock	12 Months Ended
	Dec. 31, 2023
Issued capital [abstract]
Capital stock	19. Capital stock a) As of December 31, 2023 , the Company’s authorized capital was NT$ 9,700,000 thousand, consisting of 970,000 thousand ordinary shares, and the paid-in capital was NT$ 7,272,401 thousand with a par value of NT$ 10 per share, consisting of 727,240 thousand ordinary shares. All proceeds from shares issued have been collected. b) As of December 31, 2023, the outstanding ADSs were approximately 4,234,970 units representing 84,699 thousand ordinary shares and each ADS represents 20 ordinary shares of the Company. The major terms and conditions of the ADSs are summarized as follows: (a) Voting rights: ADS holders have no right to directly attend, vote or speak in shareholders’ meetings with respect to the deposited shares. The depository bank shall vote on behalf of ADS holders or provide voting instruction to the designated person of the Company. The depository bank shall vote in the manner as instructed by ADS holders. (b) Distribution of dividends: ADS holders are deemed to have the same rights as holders of ordinary shares with respect to the distribution of dividends. c) The number of the Company’s ordinary shares outstanding as of January 1 and December 31 of 2021, 2022 and 2023 were all 727,240 thousand shares, respectively.

Capital surplus

Capital surplus	12 Months Ended
	Dec. 31, 2023
Capital surplus [Abstract]
Capital surplus	20. Capital surplus Pursuant to the ROC Company Act, any capital surplus arising from paid-in capital in excess of par value on issuance of ordinary shares and donations can be used to cover accumulated deficits or to issue new shares or cash to shareholders in proportion to their share ownership, provided that the Company has no accumulated deficits. Furthermore, the ROC Securities and Exchange Act requires that the amount of capital surplus to be capitalized mentioned above may not exceed 10% of the paid-in capital each year. The capital surplus may not be used to cover accumulated deficits unless the surplus reserve is insufficient. 2021 Share Others Total NT$000 NT$000 NT$000 January 1 6,043,483 7,304 6,050,787 Changes in associates accounted for using equity method — 4,834 4,834 December 31 6,043,483 12,138 6,055,621 2022 Share Others Total NT$000 NT$000 NT$000 January 1 6,043,483 12,138 6,055,621 Changes in associates accounted for using equity method — 152 152 December 31 6,043,483 12,290 6,055,773 2023 Share Others Total NT$000 NT$000 NT$000 January 1 6,043,483 12,290 6,055,773 December 31 6,043,483 12,290 6,055,773

Retained earnings

Retained earnings	12 Months Ended
	Dec. 31, 2023
Retained earnings [abstract]
Retained earnings	21. Retained earnings a) Under the Company’s Articles of Incorporation, upon the final settlement of accounts, if there is net profit, the Company shall first set aside the tax payable and offset its losses before setting aside a legal capital reserve at 10% of the remaining profit. The Company shall then set aside or reverse the special capital reserve in accordance with the laws and regulations and as requested by the competent authorities. The remaining profit of that fiscal year, as well as the accumulated undistributed profit at the beginning of the same year and the adjusted undistributed profit of the given fiscal year, shall be distributable profit. If there is any surplus distributable profit after the Board of Directors sets aside a reserve based on the Company’s operational needs, such surplus profit may be distributed in full or in part to shareholders as dividends, subject to the approval of the shareholders’ meeting. b) The Company’s dividend policy is summarized here. A proposal on the distribution of dividends shall be submitted by the Board of Directors annually to the shareholders’ meeting, and be based on factors such as past years’ profit, the current and future investment environment, the Company’s capital needs, competition in the domestic and foreign markets, and budgets, with an aim to pursuing shareholders’ interests and balancing the dividend distribution and the long-term financial plan of the Company. The distribution of profits of the Company can be made in the form of cash dividends or stock dividends, provided that the cash dividend shall account for at least 10% of the total profit distributed as dividends in the given year. c) Except for covering accumulated deficits or issuing new shares or cash to shareholders in proportion to their share ownership, the legal reserve may not be used for any other purpose. The use of the legal reserve for the issuance of shares or cash to shareholders in proportion to their share ownership is permitted, provided that the distribution of the reserve is limited to the portion in excess of 25% of the Company’s paid-in capital. d) In accordance with the regulations, the Company must set aside a special reserve from the debit balance on other equity items at the statements of financial position date before distributing earnings. When the debit balance on other equity items is reversed subsequently, the reversed amount may be included in the distributable earnings. e) The appropriations of 2020, 2021 and 2022 earnings were resolved in the shareholders’ meeting held on July 12, 2021, May 26, 2022 and May 30, 2023, respectively. The appropriations and dividends per share are as follows: 2020 2021 2022 Amount Cash Amount Cash Amount Cash NT$000 NT$ NT$000 NT$ NT$000 NT$ Legal reserve 232,611 505,482 354,986 Special reserve ( 19,802 ) — — Cash dividend 1,599,928 2.20 3,127,133 4.30 1,672,652 2.30

Other equity interest

Other equity interest	12 Months Ended
	Dec. 31, 2022
Disclosure of reserves within equity [abstract]
Other equity interest	22. Other equity interest 2021 Financial statements Unrealized gain (loss) Total NT$000 NT$000 NT$000 January 1 ( 61,330 ) 194,716 133,386 Currency translation differences - The Company ( 24,695 ) — ( 24,695 ) Evaluation adjustment - The Company — 122,514 122,514 - Associates — 21,094 21,094 Evaluation adjustment related tax - The Company — ( 30,459 ) ( 30,459 ) December 31 ( 86,025 ) 307,865 221,840 2022 Financial statements Unrealized gain (loss) Total NT$000 NT$000 NT$000 January 1 ( 86,025 ) 307,865 221,840 Currency translation differences - The Company 68,656 — 68,656 Evaluation adjustment - The Company — ( 46,419 ) ( 46,419 ) - Associates — ( 28,353 ) ( 28,353 ) Evaluation adjustment related tax - The Company — 12,559 12,559 December 31 ( 17,369 ) 245,652 228,283 2023 Financial statements Unrealized gain (loss) on valuation of Equity directly related to non-current assets held for sale Total NT$000 NT$000 NT$000 NT$000 January 1 ( 17,369 ) 245,652 — 228,283 Currency translation differences - The Company 16,713 — — 16,713 - Non-current assets held for sale — — ( 43,094 ) ( 43,094 ) Evaluation adjustment - The Company — ( 217,785 ) — ( 217,785 ) - Associates — 12,605 — 12,605 Evaluation adjustment related tax - The Company — 51,638 — 51,638 December 31 ( 656 ) 92,110 ( 43,094 ) 48,360

Revenue

Revenue	12 Months Ended
	Dec. 31, 2023
Receivables from contracts with customers [abstract]
Revenue	23. Revenue Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Revenue from contracts with customers 27,400,035 23,517,064 21,356,228 a) The Group is primarily engaged in the assembly and testing services of high-integration and high-precision integrated circuits, and recognized revenue based on the progress towards completion of performance obligation during the service period. Information on revenue disaggregation is provided in Note 42. b) Contract assets The Group has recognized the following contract assets in relation to revenue from contracts with customers: January 1, 2022 December 31, 2022 December 31, 2023 NT$000 NT$000 NT$000 Contract assets 400,255 381,358 383,883 c) The information relating to loss allowance for contract assets is provided in Note 41 a). d) All of the service contracts are for periods of one year or less. As permitted under IFRS 15, “Revenue from Contracts with Customers”, the transaction price allocated to these unsatisfied contracts is not disclosed.

Other income (expenses), net

Other income (expenses), net	12 Months Ended
	Dec. 31, 2023
Other income expenses net [abstract]
Other income (expenses), net	24. Other income (expenses), net Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Gain on disposal of property, plant and equipment, net 33,935 74,548 18,431 Gain on disposal of scrapped materials 52,254 35,381 44,662 Gain on disposal of items purchased on behalf of others 21,945 19,107 12,729 Gain from lease modifications 891 139 — Impairment loss on property, plant and equipment ( 4,843 ) ( 12,721 ) ( 9,236 ) Others 21,405 13,479 19,357 125,587 129,933 85,943

Interest income

Interest income	12 Months Ended
	Dec. 31, 2023
Disclosure of Interest Income [Abstract]
Interest income	25. Interest income Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Bank deposits 8,772 56,612 191,265 Financial assets at amortized cost 1,187 587 1,861 Other interest income 21 — 63 9,980 57,199 193,189

Other income

Other income	12 Months Ended
	Dec. 31, 2023
Other Income [Abstract]
Other income	26. Other income Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Rental income 17,326 35,848 48,264 Grant income 12,480 21,327 22,727 Dividend income 4,690 9,816 6,592 34,496 66,991 77,583

Other gains and losses

Other gains and losses	12 Months Ended
	Dec. 31, 2023
Disclosure of Other gains and losses [Abstract]
Other gains and losses	27. Other gains and losses Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Foreign exchange (losses) gains, net ( 89,152 ) 448,097 78,170 Gain (loss) on valuation of financial assets at fair value 15,262 ( 69,404 ) 39,254 Reimbursement of ADSs service charge 2,284 2,412 2,121 Compensation income 1,524 174 20 Others 4,253 5,288 15,936 ( 65,829 ) 386,567 135,501

Finance costs

Finance costs	12 Months Ended
	Dec. 31, 2023
Finance costs [Abstract]
Finance costs	28. Finance costs Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Interest expense Bank loans 116,946 138,731 254,892 Lease liabilities 15,245 14,556 18,757 Others — 8 — Less: Amounts capitalized in qualifying assets ( 11,193 ) ( 10,856 ) ( 7,692 ) 120,998 142,439 265,957 Finance expense 10,186 10,840 433 131,184 153,279 266,390

Expenses by nature

Expenses by nature	12 Months Ended
	Dec. 31, 2023
Analysis of income and expense [abstract]
Expenses by nature	29. Expenses by nature Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Raw materials and supplies used 5,518,145 4,512,527 3,991,490 Employee benefit expenses 6,757,888 6,466,303 5,836,068 Depreciation expenses 4,634,112 4,751,902 4,779,333 Others 5,053,088 4,699,586 4,926,828 21,963,233 20,430,318 19,533,719

Employee benefit expenses

Employee benefit expenses	12 Months Ended
	Dec. 31, 2023
Employee benefit expenses [Abstract]
Employee benefit expenses	30. Employee benefit expenses Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Salaries 5,632,219 5,302,234 4,741,380 Directors’ remuneration 40,164 28,621 23,980 Labor and health insurance 424,901 449,223 432,568 Pension 200,014 205,671 195,359 Other personnel expenses 460,590 480,554 442,781 6,757,888 6,466,303 5,836,068 a) In accordance with the Company’s Articles of Incorporation, employees’ compensation is based on the current year’s earnings, which should first be used to cover accumulated deficits, if any, and then 10 % of the remaining balance distributed as employees’ compensation, including distributions to certain qualifying employees in affiliate companies, and no more than 0.5 % as directors’ remuneration. Subject to the Board of Directors’ approval, employees’ compensation may be made by way of cash or share issuance. Distribution of employees’ compensation and directors’ remuneration shall be presented and reported in the subsequent shareholders’ meeting. b) Based on profit as of the end of reporting period, for the years ended December 31, 2021, 2022 and 2023 , the employees’ compensation were accrued at NT$ 673,387 thousand, NT$ 447,303 thousand and 250,181 thousand, respectively; the directors’ remuneration were accrued at NT$ 25,690 thousand, NT$ 11,182 thousand and NT$ 6,255 thousand, respectively. c) For the year of 2022 , employees’ compensation and directors’ remuneration recognized were consistent with the amounts resolved in the Board of Directors’ meeting.

Income tax expense

Income tax expense	12 Months Ended
	Dec. 31, 2023
Income tax expense [abstract]
Income tax expense	31. Income tax expense a) Income tax expense (a) Components of income tax expense: Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Current income tax: Current income tax on profits for the period 1,109,752 771,378 426,878 Income tax on unappropriated retained earnings 227,467 159,744 85,607 Prior year income tax overestimation ( 184,284 ) ( 255,935 ) ( 182,778 ) Total current income tax 1,152,935 675,187 329,707 Deferred income tax: Relating to origination and reversal of temporary differences ( 54,617 ) ( 87,012 ) ( 29,046 ) Income tax expense 1,098,318 588,175 300,661 (b) The income tax (charge)/credit relating to components of other comprehensive income are as follows: Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Unrealized gain (loss) on valuation of financial assets at 30,459 ( 12,559 ) ( 51,638 ) Remeasurement of defined benefit obligations ( 2,999 ) 44,447 2,140 27,460 31,888 ( 49,498 ) b) Reconciliation of income tax expense and the accounting profit: Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Tax calculated based on profit before tax and statutory tax rate 1,207,605 804,086 451,676 Effects from adjustments based on regulation ( 152,618 ) ( 131,873 ) ( 74,094 ) Gain on investment in associates — 11,923 19,228 Prior year income tax overestimation ( 184,284 ) ( 255,935 ) ( 182,778 ) Income tax on unappropriated retained earnings 227,467 159,744 85,607 Effect of different tax rates in countries in which the Group operates 148 230 1,022 Income tax expense 1,098,318 588,175 300,661 c) The amounts of deferred tax assets or liabilities resulting from temporary differences and investment tax credits are as follows: 2021 January 1 Recognized in Recognized December 31 NT$000 NT$000 NT$000 NT$000 Deferred tax assets Loss on inventories 15,963 8,354 — 24,317 Property, plant and equipment 36,401 235 — 36,636 Provisions 2,678 171 — 2,849 Deferred revenue 21,144 ( 6,506 ) — 14,638 Net defined benefit liability 98,921 ( 4,672 ) 2,999 97,248 Unrealized exchange losses 9,915 ( 7,754 ) — 2,161 Others 669 2,080 — 2,749 Total 185,691 ( 8,092 ) 2,999 180,598 Deferred tax liabilities Property, plant and equipment ( 255,484 ) 62,797 — ( 192,687 ) Financial assets at fair value through other ( 54,943 ) — ( 30,459 ) ( 85,402 ) Others — ( 88 ) — ( 88 ) Total ( 310,427 ) 62,709 ( 30,459 ) ( 278,177 ) Information presented on statements of Deferred tax assets 185,691 180,598 Deferred tax liabilities ( 310,427 ) ( 278,177 ) 2022 January 1 Recognized in Recognized December 31 NT$000 NT$000 NT$000 NT$000 Deferred tax assets Loss on inventories 24,317 ( 3,191 ) — 21,126 Property, plant and equipment 36,636 2,258 — 38,894 Provisions 2,849 10,010 — 12,859 Deferred revenue 14,638 ( 6,506 ) — 8,132 Net defined benefit liability 97,248 ( 4,368 ) ( 44,447 ) 48,433 Unrealized exchange losses 2,161 22,056 — 24,217 Others 2,749 2,876 — 5,625 Total 180,598 23,135 ( 44,447 ) 159,286 Deferred tax liabilities Property, plant and equipment ( 192,687 ) 75,713 — ( 116,974 ) Financial assets at fair value through other ( 85,402 ) — 12,559 ( 72,843 ) Gain on investment in associates — ( 11,923 ) — ( 11,923 ) Others ( 88 ) 87 — ( 1 ) Total ( 278,177 ) 63,877 12,559 ( 201,741 ) Information presented on statements of Deferred tax assets 180,598 159,286 Deferred tax liabilities ( 278,177 ) ( 201,741 ) 2023 January 1 Recognized in Recognized December 31 NT$000 NT$000 NT$000 NT$000 Deferred tax assets Loss on inventories 21,126 16,127 — 37,253 Property, plant and equipment 38,894 1,847 — 40,741 Provisions 12,859 1,518 — 14,377 Deferred revenue 8,132 ( 6,506 ) — 1,626 Net defined benefit liability 48,433 ( 4,236 ) ( 2,140 ) 42,057 Unrealized exchange losses 24,217 ( 6,032 ) — 18,185 Others 5,625 3,418 — 9,043 Total 159,286 6,136 ( 2,140 ) 163,282 Deferred tax liabilities Property, plant and equipment ( 116,974 ) 42,142 — ( 74,832 ) Financial assets at fair value through other ( 72,843 ) — 51,638 ( 21,205 ) Gain on investment in associates ( 11,923 ) ( 19,228 ) — ( 31,151 ) Others ( 1 ) ( 4 ) — ( 5 ) Total ( 201,741 ) 22,910 51,638 ( 127,193 ) Information presented on statements of Deferred tax assets 159,286 163,282 Deferred tax liabilities ( 201,741 ) ( 127,193 ) d) The Company has not recognized taxable temporary differences associated with investments as deferred tax liabilities. As of December 31, 2022 and 2023, the amounts of temporary differences not recognized as deferred tax liabilities were NT$ 1,080,272 thousand and NT$ 1,245,171 thousand, respectively. The Company’s income tax returns through 2021 have been assessed and approved by the Tax Authority.

Earnings per share

Earnings per share	12 Months Ended
	Dec. 31, 2023
Earnings per share [abstract]
Earnings per share	32. Earnings per share Year ended December 31, 2021 Amount after income tax Weighted average Earnings Basic earnings per share NT$000 In thousands NT$ Profit attributable to equity holders of the Company 4,937,267 727,240 6.79 Diluted earnings per share Assumed conversion of all dilutive potential ordinary shares: Employees’ compensation 15,618 Profit attributable to equity holders of the Company 4,937,267 742,858 6.65 Year ended December 31, 2022 Amount after income tax Weighted average Earnings Basic earnings per share NT$000 In thousands NT$ Profit attributable to equity holders of the Company 3,439,697 727,240 4.73 Diluted earnings per share Assumed conversion of all dilutive potential ordinary shares: Employees’ compensation 15,406 Profit attributable to equity holders of the Company 3,439,697 742,646 4.63 Year ended December 31, 2023 Amount after income tax Weighted average Earnings Basic earnings per share NT$000 In thousands NT$ Profit attributable to equity holders of the Company 1,967,565 727,240 2.71 Diluted earnings per share Assumed conversion of all dilutive potential ordinary shares: Employees’ compensation 7,698 Profit attributable to equity holders of the Company 1,967,565 734,938 2.68

Supplemental cash flow informat

Supplemental cash flow information	12 Months Ended
	Dec. 31, 2023
Statement of cash flows [abstract]
Supplemental cash flow information	33. Supplemental cash flow information Partial cash paid for investing activities Property, plant and equipment Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Purchase of property, plant and equipment 6,552,702 4,918,482 3,228,471 Add: Beginning balance of payable to equipment suppliers 1,145,359 1,816,555 1,405,931 Less: Ending balance of payable to equipment suppliers ( 1,816,555 ) ( 1,405,931 ) ( 1,196,181 ) Less: Ending balance of payable to equipment suppliers — — ( 58,549 ) Less: Transfer from other non-current assets — ( 629,737 ) ( 305,791 ) Cash paid during the year 5,881,506 4,699,369 3,073,881

Changes in liabilities from fin

Changes in liabilities from financing activities	12 Months Ended
	Dec. 31, 2023
Disclosure of reconciliation of liabilities arising from financing activities [abstract]
Changes in liabilities from financing activities	34. Changes in liabilities from financing activities 2021 Short-term Long-term bank Guarantee Lease Total liabilities NT$000 NT$000 NT$000 NT$000 NT$000 January 1 — 7,733,565 21,670 870,495 8,625,730 Changes in cash flow from financing 731,751 1,652,332 ( 45 ) ( 289,668 ) 2,094,370 Adjustment of right-of-use assets — — — 255,179 255,179 Amortization of loan fees — 7,646 — — 7,646 Amortization of interest expense — 19,822 — 15,245 35,067 December 31 731,751 9,413,365 21,625 851,251 11,017,992 2022 Short-term Long-term bank Guarantee Lease Total liabilities NT$000 NT$000 NT$000 NT$000 NT$000 January 1 731,751 9,413,365 21,625 851,251 11,017,992 Changes in cash flow from financing ( 731,751 ) 4,513,672 ( 25 ) ( 237,869 ) 3,544,027 Adjustment of right-of-use assets — — — 292,464 292,464 Amortization of loan fees — 10,026 — — 10,026 Amortization of interest expense — 30,738 — 14,556 45,294 December 31 — 13,967,801 21,600 920,402 14,909,803 2023 Long-term bank Guarantee Lease Total liabilities NT$000 NT$000 NT$000 NT$000 January 1 13,967,801 21,600 920,402 14,909,803 Changes in cash flow from financing 907,306 ( 365 ) ( 293,383 ) 613,558 Adjustment of right-of-use assets — — 419,625 419,625 Amortization of interest expense 36,612 — 18,757 55,369 December 31 14,911,719 21,235 1,065,401 15,998,355

Related party transactions

Related party transactions	12 Months Ended
	Dec. 31, 2023
Related party transactions [abstract]
Related party transactions	35. Related party transactions a) Parent and ultimate controlling party The Company has neither a parent company nor an ultimate controlling party. The transactions between the Company and its subsidiaries were eliminated in the accompanying consolidated financial statements and were not disclosed herein. The transactions between the Group and other related parties are as follows. b) Names of related parties and relationship Name Relationship Unimos Shanghai Associate JMC Associate Daypower Energy Associate Siliconware Precision Industries Co., Ltd. (“SPIL”) Entity that has significant influence over the Company c) Significant related party transactions (a) Payable to equipment suppliers December 31, 2022 December 31, 2023 NT$000 NT$000 Daypower Energy — 58,549 (b) Acquisition of property, plant and equipment Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 SPIL — — 35,261 d) Key management personnel compensation Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Salaries and other short-term employee benefits 243,405 211,620 176,702 Post-employment compensation 2,156 2,197 2,158 245,561 213,817 178,860

Pledged assets

Pledged assets	12 Months Ended
	Dec. 31, 2023
Disclosure assets pledged as collateral [abstract]
Pledged assets	36. Pledged assets Carrying amount Assets Purpose December 31, 2022 December 31, 2023 NT$000 NT$000 Non-current financial assets at amortized cost Lease and bank loan 37,362 37,411 Property, plant and equipment, net - Land Bank loan 452,738 454,738 - Buildings Bank loan 5,385,508 5,299,221 - Machinery and equipment Bank loan 8,204,983 8,173,618 14,080,591 13,964,988

Significant contingent liabilit

Significant contingent liabilities and unrecognized contract commitments	12 Months Ended
	Dec. 31, 2023
Capital commitments [abstract]
Significant contingent liabilities and unrecognized contract commitments	37. Significant contingent liabilities and unrecognized contract commitments a) A letter of guarantee was issued by the financial institutions to the Customs Administration of the Ministry of Finance for making payment of customs-duty deposits when importing. As of December 31, 2022 and 2023 , the amounts guaranteed by the financial institutions were NT$ 135,600 thousand and NT$ 71,900 thou sand, respectively. b) Capital expenditures that are contracted for, but not provided for are as follows: December 31, 2022 December 31, 2023 NT$000 NT$000 Property, plant and equipment, net 1,703,841 1,940,740

Significant disaster loss

Significant disaster loss	12 Months Ended
	Dec. 31, 2023
Disclosure of significant disaster loss [abstract]
Significant disaster loss	38. Significant disaster loss None.

Significant events after the re

Significant events after the reporting periods	12 Months Ended
	Dec. 31, 2023
Significant events after the reporting period [Abstract]
Significant events after the reporting periods	39. Significant events after the reporting period On December 21, 2023, the Company’ s Board of Directors approved its subsidiary ChipMOS BVI to sell the 45.0242 % owned equity investment accounted for using equity method in Unimos Shanghai. The equity transfer is expected to be completed in the first half of 2024.

Capital management

Capital management	12 Months Ended
	Dec. 31, 2023
Disclosure of objectives, policies and processes for managing capital [abstract]
Capital management	40. Capital management The Group’s objectives when managing capital are to safeguard the Group’s ability to continue as a going concern in order to provide returns for shareholders and to maintain an optimal capital structure to reduce the cost of capital. In order to maintain or adjust the capital structure, the Group may adjust the amount of dividends paid to shareholders, return capital to shareholders, issue new shares or sell assets to reduce debt. The Group monitors capital on the basis of the liabilities to assets ratio. Total capital is shown as “Equity” in the consolidated statements of financial position, which is also equal to total assets minus total liabilities. The liabilities to assets ratio at December 31, 2022 and 2023 were as follows: December 31, 2022 December 31, 2023 NT$000 NT$000 Total liabilities 20,303,685 21,397,287 Total assets 44,942,945 46,160,484 Liabilities to assets ratio 45.18 % 46.35 %

Financial risk management and f

Financial risk management and fair values of financial instruments	12 Months Ended
	Dec. 31, 2023
Disclosure of detailed information about financial instruments [abstract]
Financial risk management and fair values of financial instruments	41. Financial risk management and fair values of financial instruments a) Financial instruments (a) Financial instruments by category December 31, 2022 December 31, 2023 NT$000 NT$000 Financial assets Financial assets at fair value through profit or loss Financial assets mandatorily measured at fair value 128,224 42,735 Financial assets at fair value through other Designation of equity instruments 338,102 120,317 Financial assets at amortized cost Cash and cash equivalents 9,896,604 12,354,035 Financial assets at amortized cost 136,093 78,477 Accounts receivable 4,381,563 5,326,381 Other receivables 131,863 44,576 Refundable deposits 21,771 20,707 15,034,220 17,987,228 Financial liabilities Financial liabilities at amortized cost Notes payable 132 484 Accounts payable 560,802 784,919 Other payables 3,796,481 3,479,045 Other payables – related parties — 58,549 Long-term bank loans (including current portion) 13,967,801 14,911,719 Lease liabilities (including current portion) 920,402 1,065,401 Guarantee deposits 21,600 21,235 19,267,218 20,321,352 (b) Risk management policies i) The Group’s risk management objective is to manage the market risk, credit risk and liquidity risk related to its operating activities. The Group identifies, measures, and manages such risks by its policies and preferences. ii) The Group has established appropriate policies, procedures and internal controls for financial risk management. Before entering into significant financial transactions, a due approval process must be carried out by the Board of Directors based on related protocols and internal control procedures. The Group complies with its financial risk management policies at all times. iii) In order to minimize and manage financial risks, the Group’s overall risk management program focuses on analyzing, identifying, and evaluating financial risk factors that may potentially have adverse effects on the Group’s financial position, and provide feasible solutions to avoid those factors. (c) Significant financial risks and degrees of financial risks i) Market risk The Group’s market risk is the risk that the fair value or future cash flows of a financial instrument will fluctuate because of changes in market prices. Market risks comprise foreign currency risk, interest rate risk, and other price risks. In practice, the risk variable rarely changes individually, and the change of each risk variable is usually correlative. The following sensitivity analysis did not consider the interaction of each risk variable. Foreign exchange risk 1. The Group’s exposure to the risk of changes in foreign exchange rates relates primarily to the Group’s operating activities (when revenue or expense is denominated in a different currency from the Company’s and its subsidiaries’ functional currency) and the Group’s net investments in foreign operations. 2. The Group applies natural hedges by using accounts receivable and accounts payable denominated in the same currency. However, this natural hedge does not concur with the requirement for hedge accounting. Furthermore, as net investments in foreign operations are for strategic purposes, they are not hedged by the Group. 3. The Group’s foreign currency exposure gives rise to market risks associated with exchange rate movements against the NT dollar for cash and cash equivalents, accounts receivable, other receivables, bank loans, accounts payable and other payables (including related parties). 4. The Group’s businesses involve some non-functional currency operations. The information on assets and liabilities denominated in foreign currencies whose values would be materially affected by the exchange rate fluctuations is as follows: December 31, 2022 Foreign Exchange Carrying amount (Foreign currency: functional currency) Financial assets Monetary items US$000 208,989 30.7100 6,418,052 JPY000 114,940 0.2324 26,712 RMB000 7,199 4.4080 31,733 Non-monetary items JPY000 1,454,830 0.2324 338,102 RMB000 927,037 4.4080 4,086,378 Financial liabilities Monetary items US$000 11,031 30.7100 338,762 JPY000 1,587,732 0.2324 368,989 December 31, 2023 Foreign Exchange Carrying amount (Foreign currency: functional currency) Financial assets Monetary items US$000 149,837 30.7050 4,600,745 JPY000 188,904 0.2172 41,030 RMB000 5,595 4.3270 24,210 Non-monetary items JPY000 553,946 0.2172 120,317 Financial liabilities Monetary items US$000 21,175 30.7050 650,178 JPY000 1,102,264 0.2172 239,412 5. The total exchange (losses) gains, including realized and unrealized (losses) gains arising from significant foreign exchange variations on monetary items held by the Group for the years ended December 31, 2021, 2022 and 2023 , amounted to (NT$ 89,152 ) thousand, NT$ 448,097 thousand and NT$ 78,170 thousand , respectively. 6. Analysis of foreign currency market risk arising from significant foreign exchange variations: Year ended December 31, 2021 Sensitivity analysis Change in Effect on profit Effect on other Financial assets Monetary items US$000 5 % 260,390 — JPY000 5 % 1,702 — RMB000 5 % 1,074 — Financial liabilities Monetary items US$000 5 % 73,410 — JPY000 5 % 13,103 — Year ended December 31, 2022 Sensitivity analysis Change in Effect on profit Effect on other Financial assets Monetary items US$000 5 % 320,903 — JPY000 5 % 1,336 — RMB000 5 % 1,587 — Financial liabilities Monetary items US$000 5 % 16,938 — JPY000 5 % 18,449 — Year ended December 31, 2023 Sensitivity analysis Change in Effect on profit Effect on other Financial assets Monetary items US$000 5 % 230,037 — JPY000 5 % 2,052 — RMB000 5 % 1,211 — Financial liabilities Monetary items US$000 5 % 32,509 — JPY000 5 % 11,971 — Price risk 1. The Group’s financial instruments, which are exposed to price risk, are the financial assets at fair value through profit or loss and financial assets at fair value through other comprehensive income. To manage its price risk arising from investments in financial instruments, the Group diversifies its portfolio. Diversification of the portfolio is in accordance with the limits set by the Group. 2. The Group invests in beneficiary certificates and listed stocks issued by the domestic companies. The prices of equity securities would change due to change of the future value of investee companies. For the years ended December 31, 2021, 2022 and 2023 , it is estimated that the prices of equity securities increase or decrease by 1 %, with all other variables held constant, would increase or decrease the Group’s profit before income tax by NT$ 3,600 thousand, NT$ 1,282 thousand and NT$ 427 thousand , respectively. 3. The Group’s investments in financial instruments comprise foreign unlisted stocks. The prices of financial instruments would change due to different valuation models and assumptions used. Analysis related to the effect on profit or other comprehensive income if these assumptions change is provided in Note 41 b) (g). Interest rate risk on cash flow and fair value 1. Interest rate risk is the risk that the fair value or future cash flows of a financial instrument will fluctuate because of changes in market interest rates. The Group’s exposure to the risk of changes in market interest rates relates primarily to the Group’s bank loans with floating interest rates. The Group manages its interest rate risk by having a balanced portfolio of fixed and variable rate bank loans. The Group reassesses the hedge management periodically to make sure it complies with the cost effectiveness. 2. The sensitivity analysis depends on the exposure of interest rate risk at the end of the reporting period. 3. Analysis of debt with floating interest rates is based on the assumption that the outstanding debt at the end of the reporting period is outstanding throughout the period. The degree of variation the Group used to report to internal management is increase or decrease of 1% in interest rates which is assessed as the reasonable degree of variation by the management. 4. For the years ended December 31, 2021, 2022 and 2023 , it is estimated that a general increase or decrease of 1 % in interest rates, with all other variables held constant, would decrease or increase the Group’s profit before income tax approximately by NT$ 102,489 thousand, NT$ 140,561 thousand and NT$ 149,723 thousand, respectively, mainly due to the Group’s floating rate on bank loans. ii) Credit risk 1. Credit risk is the risk that a counterparty will not meet its obligations under a financial instrument or customer contract, leading to a financial loss, mainly resulted from its operating activities (primarily accounts receivable) and from its financing activities (primarily deposits with banks and financial instruments). The Group is exposed to credit risk arising from the carrying amount of the financial assets recognized in the consolidated statements of financial position. 2. Each business unit performs ongoing credit evaluations of its debtors’ financial conditions according to the Group’s established policies, procedures and controls relating to customer credit risk management. The Group maintains an account for loss allowance based upon the available facts and circumstances, history of collection and write-off experiences of all trade and other receivables which consequently minimize the Group’s exposure to bad debts. 3. Credit risk from balances with banks and financial institutions is managed by the Group’s finance unit in accordance with the Group’s policies. Transaction counterparty of the Group is determined through its internal controls policy. For banks and financial institutions, only parties rated above BBB+ by Taiwan Ratings are accepted. The probability of counterparty default is remote, so there is no significant credit risk. 4. The Group adopts the assumptions under IFRS 9, “Financial Instruments” and the default is deemed to have occurred when the contract payments are past due over 90 days. 5. The Group categorized contract assets, accounts receivable and other receivables by characteristics of credit risk and applied the simplified approach using loss rate methodology to estimate expected credit loss. 6. The Group referred to the forecastability of business monitoring indicators published by the ROC National Development Council to adjust the loss rate which is based on historical and current information when assessing the future default possibility of contract assets, accounts receivable and other receivables. As of December 31, 2022 and 2023 the loss rate methodologies are as follows: December 31, 2022 Contract Accounts receivable Other receivables NT$000 NT$000 NT$000 Expected loss rate 0.060 % 0.060 % 0.060 % Total carrying amount 381,587 4,384,232 131,908 Loss allowance ( 229 ) ( 2,669 ) ( 45 ) December 31, 2023 Contract Accounts receivable Other receivables NT$000 NT$000 NT$000 Expected loss rate 0.045 % 0.045 % 0.045 % Total carrying amount 384,057 5,328,835 44,589 Loss allowance ( 174 ) ( 2,454 ) ( 13 ) 7. Under the simplified approach, movements in relation to loss allowance for contract assets, accounts receivable, and other receivables are as follows: 2021 Contract Accounts receivable Other receivables NT$000 NT$000 NT$000 January 1 ( 117 ) ( 1,620 ) ( 10 ) Provision for impairment loss ( 3 ) ( 290 ) ( 6 ) December 31 ( 120 ) ( 1,910 ) ( 16 ) 2022 Contract Accounts receivable Other receivables NT$000 NT$000 NT$000 January 1 ( 120 ) ( 1,910 ) ( 16 ) Provision for impairment loss ( 109 ) ( 759 ) ( 29 ) December 31 ( 229 ) ( 2,669 ) ( 45 ) 2023 Contract Accounts receivable Other receivables NT$000 NT$000 NT$000 January 1 ( 229 ) ( 2,669 ) ( 45 ) Reversal of impairment loss 55 215 32 December 31 ( 174 ) ( 2,454 ) ( 13 ) 8. The Group’s recorded financial assets at amortized cost include time deposits with contract period over 3 months and restricted bank deposits. Because of the low credit risk, expected credit losses for the period are measured through a loss allowance at an amount equal to the 12-month expected credit losses. There is no significant provision for the losses. iii) Liquidity risk 1. The Group manages and maintains adequate cash and cash equivalents to finance the Group’s operations, and minimize the impact from cash flow fluctuations. The Group also monitors its debt financing plans to ensure it is in compliance with the financial covenants required under its loan agreements. 2. The primary source of liquidity for the Group is from bank loans. See Note 17 for details of the unused credit lines of the Group as of December 31, 2022 and 2023. 3. The contractual undiscounted cash flows of notes payable, accounts payable and other payables (including related parties) due within one year and is equivalent to its carrying amount. Except for the aforementioned, the table below summarizes the maturity profile of the Group’s non-derivative financial liabilities based on the earliest repayment dates and contractual undiscounted payments, including principal and interest. The Group does not consider the probability of early repayments requested by the banks. December 31, 2022 Within 1 to 3 years 3 to 5 years Over Total NT$000 NT$000 NT$000 NT$000 NT$000 Non-derivative financial liabilities Long-term bank loans 1,699,165 5,675,288 5,354,335 1,914,280 14,643,068 Lease liabilities 174,460 182,767 57,057 704,503 1,118,787 Guarantee deposits — — — 21,600 21,600 1,873,625 5,858,055 5,411,392 2,640,383 15,783,455 December 31, 2023 Within 1 to 3 years 3 to 5 years Over Total NT$000 NT$000 NT$000 NT$000 NT$000 Non-derivative financial liabilities Long-term bank loans 2,469,744 7,506,844 4,273,199 1,330,797 15,580,584 Lease liabilities 267,759 250,104 57,856 681,975 1,257,694 Guarantee deposits — — — 21,235 21,235 2,737,503 7,756,948 4,331,055 2,034,007 16,859,513 The difference between the floating interest rates and estimated interest rates will affect the non-derivative financial liabilities stated above. b) Fair value information (a) The different levels of inputs used in valuation techniques to measure fair value of financial and non-financial instruments are defined as follows: Level 1: Quoted prices (unadjusted) in active markets for identical assets or liabilities that can be accessed at the measurement date. An active market is a market in which trading for the asset or liability takes place with sufficient frequency and volume to provide pricing information on an ongoing basis. Level 2: Inputs other than quoted prices from Level 1 that are observable information for the asset or liability, either directly or indirectly. Level 3: Unobservable inputs for the asset or liability. The fair value of the Group’s investment in equity investment without active market is included in Level 3. (b) The carrying amounts of cash and cash equivalents, financial assets at amortized cost, contract assets, accounts receivable, other receivables, refundable deposits, long-term bank loans, notes payable, accounts payable, other payables (including related parties), and guarantee deposits are approximate to their fair values. (c) The related information of financial and non-financial instruments measured at fair value by level based on the nature, characteristics and risks of the assets and liabilities are as follows: i) The related information of natures of the assets and liabilities are as follows: December 31, 2022 Level 1 Level 2 Level 3 Total NT$000 NT$000 NT$000 NT$000 Assets Recurring fair value measurements Financial assets at fair value through profit or loss - Listed stocks 128,224 — — 128,224 Financial assets at fair value through other - Foreign unlisted stocks — — 338,102 338,102 128,224 — 338,102 466,326 December 31, 2023 Level 1 Level 2 Level 3 Total NT$000 NT$000 NT$000 NT$000 Assets Recurring fair value measurements Financial assets at fair value through profit or loss - Listed stocks 42,735 — — 42,735 Financial assets at fair value through other - Foreign unlisted stocks — — 120,317 120,317 42,735 — 120,317 163,052 ii) The methods and assumptions the Group used to measure fair value are as follows: 1. The fair value of the Group’s listed stocks is measured by using the market quoted prices, which is categorized within Level 1 fair value. 2. Except for listed stocks with active markets, the fair value of the Group’s other financial instruments is measured by using valuation techniques or by reference to counterparty quotes. The fair value of financial instruments measured by using valuation techniques can be referred to current fair value of instruments with similar terms and characteristics in substance, discounted cash flow method or other valuation methods, including calculated by applying model using market information available at the consolidated statement of financial position date. 3. The Group’s financial instruments issued by foreign companies are measured by the comparable company valuation (EV/EBITDA ratio and P/B ratio). 4. The Group takes into account adjustments for credit risks to measure the fair value of financial and non-financial instruments to reflect credit risk of the counterparty and the Group’s credit quality. (d) The following table shows the movements of Level 3 for the years ended December 31, 2022 and 2023: Equity instruments 2022 2023 NT$000 NT$000 January 1 384,521 338,102 Gains or losses recognized in other comprehensive income Recorded as unrealized loss on valuation of financial assets ( 46,419 ) ( 217,785 ) Purchases — 12,500 Reclassified as investments accounted for using equity method — ( 12,500 ) December 31 338,102 120,317 (e) The Group performs the fair value measurements being categorized within Level 3 with assistance from specialist. Such assessment is to ensure the valuation results are reasonable by applying independent information to make results close to current market conditions, confirming the resource of information is independent, reliable and in line with other resources and represented as the exercisable price, and frequently calibrating valuation model, updating inputs used to the valuation model and making any other necessary adjustments to the fair value. (f) The following is the qualitative information and sensitivity analysis of changes in significant unobservable inputs under valuation model used in Level 3 fair value measurement: Fair value as of Valuation Significant Range Relationship of inputs NT$000 Non-derivative equity Foreign unlisted stocks 338,102 Comparable companies Enterprise value to 4.82 The higher the multiple, the higher the fair value Discount for lack of 15.80 % The higher the discount for lack of marketability, the lower the fair value Fair value as of Valuation Significant Range Relationship of NT$000 Non-derivative equity Foreign unlisted stocks 120,317 Comparable companies Enterprise value to 8.23 The higher the multiple, the higher the fair value Price to book ratio multiple 1.64 The higher the multiple, the higher the fair value Discount for lack of 15.70 % The higher the discount for lack of marketability, the lower the fair value (g) The Group has carefully assessed the valuation models and assumptions used to measure fair value. However, use of different valuation models or assumptions may result in different measurement. The following is the effect of profit or loss or of other comprehensive income from financial assets categorized within Level 3 if the inputs used to valuation models have changed: December 31, 2022 Recognized in Recognized in other Input Change Favorable Unfavorable Favorable Unfavorable NT$000 NT$000 NT$000 NT$000 Financial assets: Foreign unlisted stocks Enterprise value to ±1% — — 2,876 2,883 Discount for lack ±1% — — 3,990 4,039 — — 6,866 6,922 December 31, 2023 Recognized in Recognized in other Input Change Favorable Unfavorable Favorable Unfavorable NT$000 NT$000 NT$000 NT$000 Financial assets: Foreign unlisted stocks Enterprise value to ±1% — — 748 709 Price to book ratio ±1% — — 30 30 Discount for lack ±1% — — 1,453 1,413 — — 2,231 2,152

Segment information

Segment information	12 Months Ended
	Dec. 31, 2023
Disclosure of operating segments [abstract]
Segment information	42. Segment information a) General information The Group engages mainly in the assembly and testing of semiconductors, memory modules and general investments. In accordance with IFRS 8, “Operating Segments”, the Group’s segments include Testing, Assembly, LCDD, Bumping and others as the five reportable segments. b) Measurement of segment information The Group’s reportable segments are strategic business units which provide different products and services. The accounting policies adopted by the operating segments are the same as the accounting policies described in Note 4. c) Information about segment profit or loss The segment information provided to the chief operating decision maker for the reportable segments is as follows: Year ended December 31, 2021 Testing Assembly LCDD Bumping Others Elimination Total NT$000 NT$000 NT$000 NT$000 NT$000 NT$000 NT$000 Revenue External customers 5,899,600 7,963,714 8,211,099 5,325,622 — — 27,400,035 Inter-segment — — — — 43,808 ( 43,808 ) — Total revenue 5,899,600 7,963,714 8,211,099 5,325,622 43,808 ( 43,808 ) 27,400,035 Operating profit (loss) 1,814,021 857,304 2,336,394 561,642 ( 6,987 ) 15 5,562,389 Depreciation expenses ( 921,999 ) ( 576,138 ) ( 2,579,150 ) ( 549,020 ) ( 7,805 ) — ( 4,634,112 ) Share of profit of — — — — 1,211,177 ( 585,444 ) 625,733 Interest income — — — — 9,980 — 9,980 Interest expense — — — — ( 120,998 ) — ( 120,998 ) Purchase of property, 1,841,359 1,553,475 2,748,697 408,751 420 — 6,552,702 Year ended December 31, 2022 Testing Assembly LCDD Bumping Others Elimination Total NT$000 NT$000 NT$000 NT$000 NT$000 NT$000 NT$000 Revenue External customers 5,243,997 6,705,898 7,288,642 4,278,527 — — 23,517,064 Inter-segment — — — — 50,600 ( 50,600 ) — Total revenue 5,243,997 6,705,898 7,288,642 4,278,527 50,600 ( 50,600 ) 23,517,064 Operating profit (loss) 1,253,477 ( 93,585 ) 1,795,741 268,159 ( 6,821 ) ( 292 ) 3,216,679 Depreciation expenses ( 1,042,455 ) ( 694,835 ) ( 2,505,297 ) ( 500,863 ) ( 8,452 ) — ( 4,751,902 ) Share of profit of — — — — 884,555 ( 430,840 ) 453,715 Interest income — — — — 57,199 — 57,199 Interest expense — — — — ( 142,439 ) — ( 142,439 ) Purchase of property, 1,086,682 957,790 2,677,489 196,521 — — 4,918,482 Year ended December 31, 2023 Testing Assembly LCDD Bumping Others Elimination Total NT$000 NT$000 NT$000 NT$000 NT$000 NT$000 NT$000 Revenue External customers 4,394,726 4,629,430 7,821,640 4,510,432 — — 21,356,228 Inter-segment — — — — 59,481 ( 59,481 ) — Total revenue 4,394,726 4,629,430 7,821,640 4,510,432 59,481 ( 59,481 ) 21,356,228 Operating profit (loss) 514,707 ( 1,180,481 ) 2,058,285 522,386 ( 6,194 ) ( 251 ) 1,908,452 Depreciation expenses ( 1,065,689 ) ( 722,462 ) ( 2,547,253 ) ( 435,709 ) ( 8,220 ) — ( 4,779,333 ) Share of profit of — — — — 420,393 ( 200,502 ) 219,891 Interest income — — — — 193,189 — 193,189 Interest expense — — — — ( 265,957 ) — ( 265,957 ) Purchase of property, 749,158 568,289 1,756,590 152,908 1,526 — 3,228,471 d) Reconciliation for segment income (loss) Revenue from external customers and segment income (loss) reported to the chief operating decision maker are measured using the same method as for revenue and operating profit in the financial statements. Thus, no reconciliation is needed. e) Information on products and services Year ended December 31, 2021 2022 2023 NT$000 % NT$000 % NT$000 % Testing 5,899,600 22 5,243,997 22 4,394,726 20 Assembly 7,963,714 29 6,705,898 29 4,629,430 22 LCDD 8,211,099 30 7,288,642 31 7,821,640 37 Bumping 5,325,622 19 4,278,527 18 4,510,432 21 27,400,035 100 23,517,064 100 21,356,228 100 f) Geographical information Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Revenue ROC 21,608,567 18,671,142 17,287,574 Japan 1,768,460 1,989,805 1,176,163 PRC 1,899,362 1,970,943 1,729,908 Singapore 1,630,733 390,488 676,088 Others 492,913 494,686 486,495 27,400,035 23,517,064 21,356,228 December 31, 2022 December 31, 2023 NT$000 NT$000 Non-current assets ROC 21,677,980 20,360,166 PRC 2,291 1,279 Others 576 6,122 21,680,847 20,367,567 g) Major customer information The information on the major customers which constituted more than 10% of the Group’s total revenue for the years ended December 31, 2021, 2022 and 2023 is as follows: Year ended December 31, 2021 2022 2023 NT$000 % NT$000 % NT$000 % Customers Customer A 5,681,277 21 4,705,064 20 5,251,529 25 Customer B 2,484,611 9 1,868,583 8 2,834,188 13 Customer M 2,832,088 10 2,278,645 10 1,320,905 6

Financial statements schedule_

Financial statements schedule: valuation and qualifying accounts	12 Months Ended
	Dec. 31, 2023
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Financial statements schedule: valuation and qualifying accounts	43. Financial statements schedule: valuation and qualifying accounts January 1 Additions charged Deduction / December 31 NT$000 NT$000 NT$000 NT$000 Year 2021 Allowance for impairment of property, plant 182,002 4,843 ( 3,666 ) 183,179 Allowance for impairment of obsolescence 79,815 41,771 — 121,586 Provision for deficiency compensation 3,463 11,898 ( 11,080 ) 4,281 Sales for allowance 9,864 34,744 ( 34,759 ) 9,849 Year 2022 Allowance for impairment of property, plant 183,179 12,721 ( 1,433 ) 194,467 Allowance for impairment of obsolescence 121,586 — ( 15,956 ) 105,630 Provision for deficiency compensation 4,281 79,827 ( 57,465 ) 26,643 Sales for allowance 9,849 94,641 ( 67,367 ) 37,123 Year 2023 Allowance for impairment of property, plant 194,467 9,236 — 203,703 Allowance for impairment of obsolescence 105,630 80,633 — 186,263 Provision for deficiency compensation 26,643 21,495 ( 14,574 ) 33,564 Sales for allowance 37,123 112,488 ( 111,944 ) 37,667 For movements in loss allowance for contract assets, accounts receivable, and other receivables, please refer to Note 41 a).

Summary of material accountin_2

Summary of material accounting policies (Policies)	12 Months Ended
	Dec. 31, 2023
Summary Of Material Accounting Policies [Abstract]
Statement of compliance	a) Statement of compliance The consolidated financial statements of the Group have been prepared in accordance with IFRSs as issued by the IASB.
Basis of preparation	b) Basis of preparation (a) Except for the following items, the consolidated financial statements have been prepared under the historical cost convention: i) Financial assets at fair value through profit or loss (including derivative instruments). ii) Financial assets at fair value through other comprehensive income. iii) Defined benefit liabilities were recognized based on the net amount of pension fund assets less the present value of benefit obligation. (b) The preparation of the consolidated financial statements in conformity with IFRSs requires the use of certain critical accounting estimates. It also requires management to exercise its judgment in the process of applying the Group’s accounting policies. The areas involving a higher degree of judgment or complexity, or areas where assumptions and estimates are significant to the consolidated financial statements are disclosed in Note 4 dd). (c) These consolidated financial statements are presented in New Taiwan dollars (“NT$”), which is the Company’s functional currency.
Basis of consolidation	c) Basis of consolidation (a) Basis for preparation of consolidated financial statements: i) All subsidiaries are included in the Group’s consolidated financial statements. Subsidiaries are all entities controlled by the Group. The Group controls an entity when the Group is exposed, or has rights, to variable returns from its involvement with the entity and has the ability to affect those returns through its power over the entity. Consolidation of subsidiaries begins from the date the Group obtains control of the subsidiaries and ceases when the Group loses control of the subsidiaries. ii) Transactions, balances and unrealized gains or losses on transactions between companies within the Group are eliminated. Accounting policies of subsidiaries have been adjusted where necessary to ensure consistency with the policies adopted by the Group. iii) Profit or loss and each component of other comprehensive income are attributed to the owners of the parent and to the non-controlling interests. Total comprehensive income is attributed to the owners of the parent and to the non-controlling interests even if this results in a deficit balance in the non-controlling interests. iv) Changes in a parent’s ownership interest in a subsidiary that do not result in the parent losing control of the subsidiary (transactions with non-controlling interests) are accounted for as equity transactions, i.e. transactions with owners in their capacity as owners. Any difference between the amount by which the non-controlling interests are adjusted and the fair value of the consideration paid or received is recognized directly in equity. v) When the Group loses control of a subsidiary, the Group remeasures any investment retained in the former subsidiary at its fair value. That fair value is regarded as the fair value on initial recognition of a financial asset or the cost on initial recognition of the associate or joint venture. Any difference between fair value and carrying amount is recognized in profit or loss. All amounts previously recognized in other comprehensive income in relation to the subsidiary are reclassified to profit or loss on the same basis as would be required if the related assets or liabilities were disposed of. That is, when the Group loses control of a subsidiary, all gains or losses previously recognized in other comprehensive income in relation to the subsidiary should be reclassified from equity to profit or loss, if such gains or losses would be reclassified to profit or loss when the related assets or liabilities are disposed of. (b) Subsidiaries included in the consolidated financial statements: Percentage of December 31, Name of investor Name of investee Main business Location 2022 2023 The Company ChipMOS U.S.A., Inc. (“ChipMOS USA”) Marketing of semiconductors and electronic related products San Jose, USA 100 100 The Company ChipMOS TECHNOLOGIES (BVI) LTD. (“ChipMOS BVI”) Holding company British Virgin Islands 100 100 ChipMOS BVI ChipMOS SEMICONDUCTORS (Shanghai) LTD. (“ChipMOS Shanghai”) Marketing of semiconductors and electronic related products Shanghai, People’s Republic of China (“PRC”) 100 100 (c) Subsidiaries not included in the consolidated financial statements: None. (d) Adjustments for subsidiaries with different statements of financial position dates: Not applicable. (e) No significant restrictions on the ability of subsidiaries to transfer funds to parent company. (f) Subsidiaries that have non-controlling interests that are material to the Group: None.
Foreign currency translation	d) Foreign currency translation Items included in the financial statements of each of the Group’s entities are measured using the currency of the primary economic environment in which the entity operates (the “functional currency”). The consolidated financial statements are presented in NT$, which is the Company’s functional currency and the Group’s presentation currency. (a) Foreign currency transactions and balances i) Foreign currency transactions are translated into the functional currency using the exchange rates on the trade date or measurement date. Therefore, foreign exchange differences resulting from the settlement of such transactions are recognized in profit or loss in the period in which they arise. ii) Monetary assets and liabilities denominated in foreign currencies at the period end are re-translated at the exchange rates prevailing at the statements of financial position date. Exchange differences arising upon re-translation are recognized in profit or loss on the statements of financial position date. iii) Non-monetary assets and liabilities denominated in foreign currencies held at fair value through profit or loss are re-translated at the exchange rates prevailing at the statements of financial position date; their exchange differences are recognized in profit or loss. Non-monetary assets and liabilities denominated in foreign currencies held at fair value through other comprehensive income are re-translated at the exchange rates prevailing at the statements of financial position date; their exchange differences are recognized in other comprehensive income. However, non-monetary assets and liabilities denominated in foreign currencies that are not measured at fair value are translated using the historical exchange rates at the initial dates of the transactions. iv) All foreign exchange differences are presented in the statement of comprehensive income under “Other gains and losses” by the nature of transactions. (b) Translation of foreign operations The operating results and financial position of all the group entities, associates that have different functional currency and presentation currency are translated into the presentation currency as follows: i) Assets and liabilities for each statements of financial position are translated at the exchange rates prevailing at the statements of financial position date; ii) Income and expenses for each statement of comprehensive income are translated at average exchange rates of that period; and All exchange differences are recognized in other comprehensive income.
Classification of current and non-current assets and liabilities	e) Classification of current and non-current assets and liabilities (a) Assets that meet one of the following criteria are classified as current assets: i) Assets arising from operating activities that are expected to be realized, or are intended to be sold or consumed within the normal operating cycle; ii) Assets held mainly for trading purposes; iii) Assets that are expected to be realized within 12 months from the statements of financial position date; iv) Cash and cash equivalents, excluding restricted cash and cash equivalents and those that are to be exchanged or used to pay off liabilities more than 12 months after the statements of financial position date. All assets that do not meet the above criteria are classified as non-current assets. (b) Liabilities that meet one of the following criteria are classified as current liabilities: i) Liabilities that are expected to be settled within the normal operating cycle; ii) Liabilities arising mainly from trading activities; iii) Liabilities that are to be settled within 12 months from the statements of financial position date; iv) Liabilities for which the repayment date cannot be unconditionally extended to more than 12 months after the statements of financial position date. Liabilities bearing terms that could, at the option of the counterparty, result in its settlement by the issue of equity instruments do not affect its classification. All liabilities that do not meet the above criteria are classified as non-current liabilities.
Cash equivalents	f) Cash equivalents Cash equivalents refer to short-term, highly liquid investments that are readily convertible to known amounts of cash and are subject to an insignificant risk of changes in value (including time deposits with less than 3 months contract period). Time deposits that meet the above definition and are held for the purpose of meeting short-term cash commitments in operations are classified as cash equivalents.
Financial assets at fair value through profit or loss	g) Financial assets at fair value through profit or loss (a) Financial assets at fair value through profit or loss are financial assets that are not measured at amortized cost or fair value through other comprehensive income. (b) On a regular way purchase or sale basis, financial assets at fair value through profit or loss are recognized and derecognized using settlement date accounting. (c) At initial recognition, the Group measures the financial assets at fair value and recognizes the transaction costs in profit or loss. The Group subsequently measures the financial assets at fair value, and recognizes the gain or loss in profit or loss. (d) The Group recognizes the dividend income when the right to receive such payment is confirmed, inflow of the future economic benefits associated with the dividend is probable to the Group and the amount of the dividend can be measured reliably.
Financial assets at fair value through other comprehensive income	h) Financial assets at fair value through other comprehensive income (a) Financial assets at fair value through other comprehensive income comprise equity instruments which are not held for trading, and for which the Group has made an irrevocable election at initial recognition to recognize changes in fair value in other comprehensive income. (b) On a regular way purchase or sale basis, financial assets at fair value through other comprehensive income are recognized and derecognized using settlement date accounting. (c) At initial recognition, the Group measures the financial assets at fair value plus transaction costs. The Group subsequently measures the financial assets at fair value: The changes in fair value of equity instruments that were recognized in other comprehensive income are reclassified to retained earnings and are not reclassified to profit or loss following the derecognition of the investment. Dividends are recognized as income when the right to receive such payment is confirmed, inflow of the future economic benefits associated with the dividend is probable to the Group and the amount of the dividend can be measured reliably.
Financial assets at amortized cost	i) Financial assets at amortized cost (a) Financial assets at amortized cost are those that meet all of the following criteria: i) The objective of the Group’s business model is achieved by collecting contractual cash flows. ii) The financial assets’ contractual cash flows represent solely payments of principal and interest. (b) The Group’s time deposits which do not fall under cash equivalents are those with a short maturity period and are measured at initial investment amount as the effect of discounting is immaterial.
Accounts receivable	j) Accounts receivable (a) Accounts receivable entitle the Group a legal right to receive consideration in exchange for transferred goods or rendered services. The short-term accounts receivable without bearing interest are subsequently measured at initial invoice amount as the effect of discounting is immaterial.
Impairment of financial assets	k) Impairment of financial assets For financial assets at amortized cost, at each reporting date, the Group recognizes the impairment provision for 12 months expected credit losses if there has not been a significant increase in credit risk since initial recognition or recognizes the impairment provision for the lifetime expected credit losses if such credit risk has increased since initial recognition after taking into consideration all reasonable and verifiable information that includes forecasts. On the other hand, for accounts receivable or contract assets that do not contain a significant financing component, the Group recognizes the impairment provision for lifetime expected credit losses.
Derecognition of financial assets	l) Derecognition of financial assets The Group derecognizes a financial asset when the contractual rights to receive the cash flows from the financial asset have expired.
Inventories	m) Inventories Inventories are initially recorded at standard costs. Cost is determined on a weighted-average cost basis. At the end of reporting period, the differences between actual costs and standard costs were allocated to inventories and cost of revenue based on an appropriate rate. Allocation of fixed production overheads is based on the normal operating capacity of the production facilities. Costs associated with underutilized capacity are expensed in the period that the cost occurs. Inventories are valued at the lower of cost and net realizable value. Net realizable value is the estimated selling price in the ordinary course of business less the estimated costs of completion and the estimated costs necessary to make the sale. The item by item approach is used in raw materials. The amount of any write-down of inventories to net realizable value and all losses of inventories are recognized as an expense in the period the write-down or loss occurs.
Non-current assets held for sale	n) Non-current assets held for sale Non-current assets are classified as assets held for sale when their carrying amount is to be recovered principally through a sale transaction rather than through continuing use, and a sale is considered highly probable. They are stated at the lower of carrying amount and fair value less costs to sell.
Investments accounted for using equity method – associates	o) Investments accounted for using equity method – associates (a) Associates are all entities over which the Group has significant influence but not control. In general, it is presumed that the investor has significant influence, if an investor holds, directly or indirectly 20 percent or more of the voting power of the investee. Investments in associates are accounted for using the equity method and are initially recognized at cost. (b) The Group’s share of its associates’ post-acquisition profits or losses is recognized in profit or loss, and its share of post-acquisition movements in other comprehensive income is recognized in other comprehensive income. When the Group’s share of losses in an associate equals or exceeds its interests in the associate, including any other unsecured receivables, the Group does not recognize further losses, unless it has incurred legal or constructive obligations or made payments on behalf of the associate. (c) When changes in an associate’s equity that are not recognized in profit or loss or other comprehensive income of the associate and such changes not affecting the Group’s ownership percentage of the associate, the Group recognizes the Group’s share of change in equity of the associate in “Capital surplus” in proportion to its ownership. (d) Unrealized gains on transactions between the Group and its associates are eliminated to the extent of the Group’s interests in the associates. Unrealized losses are also eliminated unless the transaction provides evidence of an impairment of the asset transferred. Accounting policies of associates have been adjusted where necessary to ensure consistency with the policies adopted by the Group. (e) In the case where an associate issues new shares and the Group does not subscribe or proportionately acquire the new shares, which results in a change in the Group’s ownership percentage of the associate while maintaining significant influence on the associate, then the Group will treat the transaction as deemed disposal and reclassify to profit or loss the proportion of the gain or loss previously recognized in other comprehensive income relating to that reduction in ownership interest where appropriate. (f) When the Group disposes of its investment in an associate, if it loses significant influence on this associate, the amounts previously recognized in other comprehensive income in relation to the associate are reclassified to profit or loss, on the same basis as would be required if the relevant assets or liabilities were disposed of. If it still retains significant influence on this associate, then the amounts previously recognized in other comprehensive income in relation to the associate are reclassified to profit or loss proportionately in accordance with the aforementioned approach.
Property, plant and equipment	p) Property, plant and equipment (a) Property, plant and equipment are initially recorded at cost. Borrowing costs incurred during the construction period are capitalized. (b) Subsequent costs are included in the asset’s carrying amount or recognized as a separate asset, as appropriate, only when it is probable that future economic benefits associated with the item will flow to the Group and the cost of the item can be measured reliably. The carrying amount of the replaced part is derecognized. All other repairs and maintenance are charged to profit or loss during the financial period in which they are incurred. (c) Land is not depreciated. Other property, plant and equipment apply cost model and are depreciated using the straight-line method to allocate their cost over their estimated useful lives. Each part of an item of property, plant and equipment with a cost that is significant in relation to the total cost of the item must be depreciated separately. (d) The assets’ residual values, useful lives and depreciation methods are reviewed, and adjusted if appropriate, at each financial year-end. If expectations for the assets’ residual values and useful lives differ from previous estimates or the patterns of consumption of the assets’ future economic benefits embodied in the assets have changed significantly, any change is accounted for as a change in estimate under IAS 8, “Accounting Policies, Change in Accounting Estimates and Errors”, from the date of the change. The estimated u seful lives of property, plant and equipment are as follows: Buildings 1 to 51 years Machinery and equipment 1 to 20 years Tools 1 to 4 years Others 1 to 7 years
Leasing arrangements (lessee) – right-of-use assets / lease liabilities	q) Leasing arrangements (lessee) – right-of-use assets / lease liabilities (a) Leases are recognized as a right-of-use asset and a corresponding lease liability at the date at which the leased asset is available for use by the Group. For short-term leases or leases of low value assets, lease payments are recognized as an expense on a straight-line basis over the lease term. (b) Lease liabilities include the net present value of the remaining lease payments at the commencement date, discounted using the incremental borrowing interest rate. Lease payments are comprised of the following: i) Fixed payments, less any lease incentives receivable; ii) The exercise price of a purchase option, if the lessee is reasonably certain to exercise that option. The Group subsequently measures the lease liability at amortized cost using the interest method and recognizes interest expense over the lease term. The lease liability is remeasured and the amount of remeasurement is recognized as an adjustment to the right-of-use asset when there are changes in the lease term or lease payments and such changes do not arise from contract modifications. At the commencement date, the right-of-use asset is stated at the amount of the initial measurement of lease liability. The right-of-use asset is measured subsequently using the cost model and is depreciated from the commencement date to the earlier of the end of the asset’s useful life or the end of the lease term. When the lease liability is remeasured, the amount of remeasurement is recognized as an adjustment to the right-of-use asset.
Impairment of non-financial assets	r) Impairment of non-financial assets The Group assesses at each statements of financial position date the recoverable amounts of those assets where there is an indication that they are impaired. An impairment loss is recognized for the amount by which the asset’s carrying amount exceeds its recoverable amount. The recoverable amount is the higher of an asset’s fair value less costs to sell or value in use. When the circumstances or reasons for recognizing impairment loss for an asset in prior years no longer exist or diminish, the impairment loss is reversed. The increased carrying amount due to reversal should not be more than what the depreciated or amortized historical cost would have been if the impairment had not been recognized.
Loans	s) Loans Loans comprise long-term and short-term bank loans. Loans are recognized initially at fair value, net of transaction costs incurred. Loans are subsequently stated at amortized cost; any difference between the proceeds (net of transaction costs) and the redemption value is recognized as interest expense in profit or loss over the period of the loans using the effective interest method.
Accounts and notes payable	t) Accounts and notes payable (a) Accounts payable are liabilities for purchases of raw materials, goods or services and notes payable are those resulting from operating and non-operating activities. (b) The short-term accounts and notes payable without bearing interest are subsequently measured at initial invoice amount as the effect of discounting is immaterial.
Derecognition of financial liabilities	u) Derecognition of financial liabilities A financial liability is derecognized when the obligation specified in the contract is either discharged or cancelled or expires.
Provisions for deficiency compensation	v) Provisions for deficiency compensation Provisions are recognized when the Group has a present legal or constructive obligation as a result of past events, and it is probable that an outflow of economic resources will be required to settle the obligation and the amount of the obligation can be reliably estimated. Provisions are measured at the present value of the expenditures expected to be required to settle the obligation on the statements of financial position date, which is discounted using a pre-tax discount rate that reflects the current market assessments of the time value of money and the risks specific to the obligation. When discounting is used, the increase in the provision arising from the passage of time is recognized as interest expense. Provisions are not recognized for future operating losses
Employee benefits	w) Employee benefits (a) Short-term employee benefits Short-term employee benefits are measured at the undiscounted amount of the benefits expected to be paid in respect of service rendered by employees and should be recognized as expenses when the employees render service. (b) Pensions i) Defined contribution plans For defined contribution plans, the contributions are recognized as pension expenses when they are due on an accrual basis. Prepaid contributions are recognized as an asset to the extent of a cash refund or a reduction in future payments. ii) Defined benefit plans 1. Net obligation under a defined benefit plan is defined as the present value of an amount of pension benefits that employees will receive on retirement for their services with the Group in the current period or prior periods. The liability recognized in the statements of financial position in respect of defined benefit pension plans is the present value of the defined benefit obligation at the statements of financial position date less the fair value of plan assets. The net defined benefit obligation is calculated annually by independent actuaries using the projected unit credit method. The discount rate is determined by using the interest rates of government bonds that are denominated in the currency in which the benefits will be paid, and that have terms to maturity approximating to the terms of the related pension liability. 2. Remeasurements arising on defined benefit plans are recognized in other comprehensive income in the period in which they arise and are recorded as retained earnings. 3. Past service costs are recognized immediately in profit or loss. (c) Termination benefits Termination benefits are employee benefits provided in exchange for the termination of employment as a result from either the Group’s decision to terminate an employee’s employment before the normal retirement date, or an employee’s decision to accept an offer of redundancy benefits in exchange for the termination of employment. The Group recognizes an expense as it can no longer withdraw an offer of termination benefits, or it recognizes related restructuring costs, whichever is earlier. Benefits that are expected to be due more than 12 months after statements of financial position date shall be discounted to their present value. (d) Employees’ compensation and directors’ remuneration Employees’ compensation and directors’ remuneration are recognized as expenses and liabilities, provided that such recognition is required under legal obligation or constructive obligation and those amounts can be reliably estimated. Any difference between the resolved amounts and the subsequently actual distributed amounts is accounted for as changes in estimates. If employee compensation is paid by shares, the Company calculates the number of shares based on the closing price at the previous day of the board meeting resolution.
Income tax	x) Income tax (a) The income tax expense for the period comprises current and deferred tax. Income tax is recognized in profit or loss, except to the extent that it relates to items recognized in other comprehensive income or items recognized directly in equity, in which cases the income tax is recognized in other comprehensive income or equity. (b) The current income tax expense is calculated on the basis of the tax laws enacted or substantively enacted at the statements of financial position date in the countries where the Group and its subsidiaries operate and generate taxable income. Management periodically evaluates positions taken in tax returns with respect to situations in accordance with applicable tax regulations. It establishes provisions where appropriate based on the amounts expected to be paid to the tax authorities. An additional income tax is levied on the unappropriated retained earnings and is recorded as income tax expense in the year the profit generated. (c) Deferred tax is recognized, using the balance sheet liability method, on temporary differences arising between the tax bases of assets and liabilities and their carrying amounts in the consolidated statements of financial position. However, the deferred tax is not accounted for if it arises from initial recognition of an asset or liability in a transaction other than a business combination that at the time of the transaction affects neither accounting nor taxable profit or loss. Deferred tax is provided on temporary differences arising on investments in subsidiaries and associates, except where the timing of the reversal of the temporary difference is controlled by the Group and it is probable that the temporary difference will not reverse in the foreseeable future. Deferred tax is determined using tax rates (and laws) that have been enacted or substantially enacted at the statements of financial position date and are expected to apply when the related deferred tax asset is realized or the deferred tax liability is settled. (d) Deferred tax assets are recognized only to the extent that it is probable that future taxable profit will be available against which the temporary differences can be utilized. At each statements of financial position date, unrecognized and recognized deferred tax assets are reassessed. (e) A deferred tax asset shall be recognized for the carryforward of unused tax credits resulting from equity investments to the extent that it is possible that future taxable profit will be available against which the unused tax credits can be utilized. If a change in tax rate is enacted or substantively enacted, the Group recognizes the effect of the change immediately in the period in which the change occurs. The effect of the change on items recognized outside profit or loss is recognized in other comprehensive income or equity while the effect of the change on items recognized in profit or loss is recognized in profit or loss.
Capital stock	y) Capital stock (a) Ordinary shares are classified as equity. Incremental costs directly attributable to the issue of new shares in net proceeds of tax are shown in equity as a deduction. Where the Company repurchases the Company’s shares that have been issued, the consideration paid, including any directly attributable incremental costs (net of income taxes) is deducted from equity attributable to the Company’s equity holders. Where such shares are subsequently reissued, the difference between their book value and any consideration received, net of any directly attributable incremental transaction costs and the related income tax effects, is included in equity attributable to the Company’s equity holders.
Dividends	z) Dividends Dividends are recorded in the Company’s financial statements in the period in which they are resolved by the Company’s shareholders. Cash dividends are recorded as liabilities; stock dividends are recorded as stock dividends to be distributed and are reclassified to ordinary shares on the effective date of new shares issuance.
Revenue recognition	aa) Revenue recognition (a) The Group is primarily engaged in the customized assembly and testing services of high-integration and high-precision integrated circuits based on customer’s specification demand to create or enhance the product. When providing assembly and testing services, the Group considers: i) Customer controls the provided raw materials and the Group receives the instruction from the customer on providing assembly and testing services and subsequent treatments. ii) The Group provides assembly and testing services to create or enhance an asset which is solely provided and controlled by the customer. The Group has no right to transfer the asset for another use. As the asset ownership belongs to the customer, who bears the significant risk and rewards and rights on the use of the asset, the Group recognizes assembly and testing service revenue based on the progress towards completion of performance obligation during the service period. (b) The progress towards completion on Assembly services, services for Display panel driver semiconductor assembly and testing (“LCDD”) and Bumping are measured by the actual input costs relative to estimate total expected input costs. The progress towards completion on testing services is measured by the actual incurred testing volume. The Group provides assembly and testing services based on customer’s specification, thus, the input costs incurred to assembly and testing volume completed in testing services are not linear over the duration of these services. Customer payment on assembly and testing services is based on predetermined payment schedule. A contract asset is recognized when the Group provides services in excess of customer’s payment.
Government grants	bb) Government grants Government grants are recognized at their fair value only when there is reasonable assurance that the Group will comply with any conditions attached to the grants will be received. Government grants are recognized in profit or loss on a systematic basis over the periods in which the Group recognizes expenses for the related costs for which the grants are intended to compensate. Government grants related to property, plant and equipment are recognized as non-current liabilities and are amortized to profit or loss over the estimated useful lives of the related assets using straight-line method.
Operating segments	cc) Operating segments Operating segments are reported in a manner consistent with the internal reporting provided to the chief operating decision maker. The Group’s chief operating decision maker, who is responsible for allocating resources and assessing performance of the operating segments, has been identified as the Chairman of the Board of Directors that makes strategic decisions.
Critical accounting judgments, estimates and key sources of assumption uncertainty	dd) Critical accounting judgments, estimates and key sources of assumption uncertainty The preparation of the accompanying consolidated financial statements requires management to make critical judgments in applying the Group’s accounting policies and make critical assumptions and estimates concerning future events. Assumptions and estimates may differ from the actual results and are continually evaluated and adjusted based on historical experience and other factors. Such assumptions and estimates have a significant risk of causing a material adjustment to the carrying amounts of assets and liabilities within the next financial year; and the related information is addressed below: Critical accounting estimates and assumptions – Revenue recognition The Group recognizes revenue from services for Assembly, LCDD and Bumping based on the progress towards completion of performance obligation during the service period. The Group estimates total expected input costs based on historical experience and measures the progress towards completion by the actual input costs relative to the total expected input costs.

Summary of material accountin_3

Summary of material accounting policies (Tables)	12 Months Ended
	Dec. 31, 2023
Summary Of Material Accounting Policies [Abstract]
Summary of Ownership Interests in Subsidiaries	Percentage of December 31, Name of investor Name of investee Main business Location 2022 2023 The Company ChipMOS U.S.A., Inc. (“ChipMOS USA”) Marketing of semiconductors and electronic related products San Jose, USA 100 100 The Company ChipMOS TECHNOLOGIES (BVI) LTD. (“ChipMOS BVI”) Holding company British Virgin Islands 100 100 ChipMOS BVI ChipMOS SEMICONDUCTORS (Shanghai) LTD. (“ChipMOS Shanghai”) Marketing of semiconductors and electronic related products Shanghai, People’s Republic of China (“PRC”) 100 100
Estimated Useful Life for Depreciation of Individual Assets	Buildings 1 to 51 years Machinery and equipment 1 to 20 years Tools 1 to 4 years Others 1 to 7 years

Cash and cash equivalents (Tabl

Cash and cash equivalents (Tables)	12 Months Ended
	Dec. 31, 2023
Cash and cash equivalents [abstract]
Summary of Cash and Cash Equivalents	December 31, 2022 December 31, 2023 NT$000 NT$000 Cash on hand and petty cash 450 450 Checking accounts and demand deposits 2,248,954 1,434,939 Time deposits 7,647,200 10,918,646 9,896,604 12,354,035 a) The Group transacts with a variety of financial institutions all with high credit quality to disperse credit risk, so it expects that the probability of counterparty default is remote. b) No cash and cash equivalents of the Group were pledged to others.

Financial assets at fair valu_2

Financial assets at fair value through profit or loss (Tables)	12 Months Ended
	Dec. 31, 2023
Financial assets at fair value through profit or loss [abstract]
Summary of Financial Assets at Fair Value Through Profit or Loss	December 31, 2022 December 31, 2023 NT$000 NT$000 Current: Financial assets mandatorily measured at fair value Listed stocks 171,988 53,747 Valuation adjustment ( 43,764 ) ( 11,012 ) 128,224 42,735
Summary of Amounts recognized in Profit or Loss in Relation to Financial Assets at Fair Value Through Profit or Loss	a) Amounts recognized in profit or loss in relation to the financial assets at fair value through profit or loss are listed below: Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Financial assets mandatorily measured at fair value Listed stocks 13,673 ( 75,211 ) 22,001 Beneficiary certificates* 2,530 5,807 17,253 Foreign partnership interests ( 941 ) — — 15,262 ( 69,404 ) 39,254 * Beneficiary certificates represent money market funds the Company held during the reporting period. As of December 31, 2021, 2022 and 2023, there were no beneficiary certificates classified as current financial assets at fair value through profit or loss (“FVTPL”). b) No financial assets at FVTPL were pledged to others. c) I nformation relating to price risk of financial assets at FVTPL is provided in Note 41 a).

Financial assets at amortized_2

Financial assets at amortized cost (Tables)	12 Months Ended
	Dec. 31, 2023
Financial assets at amortized cost [Abstract]
Summary of Financial Assets at Amortized Cost	December 31, 2022 December 31, 2023 NT$000 NT$000 Current: Time deposits 98,731 41,066 Non-current: Restricted bank deposits 37,362 37,411 a) Amounts recognized in profit or loss in relation to financial assets at amortized cost are listed below: Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Interest income 1,187 587 1,861

Accounts receivable (Tables)

Accounts receivable (Tables)	12 Months Ended
	Dec. 31, 2023
Accounts Receivable [Abstract]
Summary of Accounts and notes receivable	December 31, 2022 December 31, 2023 NT$000 NT$000 Accounts receivable 4,384,232 5,328,835 Less: Loss allowance ( 2,669 ) ( 2,454 ) 4,381,563 5,326,381
Aging of Accounts Receivable which are Past Due but not Impaired	December 31, 2022 December 31, 2023 NT$000 NT$000 Current 4,357,073 5,326,523 Within 1 month 27,159 2,089 1-2 months — 223 4,384,232 5,328,835

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2023
Inventories [abstract]
Summary of Inventories	December 31, 2022 Cost Allowance for Carrying amount NT$000 NT$000 NT$000 Raw materials 3,316,039 ( 105,630 ) 3,210,409 December 31, 2023 Cost Allowance for Carrying amount NT$000 NT$000 NT$000 Raw materials 2,754,911 ( 186,263 ) 2,568,648
Cost of Inventories Recognized as an Expense	Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Cost of revenue 20,103,735 18,611,515 17,723,687 Loss on abandonment 552 9,448 2,483 Allowance for (reversal of) inventory 41,770 ( 15,956 ) 80,633 20,146,057 18,605,007 17,806,803

Non-current financial assets _2

Non-current financial assets at fair value through other comprehensive income (Tables)	12 Months Ended
	Dec. 31, 2023
Non-current financial assets at fair value through other comprehensive income [abstract]
Summary of Non-current Financial Assets at Fair Value Through Other Comprehensive Income	December 31, 2022 December 31, 2023 NT$000 NT$000 Designation of equity instruments Foreign unlisted stocks 38,534 38,534 Valuation adjustment 299,568 81,783 338,102 120,317
Summary Amounts recognized in other comprehensive income in relation to the financial assets at fair value through other comprehensive income	Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Financial assets at fair value through other Foreign unlisted stocks 122,514 ( 46,419 ) ( 217,785 )

Investments accounted for usi_2

Investments accounted for using equity method (Tables)	12 Months Ended
	Dec. 31, 2023
Investments accounted for using equity method [abstract]
Details of Investment in Associates	Associates December 31, 2022 December 31, 2023 NT$000 NT$000 JMC ELECTRONICS CO., LTD. (“JMC”) 267,070 277,076 Unimos Microelectronics (Shanghai) Co., Ltd. 4,086,378 — Daypower Energy — 13,466 4,353,448 290,542 Note: On December 21, 2023, the Company's Board of Directors approved its subsidiary ChipMOS BVI to sell the investment accounted for using equity method in Unimos Shanghai and reclassified the investment as non-current assets held for sale. Information relating to non-current assets held for sale is provided in Note 14.
Summarized Financial Information for Investment in Material Associates	Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Profit for the year from continuing operations 625,733 453,715 1,714 Other comprehensive income (loss), net of income tax 28,843 ( 28,254 ) 12,993 Total comprehensive income 654,576 425,461 14,707

Property, plant and equipment_2

Property, plant and equipment, net (Tables)	12 Months Ended
	Dec. 31, 2023
Disclosure of detailed information about property, plant and equipment [abstract]
Summary of Property, Plant and Equipment, Net	2021 Land Buildings Machinery Tools Others Construction in Total NT$000 NT$000 NT$000 NT$000 NT$000 NT$000 NT$000 January 1 Cost 452,738 11,212,129 53,246,474 5,451,547 2,185,299 639,607 73,187,794 Accumulated depreciation — ( 7,119,843 ) ( 41,898,177 ) ( 4,499,186 ) ( 1,675,902 ) — ( 55,193,108 ) 452,738 4,092,286 11,348,297 952,361 509,397 639,607 17,994,686 January 1 452,738 4,092,286 11,348,297 952,361 509,397 639,607 17,994,686 Additions — 1,345 11,829 407 189 6,538,932 6,552,702 Disposals — — ( 66,873 ) ( 9,502 ) — — ( 76,375 ) Reclassifications — 673,208 4,890,400 690,346 241,656 ( 6,495,610 ) — Depreciation expenses — ( 423,283 ) ( 2,896,612 ) ( 795,622 ) ( 239,515 ) — ( 4,355,032 ) Impairment losses — — ( 4,843 ) — — — ( 4,843 ) Exchange adjustment — — ( 13 ) — ( 4 ) — ( 17 ) December 31 452,738 4,343,556 13,282,185 837,990 511,723 682,929 20,111,121 December 31 Cost 452,738 11,877,419 57,176,339 5,574,316 2,345,204 682,929 78,108,945 Accumulated depreciation — ( 7,533,863 ) ( 43,894,154 ) ( 4,736,326 ) ( 1,833,481 ) — ( 57,997,824 ) 452,738 4,343,556 13,282,185 837,990 511,723 682,929 20,111,121 2022 Land Buildings Machinery Tools Others Construction in Total NT$000 NT$000 NT$000 NT$000 NT$000 NT$000 NT$000 January 1 Cost 452,738 11,877,419 57,176,339 5,574,316 2,345,204 682,929 78,108,945 Accumulated depreciation — ( 7,533,863 ) ( 43,894,154 ) ( 4,736,326 ) ( 1,833,481 ) — ( 57,997,824 ) 452,738 4,343,556 13,282,185 837,990 511,723 682,929 20,111,121 January 1 452,738 4,343,556 13,282,185 837,990 511,723 682,929 20,111,121 Additions — 3,780 6,748 636 — 4,907,318 4,918,482 Disposals — — ( 46,084 ) ( 2,597 ) — — ( 48,681 ) Reclassifications — 1,503,432 2,603,381 685,481 294,765 ( 5,086,047 ) 1,012 Depreciation expenses — ( 465,260 ) ( 3,075,191 ) ( 724,813 ) ( 257,817 ) — ( 4,523,081 ) Impairment losses — — ( 12,721 ) — — — ( 12,721 ) Exchange adjustment — — 50 — 23 — 73 December 31 452,738 5,385,508 12,758,368 796,697 548,694 504,200 20,446,205 December 31 Cost 452,738 13,379,852 59,197,255 5,716,357 2,615,959 504,200 81,866,361 Accumulated depreciation — ( 7,994,344 ) ( 46,438,887 ) ( 4,919,660 ) ( 2,067,265 ) — ( 61,420,156 ) 452,738 5,385,508 12,758,368 796,697 548,694 504,200 20,446,205 2023 Land Buildings Machinery Tools Others Construction in Total NT$000 NT$000 NT$000 NT$000 NT$000 NT$000 NT$000 January 1 Cost 452,738 13,379,852 59,197,255 5,716,357 2,615,959 504,200 81,866,361 Accumulated depreciation — ( 7,994,344 ) ( 46,438,887 ) ( 4,919,660 ) ( 2,067,265 ) — ( 61,420,156 ) 452,738 5,385,508 12,758,368 796,697 548,694 504,200 20,446,205 January 1 452,738 5,385,508 12,758,368 796,697 548,694 504,200 20,446,205 Additions — 1,303 5,579 291 1,376 3,219,922 3,228,471 Disposals — — ( 16,574 ) ( 11,038 ) — — ( 27,612 ) Reclassifications 2,000 469,597 1,787,140 586,090 226,610 ( 3,071,437 ) — Depreciation expenses — ( 557,187 ) ( 3,043,504 ) ( 635,227 ) ( 262,388 ) — ( 4,498,306 ) Impairment losses — — ( 9,236 ) — — — ( 9,236 ) Exchange adjustment — — — — ( 19 ) — ( 19 ) December 31 454,738 5,299,221 11,481,773 736,813 514,273 652,685 19,139,503 December 31 Cost 454,738 13,850,418 60,650,428 5,959,251 2,774,055 652,685 84,341,575 Accumulated depreciation — ( 8,551,197 ) ( 49,168,655 ) ( 5,222,438 ) ( 2,259,782 ) — ( 65,202,072 ) 454,738 5,299,221 11,481,773 736,813 514,273 652,685 19,139,503
Capitalization Interest and Capitalization Interest Rate Applied Related to Property, Plant and Equipment	Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Amount of interest capitalized 11,193 10,856 7,692 Range of the interest rates for capitalization 1.1358 % 1.0094 % 1.4588 %

Non-current assets held for s_2

Non-current assets held for sale (Tables)	12 Months Ended
	Dec. 31, 2023
Summary of Assets Held for Sale	a) Assets held for sale: December 31, 2023 NT$000 Investment accounted for using equity method in 4,278,658

Leasing arrangements - leasee (

Leasing arrangements - leasee (Tables)	12 Months Ended
	Dec. 31, 2023
Presentation of leases for lessee [abstract]
Summary of carrying amount of right-of-use assets and the depreciation expenses	b) The carrying amount of right-of-use assets and the depreciation expenses are as follows: Carrying amount December 31, 2022 December 31, 2023 NT$000 NT$000 Land 630,969 615,385 Buildings 8,214 7,723 Machinery and equipment 257,196 411,809 Others 2,613 2,585 898,992 1,037,502 Depreciation expenses Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Land 20,486 21,904 21,524 Buildings 9,870 10,861 11,738 Machinery and equipment 247,090 194,059 245,304 Others 1,634 1,997 2,461 279,080 228,821 281,027
Summary of profit and loss accounts relating to lease contracts	d) The information on profit or loss a ccounts relating to lease contracts is as follows: Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Items affecting profit or loss Interest expense on lease liabilities 15,245 14,556 18,757 Expense on short-term lease contracts 143,791 95,213 55,944

Other Payables (Tables)

Other Payables (Tables)	12 Months Ended
	Dec. 31, 2023
Trade and other current payables [abstract]
Summary of Other Payables	December 31, 2022 December 31, 2023 NT$000 NT$000 Payable to equipment suppliers 1,405,931 1,196,181 Salaries and bonuses payable 1,002,577 994,651 Employees’ compensation payable 447,303 250,181 Pension payable 16,541 16,825 Directors’ remuneration payable 11,182 6,255 Interest payable 7,768 9,625 Other expense payable 905,179 1,005,327 3,796,481 3,479,045

Long-term bank loans (Tables)

Long-term bank loans (Tables)	12 Months Ended
	Dec. 31, 2023
Borrowings [abstract]
Summary of Bank Loans	Type of loans Period and payment term December 31, 2022 December 31, 2023 NT$000 NT$000 Government granted bank loans Borrowing period is from March 11, 2020 to October 15, 2032; interest is repayable monthly; principal is repayable monthly from March 15, 2023 14,056,131 14,972,311 Less: Unamortized interest on ( 88,330 ) ( 60,592 ) Less: Current portion (fee included) ( 1,522,917 ) ( 2,263,718 ) 12,444,884 12,648,001 Interest rate range 1.075 %~ 1.625 % 1.2 %~ 1.75 % Unused credit lines of long-term NT$000 9,671,868 7,232,770

Pensions (Tables)

Pensions (Tables)	12 Months Ended
	Dec. 31, 2023
Disclosure of defined benefit plans [abstract]
Summary of Amounts Recognized in Statements of Financial Position	(a) The amounts recognized in the statements of financial position are as follows: December 31, 2022 December 31, 2023 NT$000 NT$000 Present value of defined benefit obligations ( 759,548 ) ( 744,191 ) Fair value of plan assets 500,333 516,854 Net defined benefit liability ( 259,215 ) ( 227,337 )
Summary of Movements in net Defined Benefit Liability	(b) Movements in net defined benefit liability are as follows: 2021 Present value of Fair value of Net defined NT$000 NT$000 NT$000 January 1 ( 943,391 ) 431,740 ( 511,651 ) Current services cost ( 237 ) — ( 237 ) Interest (expense) income ( 4,629 ) 2,137 ( 2,492 ) ( 948,257 ) 433,877 ( 514,380 ) Remeasurements: Return on plan assets (excluding amounts included — 5,613 5,613 Impact on changes in demographic assumptions ( 20,022 ) — ( 20,022 ) Financial assumption movement effect 23,757 — 23,757 Experience adjustments ( 24,347 ) — ( 24,347 ) ( 20,612 ) 5,613 ( 14,999 ) Pension fund contribution — 26,091 26,091 Paid pension 9,192 ( 9,192 ) — December 31 ( 959,677 ) 456,389 ( 503,288 ) 2022 Present value of Fair value of Net defined NT$000 NT$000 NT$000 January 1 ( 959,677 ) 456,389 ( 503,288 ) Current services cost ( 257 ) — ( 257 ) Interest (expense) income ( 6,589 ) 3,161 ( 3,428 ) ( 966,523 ) 459,550 ( 506,973 ) Remeasurements: Return on plan assets (excluding amounts included — 34,550 34,550 Financial assumption movement effect 73,218 — 73,218 Experience adjustments 114,466 — 114,466 187,684 34,550 222,234 Pension fund contribution — 25,524 25,524 Paid pension 19,291 ( 19,291 ) — December 31 ( 759,548 ) 500,333 ( 259,215 ) 2023 Present value of Fair value of Net defined NT$000 NT$000 NT$000 January 1 ( 759,548 ) 500,333 ( 259,215 ) Current services cost ( 133 ) — ( 133 ) Interest (expense) income ( 11,150 ) 7,441 ( 3,709 ) ( 770,831 ) 507,774 ( 263,057 ) Remeasurements: Return on plan assets (excluding amounts included — 3,187 3,187 Impact on changes in demographic assumptions 14,216 — 14,216 Financial assumption movement effect ( 7,103 ) — ( 7,103 ) Experience adjustments 399 — 399 7,512 3,187 10,699 Pension fund contribution — 25,021 25,021 Paid pension 19,128 ( 19,128 ) — December 31 ( 744,191 ) 516,854 ( 227,337 )
Principal Actuarial Assumptions	(d) The principal actuarial assumptions used were as follows: Year ended December 31, 2022 2023 Discount rate 1.50 % 1.40 % Future salary increase 3.50 % 3.50 %
Sensitivity Analysis of Present Value of Defined Benefit Obligations Effected by Changes of Significant Actuarial Assumptions	The present value of defined benefit obligations is affected by the change in actuarial assumption. The analysis was as follows: Discount rate Future salary increase Increase 0.25 % Decrease 0.25 % Increase 0.25 % Decrease 0.25 % NT$000 NT$000 NT$000 NT$000 December 31, 2022 Effect on present value of defined benefit obligations ( 20,992 ) 21,860 21,385 ( 20,651 ) December 31, 2023 Effect on present value of defined benefit obligations ( 17,562 ) 18,228 17,817 ( 17,262 )
Analysis of Timing of the Future Pension Payment	(f) As of December 31, 2023, the weighted average duration of that retirement plan is 9.7 years. The analysis of timing of the future pension payment was as follows: December 31, 2023 NT$000 Within 1 year 69,288 1-2 years 42,487 2-5 years 115,279 5-10 years 181,850 408,904

Capital surplus (Tables)

Capital surplus (Tables)	12 Months Ended
	Dec. 31, 2023
Capital surplus [Abstract]
Summary of Capital Surplus	2021 Share Others Total NT$000 NT$000 NT$000 January 1 6,043,483 7,304 6,050,787 Changes in associates accounted for using equity method — 4,834 4,834 December 31 6,043,483 12,138 6,055,621 2022 Share Others Total NT$000 NT$000 NT$000 January 1 6,043,483 12,138 6,055,621 Changes in associates accounted for using equity method — 152 152 December 31 6,043,483 12,290 6,055,773 2023 Share Others Total NT$000 NT$000 NT$000 January 1 6,043,483 12,290 6,055,773 December 31 6,043,483 12,290 6,055,773

Retained earnings (Tables)

Retained earnings (Tables)	12 Months Ended
	Dec. 31, 2023
Retained earnings [abstract]
Summary of Distribution Towards Legal Reserve and Cash Dividend	The appropriations and dividends per share are as follows: 2020 2021 2022 Amount Cash Amount Cash Amount Cash NT$000 NT$ NT$000 NT$ NT$000 NT$ Legal reserve 232,611 505,482 354,986 Special reserve ( 19,802 ) — — Cash dividend 1,599,928 2.20 3,127,133 4.30 1,672,652 2.30

Other equity interest (Tables)

Other equity interest (Tables)	12 Months Ended
	Dec. 31, 2023
Other Equity Interests [Abstract]
Summary of Other Equity Interest	2021 Financial statements Unrealized gain (loss) Total NT$000 NT$000 NT$000 January 1 ( 61,330 ) 194,716 133,386 Currency translation differences - The Company ( 24,695 ) — ( 24,695 ) Evaluation adjustment - The Company — 122,514 122,514 - Associates — 21,094 21,094 Evaluation adjustment related tax - The Company — ( 30,459 ) ( 30,459 ) December 31 ( 86,025 ) 307,865 221,840 2022 Financial statements Unrealized gain (loss) Total NT$000 NT$000 NT$000 January 1 ( 86,025 ) 307,865 221,840 Currency translation differences - The Company 68,656 — 68,656 Evaluation adjustment - The Company — ( 46,419 ) ( 46,419 ) - Associates — ( 28,353 ) ( 28,353 ) Evaluation adjustment related tax - The Company — 12,559 12,559 December 31 ( 17,369 ) 245,652 228,283 2023 Financial statements Unrealized gain (loss) on valuation of Equity directly related to non-current assets held for sale Total NT$000 NT$000 NT$000 NT$000 January 1 ( 17,369 ) 245,652 — 228,283 Currency translation differences - The Company 16,713 — — 16,713 - Non-current assets held for sale — — ( 43,094 ) ( 43,094 ) Evaluation adjustment - The Company — ( 217,785 ) — ( 217,785 ) - Associates — 12,605 — 12,605 Evaluation adjustment related tax - The Company — 51,638 — 51,638 December 31 ( 656 ) 92,110 ( 43,094 ) 48,360

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Dec. 31, 2023
Receivables from contracts with customers [abstract]
Summary of Revenue from Contracts with Customers	Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Revenue from contracts with customers 27,400,035 23,517,064 21,356,228
Summary of Contract Assets	The Group has recognized the following contract assets in relation to revenue from contracts with customers: January 1, 2022 December 31, 2022 December 31, 2023 NT$000 NT$000 NT$000 Contract assets 400,255 381,358 383,883

Other income (expenses), net (T

Other income (expenses), net (Tables)	12 Months Ended
	Dec. 31, 2023
Other income expenses net [abstract]
Summary of Other Income (Expenses), Net	Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Gain on disposal of property, plant and equipment, net 33,935 74,548 18,431 Gain on disposal of scrapped materials 52,254 35,381 44,662 Gain on disposal of items purchased on behalf of others 21,945 19,107 12,729 Gain from lease modifications 891 139 — Impairment loss on property, plant and equipment ( 4,843 ) ( 12,721 ) ( 9,236 ) Others 21,405 13,479 19,357 125,587 129,933 85,943

Interest income (Tables)

Interest income (Tables)	12 Months Ended
	Dec. 31, 2023
Disclosure of Interest Income [Abstract]
Disclosure of Interest Income	Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Bank deposits 8,772 56,612 191,265 Financial assets at amortized cost 1,187 587 1,861 Other interest income 21 — 63 9,980 57,199 193,189

Other income (Tables)

Other income (Tables)	12 Months Ended
	Dec. 31, 2023
Other Income [Abstract]
Summary of Other income	Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Rental income 17,326 35,848 48,264 Grant income 12,480 21,327 22,727 Dividend income 4,690 9,816 6,592 34,496 66,991 77,583

Other gains and losses (Tables)

Other gains and losses (Tables)	12 Months Ended
	Dec. 31, 2023
Disclosure of Other gains and losses [Abstract]
Summary of Other gains and losses	Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Foreign exchange (losses) gains, net ( 89,152 ) 448,097 78,170 Gain (loss) on valuation of financial assets at fair value 15,262 ( 69,404 ) 39,254 Reimbursement of ADSs service charge 2,284 2,412 2,121 Compensation income 1,524 174 20 Others 4,253 5,288 15,936 ( 65,829 ) 386,567 135,501

Finance costs (Tables)

Finance costs (Tables)	12 Months Ended
	Dec. 31, 2023
Finance costs [Abstract]
Summary of Finance Costs	Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Interest expense Bank loans 116,946 138,731 254,892 Lease liabilities 15,245 14,556 18,757 Others — 8 — Less: Amounts capitalized in qualifying assets ( 11,193 ) ( 10,856 ) ( 7,692 ) 120,998 142,439 265,957 Finance expense 10,186 10,840 433 131,184 153,279 266,390

Expenses by nature (Tables)

Expenses by nature (Tables)	12 Months Ended
	Dec. 31, 2023
Analysis of income and expense [abstract]
Summary of Expenses by nature	Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Raw materials and supplies used 5,518,145 4,512,527 3,991,490 Employee benefit expenses 6,757,888 6,466,303 5,836,068 Depreciation expenses 4,634,112 4,751,902 4,779,333 Others 5,053,088 4,699,586 4,926,828 21,963,233 20,430,318 19,533,719

Employee benefit expenses (Tabl

Employee benefit expenses (Tables)	12 Months Ended
	Dec. 31, 2023
Employee benefit expenses [Abstract]
Summary of Employee benefit expenses	Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Salaries 5,632,219 5,302,234 4,741,380 Directors’ remuneration 40,164 28,621 23,980 Labor and health insurance 424,901 449,223 432,568 Pension 200,014 205,671 195,359 Other personnel expenses 460,590 480,554 442,781 6,757,888 6,466,303 5,836,068 a) In accordance with the Company’s Articles of Incorporation, employees’ compensation is based on the current year’s earnings, which should first be used to cover accumulated deficits, if any, and then 10 % of the remaining balance distributed as employees’ compensation, including distributions to certain qualifying employees in affiliate companies, and no more than 0.5 % as directors’ remuneration. Subject to the Board of Directors’ approval, employees’ compensation may be made by way of cash or share issuance. Distribution of employees’ compensation and directors’ remuneration shall be presented and reported in the subsequent shareholders’ meeting. b) Based on profit as of the end of reporting period, for the years ended December 31, 2021, 2022 and 2023 , the employees’ compensation were accrued at NT$ 673,387 thousand, NT$ 447,303 thousand and 250,181 thousand, respectively; the directors’ remuneration were accrued at NT$ 25,690 thousand, NT$ 11,182 thousand and NT$ 6,255 thousand, respectively. c) For the year of 2022 , employees’ compensation and directors’ remuneration recognized were consistent with the amounts resolved in the Board of Directors’ meeting.

Income tax expense (Tables)

Income tax expense (Tables)	12 Months Ended
	Dec. 31, 2023
Income tax expense [abstract]
Major Components of Income Tax Expense	(a) Components of income tax expense: Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Current income tax: Current income tax on profits for the period 1,109,752 771,378 426,878 Income tax on unappropriated retained earnings 227,467 159,744 85,607 Prior year income tax overestimation ( 184,284 ) ( 255,935 ) ( 182,778 ) Total current income tax 1,152,935 675,187 329,707 Deferred income tax: Relating to origination and reversal of temporary differences ( 54,617 ) ( 87,012 ) ( 29,046 ) Income tax expense 1,098,318 588,175 300,661
Deferred Tax Charged to Other Comprehensive Income	(b) The income tax (charge)/credit relating to components of other comprehensive income are as follows: Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Unrealized gain (loss) on valuation of financial assets at 30,459 ( 12,559 ) ( 51,638 ) Remeasurement of defined benefit obligations ( 2,999 ) 44,447 2,140 27,460 31,888 ( 49,498 )
Reconciliation of Income Tax Expense and Accounting Profit Before Income Tax	b) Reconciliation of income tax expense and the accounting profit: Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Tax calculated based on profit before tax and statutory tax rate 1,207,605 804,086 451,676 Effects from adjustments based on regulation ( 152,618 ) ( 131,873 ) ( 74,094 ) Gain on investment in associates — 11,923 19,228 Prior year income tax overestimation ( 184,284 ) ( 255,935 ) ( 182,778 ) Income tax on unappropriated retained earnings 227,467 159,744 85,607 Effect of different tax rates in countries in which the Group operates 148 230 1,022 Income tax expense 1,098,318 588,175 300,661
Details of Deferred Tax Assets (Liabilities)	c) The amounts of deferred tax assets or liabilities resulting from temporary differences and investment tax credits are as follows: 2021 January 1 Recognized in Recognized December 31 NT$000 NT$000 NT$000 NT$000 Deferred tax assets Loss on inventories 15,963 8,354 — 24,317 Property, plant and equipment 36,401 235 — 36,636 Provisions 2,678 171 — 2,849 Deferred revenue 21,144 ( 6,506 ) — 14,638 Net defined benefit liability 98,921 ( 4,672 ) 2,999 97,248 Unrealized exchange losses 9,915 ( 7,754 ) — 2,161 Others 669 2,080 — 2,749 Total 185,691 ( 8,092 ) 2,999 180,598 Deferred tax liabilities Property, plant and equipment ( 255,484 ) 62,797 — ( 192,687 ) Financial assets at fair value through other ( 54,943 ) — ( 30,459 ) ( 85,402 ) Others — ( 88 ) — ( 88 ) Total ( 310,427 ) 62,709 ( 30,459 ) ( 278,177 ) Information presented on statements of Deferred tax assets 185,691 180,598 Deferred tax liabilities ( 310,427 ) ( 278,177 ) 2022 January 1 Recognized in Recognized December 31 NT$000 NT$000 NT$000 NT$000 Deferred tax assets Loss on inventories 24,317 ( 3,191 ) — 21,126 Property, plant and equipment 36,636 2,258 — 38,894 Provisions 2,849 10,010 — 12,859 Deferred revenue 14,638 ( 6,506 ) — 8,132 Net defined benefit liability 97,248 ( 4,368 ) ( 44,447 ) 48,433 Unrealized exchange losses 2,161 22,056 — 24,217 Others 2,749 2,876 — 5,625 Total 180,598 23,135 ( 44,447 ) 159,286 Deferred tax liabilities Property, plant and equipment ( 192,687 ) 75,713 — ( 116,974 ) Financial assets at fair value through other ( 85,402 ) — 12,559 ( 72,843 ) Gain on investment in associates — ( 11,923 ) — ( 11,923 ) Others ( 88 ) 87 — ( 1 ) Total ( 278,177 ) 63,877 12,559 ( 201,741 ) Information presented on statements of Deferred tax assets 180,598 159,286 Deferred tax liabilities ( 278,177 ) ( 201,741 ) 2023 January 1 Recognized in Recognized December 31 NT$000 NT$000 NT$000 NT$000 Deferred tax assets Loss on inventories 21,126 16,127 — 37,253 Property, plant and equipment 38,894 1,847 — 40,741 Provisions 12,859 1,518 — 14,377 Deferred revenue 8,132 ( 6,506 ) — 1,626 Net defined benefit liability 48,433 ( 4,236 ) ( 2,140 ) 42,057 Unrealized exchange losses 24,217 ( 6,032 ) — 18,185 Others 5,625 3,418 — 9,043 Total 159,286 6,136 ( 2,140 ) 163,282 Deferred tax liabilities Property, plant and equipment ( 116,974 ) 42,142 — ( 74,832 ) Financial assets at fair value through other ( 72,843 ) — 51,638 ( 21,205 ) Gain on investment in associates ( 11,923 ) ( 19,228 ) — ( 31,151 ) Others ( 1 ) ( 4 ) — ( 5 ) Total ( 201,741 ) 22,910 51,638 ( 127,193 ) Information presented on statements of Deferred tax assets 159,286 163,282 Deferred tax liabilities ( 201,741 ) ( 127,193 )

Earnings per share (Tables)

Earnings per share (Tables)	12 Months Ended
	Dec. 31, 2023
Earnings per share [abstract]
Income and Share Data Used in Basic and Diluted EPS Computations	Year ended December 31, 2021 Amount after income tax Weighted average Earnings Basic earnings per share NT$000 In thousands NT$ Profit attributable to equity holders of the Company 4,937,267 727,240 6.79 Diluted earnings per share Assumed conversion of all dilutive potential ordinary shares: Employees’ compensation 15,618 Profit attributable to equity holders of the Company 4,937,267 742,858 6.65 Year ended December 31, 2022 Amount after income tax Weighted average Earnings Basic earnings per share NT$000 In thousands NT$ Profit attributable to equity holders of the Company 3,439,697 727,240 4.73 Diluted earnings per share Assumed conversion of all dilutive potential ordinary shares: Employees’ compensation 15,406 Profit attributable to equity holders of the Company 3,439,697 742,646 4.63 Year ended December 31, 2023 Amount after income tax Weighted average Earnings Basic earnings per share NT$000 In thousands NT$ Profit attributable to equity holders of the Company 1,967,565 727,240 2.71 Diluted earnings per share Assumed conversion of all dilutive potential ordinary shares: Employees’ compensation 7,698 Profit attributable to equity holders of the Company 1,967,565 734,938 2.68

Supplemental cash flow inform_2

Supplemental cash flow information (Tables)	12 Months Ended
	Dec. 31, 2023
Statement of cash flows [abstract]
Partial Cash Paid for Investing Activities	Property, plant and equipment Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Purchase of property, plant and equipment 6,552,702 4,918,482 3,228,471 Add: Beginning balance of payable to equipment suppliers 1,145,359 1,816,555 1,405,931 Less: Ending balance of payable to equipment suppliers ( 1,816,555 ) ( 1,405,931 ) ( 1,196,181 ) Less: Ending balance of payable to equipment suppliers — — ( 58,549 ) Less: Transfer from other non-current assets — ( 629,737 ) ( 305,791 ) Cash paid during the year 5,881,506 4,699,369 3,073,881

Changes in liabilities from f_2

Changes in liabilities from financing activities (Tables)	12 Months Ended
	Dec. 31, 2023
Disclosure of reconciliation of liabilities arising from financing activities [abstract]
Reconciliation of Liabilities Arising from Financing Activities	2021 Short-term Long-term bank Guarantee Lease Total liabilities NT$000 NT$000 NT$000 NT$000 NT$000 January 1 — 7,733,565 21,670 870,495 8,625,730 Changes in cash flow from financing 731,751 1,652,332 ( 45 ) ( 289,668 ) 2,094,370 Adjustment of right-of-use assets — — — 255,179 255,179 Amortization of loan fees — 7,646 — — 7,646 Amortization of interest expense — 19,822 — 15,245 35,067 December 31 731,751 9,413,365 21,625 851,251 11,017,992 2022 Short-term Long-term bank Guarantee Lease Total liabilities NT$000 NT$000 NT$000 NT$000 NT$000 January 1 731,751 9,413,365 21,625 851,251 11,017,992 Changes in cash flow from financing ( 731,751 ) 4,513,672 ( 25 ) ( 237,869 ) 3,544,027 Adjustment of right-of-use assets — — — 292,464 292,464 Amortization of loan fees — 10,026 — — 10,026 Amortization of interest expense — 30,738 — 14,556 45,294 December 31 — 13,967,801 21,600 920,402 14,909,803 2023 Long-term bank Guarantee Lease Total liabilities NT$000 NT$000 NT$000 NT$000 January 1 13,967,801 21,600 920,402 14,909,803 Changes in cash flow from financing 907,306 ( 365 ) ( 293,383 ) 613,558 Adjustment of right-of-use assets — — 419,625 419,625 Amortization of interest expense 36,612 — 18,757 55,369 December 31 14,911,719 21,235 1,065,401 15,998,355

Related party transactions (Tab

Related party transactions (Tables)	12 Months Ended
	Dec. 31, 2023
Related party transactions [abstract]
Summary of Significant Related Party Transactions	b) Names of related parties and relationship Name Relationship Unimos Shanghai Associate JMC Associate Daypower Energy Associate Siliconware Precision Industries Co., Ltd. (“SPIL”) Entity that has significant influence over the Company c) Significant related party transactions (a) Payable to equipment suppliers December 31, 2022 December 31, 2023 NT$000 NT$000 Daypower Energy — 58,549 (b) Acquisition of property, plant and equipment Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 SPIL — — 35,261
Key Management Personnel Compensation	d) Key management personnel compensation Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Salaries and other short-term employee benefits 243,405 211,620 176,702 Post-employment compensation 2,156 2,197 2,158 245,561 213,817 178,860

Pledged assets (Tables)

Pledged assets (Tables)	12 Months Ended
	Dec. 31, 2023
Disclosure assets pledged as collateral [abstract]
Certain Assets Provided as Collateral Mainly for Long-term Bank Loans and Leases	Carrying amount Assets Purpose December 31, 2022 December 31, 2023 NT$000 NT$000 Non-current financial assets at amortized cost Lease and bank loan 37,362 37,411 Property, plant and equipment, net - Land Bank loan 452,738 454,738 - Buildings Bank loan 5,385,508 5,299,221 - Machinery and equipment Bank loan 8,204,983 8,173,618 14,080,591 13,964,988

Significant contingent liabil_2

Significant contingent liabilities and unrecognized contract commitments (Tables)	12 Months Ended
	Dec. 31, 2023
Capital commitments [abstract]
Capital Expenditures that are Contracted for, but not Provided for	b) Capital expenditures that are contracted for, but not provided for are as follows: December 31, 2022 December 31, 2023 NT$000 NT$000 Property, plant and equipment, net 1,703,841 1,940,740

Capital management (Tables)

Capital management (Tables)	12 Months Ended
	Dec. 31, 2023
Disclosure of objectives, policies and processes for managing capital [abstract]
Summary of Group Monitors Capital using Liabilities to Assets Ratio	The liabilities to assets ratio at December 31, 2022 and 2023 were as follows: December 31, 2022 December 31, 2023 NT$000 NT$000 Total liabilities 20,303,685 21,397,287 Total assets 44,942,945 46,160,484 Liabilities to assets ratio 45.18 % 46.35 %

Financial risk management and_2

Financial risk management and fair values of financial instruments (Tables)	12 Months Ended
	Dec. 31, 2023
Disclosure of detailed information about financial instruments [abstract]
Summary of Financial Instruments by Category	(a) Financial instruments by category December 31, 2022 December 31, 2023 NT$000 NT$000 Financial assets Financial assets at fair value through profit or loss Financial assets mandatorily measured at fair value 128,224 42,735 Financial assets at fair value through other Designation of equity instruments 338,102 120,317 Financial assets at amortized cost Cash and cash equivalents 9,896,604 12,354,035 Financial assets at amortized cost 136,093 78,477 Accounts receivable 4,381,563 5,326,381 Other receivables 131,863 44,576 Refundable deposits 21,771 20,707 15,034,220 17,987,228 Financial liabilities Financial liabilities at amortized cost Notes payable 132 484 Accounts payable 560,802 784,919 Other payables 3,796,481 3,479,045 Other payables – related parties — 58,549 Long-term bank loans (including current portion) 13,967,801 14,911,719 Lease liabilities (including current portion) 920,402 1,065,401 Guarantee deposits 21,600 21,235 19,267,218 20,321,352
Information on Assets and Liabilities Denominated in Foreign Currencies whose Values would be Materially Affected by Exchange Rate Fluctuations	The information on assets and liabilities denominated in foreign currencies whose values would be materially affected by the exchange rate fluctuations is as follows: December 31, 2022 Foreign Exchange Carrying amount (Foreign currency: functional currency) Financial assets Monetary items US$000 208,989 30.7100 6,418,052 JPY000 114,940 0.2324 26,712 RMB000 7,199 4.4080 31,733 Non-monetary items JPY000 1,454,830 0.2324 338,102 RMB000 927,037 4.4080 4,086,378 Financial liabilities Monetary items US$000 11,031 30.7100 338,762 JPY000 1,587,732 0.2324 368,989 December 31, 2023 Foreign Exchange Carrying amount (Foreign currency: functional currency) Financial assets Monetary items US$000 149,837 30.7050 4,600,745 JPY000 188,904 0.2172 41,030 RMB000 5,595 4.3270 24,210 Non-monetary items JPY000 553,946 0.2172 120,317 Financial liabilities Monetary items US$000 21,175 30.7050 650,178 JPY000 1,102,264 0.2172 239,412
Details of Exposure to Currency Risk Arising from Recognized Monetary Assets or Liabilities Denominated in a Currency Other Than Functional Currency	6. Analysis of foreign currency market risk arising from significant foreign exchange variations: Year ended December 31, 2021 Sensitivity analysis Change in Effect on profit Effect on other Financial assets Monetary items US$000 5 % 260,390 — JPY000 5 % 1,702 — RMB000 5 % 1,074 — Financial liabilities Monetary items US$000 5 % 73,410 — JPY000 5 % 13,103 — Year ended December 31, 2022 Sensitivity analysis Change in Effect on profit Effect on other Financial assets Monetary items US$000 5 % 320,903 — JPY000 5 % 1,336 — RMB000 5 % 1,587 — Financial liabilities Monetary items US$000 5 % 16,938 — JPY000 5 % 18,449 — Year ended December 31, 2023 Sensitivity analysis Change in Effect on profit Effect on other Financial assets Monetary items US$000 5 % 230,037 — JPY000 5 % 2,052 — RMB000 5 % 1,211 — Financial liabilities Monetary items US$000 5 % 32,509 — JPY000 5 % 11,971 —
Summary of Loss Rate Methodology	As of December 31, 2022 and 2023 the loss rate methodologies are as follows: December 31, 2022 Contract Accounts receivable Other receivables NT$000 NT$000 NT$000 Expected loss rate 0.060 % 0.060 % 0.060 % Total carrying amount 381,587 4,384,232 131,908 Loss allowance ( 229 ) ( 2,669 ) ( 45 ) December 31, 2023 Contract Accounts receivable Other receivables NT$000 NT$000 NT$000 Expected loss rate 0.045 % 0.045 % 0.045 % Total carrying amount 384,057 5,328,835 44,589 Loss allowance ( 174 ) ( 2,454 ) ( 13 )
Summary of Movements in Relation to Loss Allowance for Contract Assets, Accounts Receivable and Other Receivables	7. Under the simplified approach, movements in relation to loss allowance for contract assets, accounts receivable, and other receivables are as follows: 2021 Contract Accounts receivable Other receivables NT$000 NT$000 NT$000 January 1 ( 117 ) ( 1,620 ) ( 10 ) Provision for impairment loss ( 3 ) ( 290 ) ( 6 ) December 31 ( 120 ) ( 1,910 ) ( 16 ) 2022 Contract Accounts receivable Other receivables NT$000 NT$000 NT$000 January 1 ( 120 ) ( 1,910 ) ( 16 ) Provision for impairment loss ( 109 ) ( 759 ) ( 29 ) December 31 ( 229 ) ( 2,669 ) ( 45 ) 2023 Contract Accounts receivable Other receivables NT$000 NT$000 NT$000 January 1 ( 229 ) ( 2,669 ) ( 45 ) Reversal of impairment loss 55 215 32 December 31 ( 174 ) ( 2,454 ) ( 13 )
Maturity Profile of Non-derivative Financial Liabilities Based on Contracted Undiscounted Payments	December 31, 2022 Within 1 to 3 years 3 to 5 years Over Total NT$000 NT$000 NT$000 NT$000 NT$000 Non-derivative financial liabilities Long-term bank loans 1,699,165 5,675,288 5,354,335 1,914,280 14,643,068 Lease liabilities 174,460 182,767 57,057 704,503 1,118,787 Guarantee deposits — — — 21,600 21,600 1,873,625 5,858,055 5,411,392 2,640,383 15,783,455 December 31, 2023 Within 1 to 3 years 3 to 5 years Over Total NT$000 NT$000 NT$000 NT$000 NT$000 Non-derivative financial liabilities Long-term bank loans 2,469,744 7,506,844 4,273,199 1,330,797 15,580,584 Lease liabilities 267,759 250,104 57,856 681,975 1,257,694 Guarantee deposits — — — 21,235 21,235 2,737,503 7,756,948 4,331,055 2,034,007 16,859,513
Summary of Natures of Assets and Liabilities	i) The related information of natures of the assets and liabilities are as follows: December 31, 2022 Level 1 Level 2 Level 3 Total NT$000 NT$000 NT$000 NT$000 Assets Recurring fair value measurements Financial assets at fair value through profit or loss - Listed stocks 128,224 — — 128,224 Financial assets at fair value through other - Foreign unlisted stocks — — 338,102 338,102 128,224 — 338,102 466,326 December 31, 2023 Level 1 Level 2 Level 3 Total NT$000 NT$000 NT$000 NT$000 Assets Recurring fair value measurements Financial assets at fair value through profit or loss - Listed stocks 42,735 — — 42,735 Financial assets at fair value through other - Foreign unlisted stocks — — 120,317 120,317 42,735 — 120,317 163,052
Summary of Movements of Level 3	(d) The following table shows the movements of Level 3 for the years ended December 31, 2022 and 2023: Equity instruments 2022 2023 NT$000 NT$000 January 1 384,521 338,102 Gains or losses recognized in other comprehensive income Recorded as unrealized loss on valuation of financial assets ( 46,419 ) ( 217,785 ) Purchases — 12,500 Reclassified as investments accounted for using equity method — ( 12,500 ) December 31 338,102 120,317
Summary of Qualitative Information and Sensitivity Analysis of Changes in Significant Unobservable Inputs Under Valuation Model Used in Level 3 Fair Value Measurement	(f) The following is the qualitative information and sensitivity analysis of changes in significant unobservable inputs under valuation model used in Level 3 fair value measurement: Fair value as of Valuation Significant Range Relationship of inputs NT$000 Non-derivative equity Foreign unlisted stocks 338,102 Comparable companies Enterprise value to 4.82 The higher the multiple, the higher the fair value Discount for lack of 15.80 % The higher the discount for lack of marketability, the lower the fair value Fair value as of Valuation Significant Range Relationship of NT$000 Non-derivative equity Foreign unlisted stocks 120,317 Comparable companies Enterprise value to 8.23 The higher the multiple, the higher the fair value Price to book ratio multiple 1.64 The higher the multiple, the higher the fair value Discount for lack of 15.70 % The higher the discount for lack of marketability, the lower the fair value
Summary of Effect of Profit or Loss or of Other Comprehensive Income from Financial Assets Categorized	December 31, 2022 Recognized in Recognized in other Input Change Favorable Unfavorable Favorable Unfavorable NT$000 NT$000 NT$000 NT$000 Financial assets: Foreign unlisted stocks Enterprise value to ±1% — — 2,876 2,883 Discount for lack ±1% — — 3,990 4,039 — — 6,866 6,922 December 31, 2023 Recognized in Recognized in other Input Change Favorable Unfavorable Favorable Unfavorable NT$000 NT$000 NT$000 NT$000 Financial assets: Foreign unlisted stocks Enterprise value to ±1% — — 748 709 Price to book ratio ±1% — — 30 30 Discount for lack ±1% — — 1,453 1,413 — — 2,231 2,152

Segment information (Tables)

Segment information (Tables)	12 Months Ended
	Dec. 31, 2023
Disclosure of operating segments [abstract]
Financial Segment Information for Operating Segments	The segment information provided to the chief operating decision maker for the reportable segments is as follows: Year ended December 31, 2021 Testing Assembly LCDD Bumping Others Elimination Total NT$000 NT$000 NT$000 NT$000 NT$000 NT$000 NT$000 Revenue External customers 5,899,600 7,963,714 8,211,099 5,325,622 — — 27,400,035 Inter-segment — — — — 43,808 ( 43,808 ) — Total revenue 5,899,600 7,963,714 8,211,099 5,325,622 43,808 ( 43,808 ) 27,400,035 Operating profit (loss) 1,814,021 857,304 2,336,394 561,642 ( 6,987 ) 15 5,562,389 Depreciation expenses ( 921,999 ) ( 576,138 ) ( 2,579,150 ) ( 549,020 ) ( 7,805 ) — ( 4,634,112 ) Share of profit of — — — — 1,211,177 ( 585,444 ) 625,733 Interest income — — — — 9,980 — 9,980 Interest expense — — — — ( 120,998 ) — ( 120,998 ) Purchase of property, 1,841,359 1,553,475 2,748,697 408,751 420 — 6,552,702 Year ended December 31, 2022 Testing Assembly LCDD Bumping Others Elimination Total NT$000 NT$000 NT$000 NT$000 NT$000 NT$000 NT$000 Revenue External customers 5,243,997 6,705,898 7,288,642 4,278,527 — — 23,517,064 Inter-segment — — — — 50,600 ( 50,600 ) — Total revenue 5,243,997 6,705,898 7,288,642 4,278,527 50,600 ( 50,600 ) 23,517,064 Operating profit (loss) 1,253,477 ( 93,585 ) 1,795,741 268,159 ( 6,821 ) ( 292 ) 3,216,679 Depreciation expenses ( 1,042,455 ) ( 694,835 ) ( 2,505,297 ) ( 500,863 ) ( 8,452 ) — ( 4,751,902 ) Share of profit of — — — — 884,555 ( 430,840 ) 453,715 Interest income — — — — 57,199 — 57,199 Interest expense — — — — ( 142,439 ) — ( 142,439 ) Purchase of property, 1,086,682 957,790 2,677,489 196,521 — — 4,918,482 Year ended December 31, 2023 Testing Assembly LCDD Bumping Others Elimination Total NT$000 NT$000 NT$000 NT$000 NT$000 NT$000 NT$000 Revenue External customers 4,394,726 4,629,430 7,821,640 4,510,432 — — 21,356,228 Inter-segment — — — — 59,481 ( 59,481 ) — Total revenue 4,394,726 4,629,430 7,821,640 4,510,432 59,481 ( 59,481 ) 21,356,228 Operating profit (loss) 514,707 ( 1,180,481 ) 2,058,285 522,386 ( 6,194 ) ( 251 ) 1,908,452 Depreciation expenses ( 1,065,689 ) ( 722,462 ) ( 2,547,253 ) ( 435,709 ) ( 8,220 ) — ( 4,779,333 ) Share of profit of — — — — 420,393 ( 200,502 ) 219,891 Interest income — — — — 193,189 — 193,189 Interest expense — — — — ( 265,957 ) — ( 265,957 ) Purchase of property, 749,158 568,289 1,756,590 152,908 1,526 — 3,228,471
Schedule of information on products and services	e) Information on products and services Year ended December 31, 2021 2022 2023 NT$000 % NT$000 % NT$000 % Testing 5,899,600 22 5,243,997 22 4,394,726 20 Assembly 7,963,714 29 6,705,898 29 4,629,430 22 LCDD 8,211,099 30 7,288,642 31 7,821,640 37 Bumping 5,325,622 19 4,278,527 18 4,510,432 21 27,400,035 100 23,517,064 100 21,356,228 100
Geographic Information of Revenue	f) Geographical information Year ended December 31, 2021 2022 2023 NT$000 NT$000 NT$000 Revenue ROC 21,608,567 18,671,142 17,287,574 Japan 1,768,460 1,989,805 1,176,163 PRC 1,899,362 1,970,943 1,729,908 Singapore 1,630,733 390,488 676,088 Others 492,913 494,686 486,495 27,400,035 23,517,064 21,356,228 December 31, 2022 December 31, 2023 NT$000 NT$000 Non-current assets ROC 21,677,980 20,360,166 PRC 2,291 1,279 Others 576 6,122 21,680,847 20,367,567
Net Revenue from Customers Representing at Least 10% of Total Revenue	The information on the major customers which constituted more than 10% of the Group’s total revenue for the years ended December 31, 2021, 2022 and 2023 is as follows: Year ended December 31, 2021 2022 2023 NT$000 % NT$000 % NT$000 % Customers Customer A 5,681,277 21 4,705,064 20 5,251,529 25 Customer B 2,484,611 9 1,868,583 8 2,834,188 13 Customer M 2,832,088 10 2,278,645 10 1,320,905 6

Financial statements schedule_2

Financial statements schedule: valuation and qualifying accounts (Tables)	12 Months Ended
	Dec. 31, 2023
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Disclosure Of Details Of Valuation And Qualifying Accounts	43. Financial statements schedule: valuation and qualifying accounts January 1 Additions charged Deduction / December 31 NT$000 NT$000 NT$000 NT$000 Year 2021 Allowance for impairment of property, plant 182,002 4,843 ( 3,666 ) 183,179 Allowance for impairment of obsolescence 79,815 41,771 — 121,586 Provision for deficiency compensation 3,463 11,898 ( 11,080 ) 4,281 Sales for allowance 9,864 34,744 ( 34,759 ) 9,849 Year 2022 Allowance for impairment of property, plant 183,179 12,721 ( 1,433 ) 194,467 Allowance for impairment of obsolescence 121,586 — ( 15,956 ) 105,630 Provision for deficiency compensation 4,281 79,827 ( 57,465 ) 26,643 Sales for allowance 9,849 94,641 ( 67,367 ) 37,123 Year 2023 Allowance for impairment of property, plant 194,467 9,236 — 203,703 Allowance for impairment of obsolescence 105,630 80,633 — 186,263 Provision for deficiency compensation 26,643 21,495 ( 14,574 ) 33,564 Sales for allowance 37,123 112,488 ( 111,944 ) 37,667 For movements in loss allowance for contract assets, accounts receivable, and other receivables, please refer to Note 41 a).

Summary of Material Accountin_4

Summary of Material Accounting Policies - Summary of Ownership Interests in Subsidiaries (Detail)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
ChipMOS U.S.A., Inc. [member]
Disclosure of joint ventures [line items]
Name of investor	The Company	The Company
Main businesses	Marketing of semiconductors and electronic related products	Marketing of semiconductors and electronic related products
Location	San Jose, USA	San Jose, USA
Percentage of Ownership (%)	100%	100%
ChipMOS TECHNOLOGIES (BVI) LTD. [member]
Disclosure of joint ventures [line items]
Name of investor	The Company	The Company
Main businesses	Holding company	Holding company
Location	British Virgin Islands	British Virgin Islands
Percentage of Ownership (%)	100%	100%
ChipMOS SEMICONDUCTORS (Shanghai) LTD. [Member]
Disclosure of joint ventures [line items]
Name of investor	ChipMOS BVI	ChipMOS BVI
Main businesses	Marketing of semiconductors and electronic related products	Marketing of semiconductors and electronic related products
Location	Shanghai, People’s Republic of China (“PRC”)	Shanghai, People’s Republic of China (“PRC”)
Percentage of Ownership (%)	100%	100%

Summary of Material Accountin_5

Summary of Material Accounting Policies - Estimated Useful Life for Depreciation of Individual Assets (Detail)	12 Months Ended
	Dec. 31, 2023
Buildings [member] | Bottom of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful life of individual assets	1 year
Buildings [member] | Top of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful life of individual assets	51 years
Machinery and equipment [member] | Bottom of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful life of individual assets	1 year
Machinery and equipment [member] | Top of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful life of individual assets	20 years
Tools [member] | Bottom of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful life of individual assets	1 year
Tools [member] | Top of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful life of individual assets	4 years
Other equipment [member] | Bottom of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful life of individual assets	1 year
Other equipment [member] | Top of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful life of individual assets	7 years

Translation into U.S. Dollar _2

Translation into U.S. Dollar Amounts - Additional Information (Detail)	Dec. 31, 2023
Foreign exchange rates [abstract]
Foreign exchange rate from New Taiwan dollars to U.S. dollars at the noon buying rate in the City of New York for cable transfers as certified for customs purposes by the Federal Reserve Bank of New York	30.62

Cash and Cash Equivalents - Sum

Cash and Cash Equivalents - Summary of Cash and Cash Equivalents (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)
Cash and cash equivalents [abstract]
Cash on hand and petty cash	$ 450		$ 450
Checking accounts and demand deposits	1,434,939		2,248,954
Time deposits	10,918,646		7,647,200
Cash and cash equivalents	$ 12,354,035	$ 403,463	$ 9,896,604

Financial Assets at Fair Valu_3

Financial Assets at Fair Value Through Profit or Loss - Summary of Financial Assets at Fair Value Through Profit or Loss (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)
Financial Assets At Fair Value Through Profit Or Loss [line items]
Current financial assets mandatorily measured at fair value through profit or loss	$ 42,735	$ 1,396	$ 128,224
Listed stocks [member]
Financial Assets At Fair Value Through Profit Or Loss [line items]
Current financial assets mandatorily measured at fair value through profit or loss	53,747		171,988
Valuation adjustments [member]
Financial Assets At Fair Value Through Profit Or Loss [line items]
Current financial assets mandatorily measured at fair value through profit or loss	$ (11,012)		$ (43,764)

Financial Assets at Fair Valu_4

Financial Assets at Fair Value Through Profit or Loss - Summary of Amounts recognized in Profit or Loss in Relation to Financial Assets at Fair Value Through Profit or Loss (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Financial Assets At Fair Value Through Profit Or Loss [line items]
Financial assets mandatorily measured at fair value through profit or loss	$ 39,254	$ 1,282	$ (69,404)	$ 15,262
Foreign partnership interests [member]
Financial Assets At Fair Value Through Profit Or Loss [line items]
Financial assets mandatorily measured at fair value through profit or loss				(941)
Beneficiary certificates [member]
Financial Assets At Fair Value Through Profit Or Loss [line items]
Financial assets mandatorily measured at fair value through profit or loss	17,253		5,807	2,530
Listed stocks [member]
Financial Assets At Fair Value Through Profit Or Loss [line items]
Financial assets mandatorily measured at fair value through profit or loss	$ 22,001		$ (75,211)	$ 13,673

Financial Assets at Amortized_3

Financial Assets at Amortized Cost - Summary of Financial Assets at Amortized Cost (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)	Dec. 31, 2023 USD ($)
Financial Instruments At Amortised Cost Category [Line Items]
Time deposits	$ 41,066	$ 98,731		$ 1,341
Restricted bank deposits	37,411	37,362		$ 1,222
Interest income	1,861	587	$ 1,187
Time Deposits
Financial Instruments At Amortised Cost Category [Line Items]
Time deposits	41,066	98,731
Restricted Bank Deposits
Financial Instruments At Amortised Cost Category [Line Items]
Restricted bank deposits	$ 37,411	$ 37,362

Accounts receivable - Summary o

Accounts receivable - Summary of Accounts and notes receivable (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Jan. 01, 2022 TWD ($)
Disclosure of financial assets [Line Items]
Accounts receivable	$ 5,326,381	$ 173,951	$ 4,381,563
Accounts receivable [member]
Disclosure of financial assets [Line Items]
Accounts receivable	5,328,835		4,384,232	$ 6,344,246
Loss allowance [member]
Disclosure of financial assets [Line Items]
Accounts receivable	$ (2,454)		$ (2,669)

Accounts receivable - Additiona

Accounts receivable - Additional Information (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Jan. 01, 2022 TWD ($)
Disclosure of financial assets [Line Items]
Accounts receivable, net	$ 5,326,381	$ 173,951	$ 4,381,563
Accounts receivable [member]
Disclosure of financial assets [Line Items]
Accounts receivable, net	$ 5,328,835		$ 4,384,232	$ 6,344,246
Bottom of range [member]
Disclosure of financial assets [Line Items]
Credit term granted to customers	30 days
Top of range [member]
Disclosure of financial assets [Line Items]
Credit term granted to customers	90 days

Accounts receivable - Aging of

Accounts receivable - Aging of Accounts Receivable which are Past Due but not Impaired (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Jan. 01, 2022 TWD ($)
Disclosure of financial assets [Line Items]
Current trade receivables	$ 5,326,381	$ 173,951	$ 4,381,563
Accounts receivable [member]
Disclosure of financial assets [Line Items]
Current trade receivables	5,328,835		4,384,232	$ 6,344,246
Accounts receivable [member] | Current [member]
Disclosure of financial assets [Line Items]
Current trade receivables	5,326,523		4,357,073
Accounts receivable [member] | Within 1 month [member]
Disclosure of financial assets [Line Items]
Current trade receivables	2,089		$ 27,159
Accounts receivable [member] | 1-2 months
Disclosure of financial assets [Line Items]
Current trade receivables	$ 223

Inventories - Summary of Invent

Inventories - Summary of Inventories (Detail) - TWD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Disclosure of inventories [Line Items]
Raw materials	$ 2,568,648	$ 3,210,409
Gross carrying amount [member]
Disclosure of inventories [Line Items]
Raw materials	2,754,911	3,316,039
Allowance for impairment losses [member]
Disclosure of inventories [Line Items]
Raw materials	$ (186,263)	$ (105,630)

Inventories - Cost of Inventori

Inventories - Cost of Inventories Recognized as an Expense (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Analysis of income and expense [abstract]
Cost of revenue	$ 17,723,687		$ 18,611,515	$ 20,103,735
Loss on abandonment	2,483		9,448	552
Allowance for (reversal of) inventory valuation and obsolescence loss	80,633		(15,956)	41,770
Cost of revenue	$ 17,806,803	$ 581,542	$ 18,605,007	$ 20,146,057

Non-current Financial Assets _3

Non-current Financial Assets at Fair Value Through Other Comprehensive Income - Summary of Non-current Financial Assets at Fair Value Through Other Comprehensive Income (Detail) - TWD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Financial assets at fair value through other comprehensive income [line items]
Designation of equity instruments	$ 120,317	$ 338,102
Foreign unlisted stocks [member]
Financial assets at fair value through other comprehensive income [line items]
Designation of equity instruments	38,534	38,534
Valuation adjustments [member]
Financial assets at fair value through other comprehensive income [line items]
Designation of equity instruments	$ 81,783	$ 299,568

Non-current Financial Assets _4

Non-current Financial Assets at Fair Value Through Other Comprehensive Income - Additional Information (Detail) - TWD ($) shares in Thousands	1 Months Ended
	Apr. 30, 2023	Dec. 31, 2023
Non-current financial assets at fair value through other comprehensive income [Line Items]
Financial assets at fair value through other comprehensive income were pledged		$ 0
Daypower Energy [member] | Ordinary shares [member]
Non-current financial assets at fair value through other comprehensive income [Line Items]
Number of shares acquired	1,000
Amount of shares acquired value	$ 12,500,000
Acquired Percentage Of Shareholdings	10%

Non-current Financial Assets _5

Non-current Financial Assets at Fair Value Through Other Comprehensive Income - Summary Amounts recognized in other comprehensive income in relation to the financial assets at fair value through other comprehensive income (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Financial assets at fair value through other comprehensive income [abstract]
Foreign unlisted stocks	$ (217,785)	$ (7,113)	$ (46,419)	$ 122,514

Investments accounted for usi_3

Investments accounted for using equity method - Details of Investment in Associates (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)
Disclosure of associates [line items]
Carrying amount	$ 290,542	$ 9,489	$ 4,353,448
JMC ELECTRONICS CO., LTD. [member]
Disclosure of associates [line items]
Carrying amount	277,076		267,070
Unimos Shanghai [member]
Disclosure of associates [line items]
Carrying amount			$ 4,086,378
Daypower Energy [member]
Disclosure of associates [line items]
Carrying amount	$ 13,466

Investments accounted for usi_4

Investments accounted for using equity method - Additional Information (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)
Disclosure of associates [line items]
Carrying amount of investment in associates	$ 290,542	$ 9,489	$ 4,353,448
Individually Immaterial Associates [member]
Disclosure of associates [line items]
Carrying amount of investment in associates	290,542		4,353,448
JMC ELECTRONICS CO., LTD. [member]
Disclosure of associates [line items]
Investment in associates at fair value	303,780		249,000
Carrying amount of investment in associates	$ 277,076		$ 267,070

Investments accounted for usi_5

Investments accounted for using equity method - Summarized Financial Information for Investment in Material Associates (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Disclosure of associates [line items]
Other comprehensive income (loss), net of income tax	$ (170,976)	$ (5,584)	$ 184,329	$ 84,203
Total comprehensive income (loss) for the year	1,796,589	$ 58,674	3,624,026	5,021,470
Individually Immaterial Associates [member]
Disclosure of associates [line items]
Profit for the year from continuing operations	1,714		453,715	625,733
Other comprehensive income (loss), net of income tax	12,993		(28,254)	28,843
Total comprehensive income (loss) for the year	$ 14,707		$ 425,461	$ 654,576

Property, Plant and Equipment_3

Property, Plant and Equipment, Net - Summary of Property, Plant and Equipment, Net (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	$ 20,446,205		$ 20,111,121	$ 17,994,686
Additions	3,228,471		4,918,482	6,552,702
Disposals	(27,612)		(48,681)	(76,375)
Reclassifications	0		1,012	0
Depreciation expenses	(4,498,306)		(4,523,081)	(4,355,032)
Impairment losses	(9,236)	$ (302)	(12,721)	(4,843)
Exchange adjustments	(19)		73	(17)
Ending Balance	19,139,503	$ 625,065	20,446,205	20,111,121
Land [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	452,738		452,738	452,738
Additions	0		0	0
Disposals	0		0	0
Reclassifications	2,000		0	0
Depreciation expenses	0		0	0
Impairment losses	0		0	0
Exchange adjustments	0		0	0
Ending Balance	454,738		452,738	452,738
Buildings [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	5,385,508		4,343,556	4,092,286
Additions	1,303		3,780	1,345
Disposals	0		0	0
Reclassifications	469,597		1,503,432	673,208
Depreciation expenses	(557,187)		(465,260)	(423,283)
Impairment losses	0		0	0
Exchange adjustments	0		0	0
Ending Balance	5,299,221		5,385,508	4,343,556
Machinery and equipment [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	12,758,368		13,282,185	11,348,297
Additions	5,579		6,748	11,829
Disposals	(16,574)		(46,084)	(66,873)
Reclassifications	1,787,140		2,603,381	4,890,400
Depreciation expenses	(3,043,504)		(3,075,191)	(2,896,612)
Impairment losses	(9,236)		(12,721)	(4,843)
Exchange adjustments	0		50	(13)
Ending Balance	11,481,773		12,758,368	13,282,185
Tools [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	796,697		837,990	952,361
Additions	291		636	407
Disposals	(11,038)		(2,597)	(9,502)
Reclassifications	586,090		685,481	690,346
Depreciation expenses	(635,227)		(724,813)	(795,622)
Impairment losses	0		0	0
Exchange adjustments	0		0	0
Ending Balance	736,813		796,697	837,990
Other [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	548,694		511,723	509,397
Additions	1,376		0	189
Disposals	0		0	0
Reclassifications	226,610		294,765	241,656
Depreciation expenses	(262,388)		(257,817)	(239,515)
Impairment losses	0		0	0
Exchange adjustments	(19)		23	(4)
Ending Balance	514,273		548,694	511,723
Construction in progress and equipment to be inspected [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	504,200		682,929	639,607
Additions	3,219,922		4,907,318	6,538,932
Disposals	0		0	0
Reclassifications	(3,071,437)		(5,086,047)	(6,495,610)
Depreciation expenses	0		0	0
Impairment losses	0		0	0
Exchange adjustments	0		0	0
Ending Balance	652,685		504,200	682,929
Gross carrying amount [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	81,866,361		78,108,945	73,187,794
Ending Balance	84,341,575		81,866,361	78,108,945
Gross carrying amount [member] | Land [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	452,738		452,738	452,738
Ending Balance	454,738		452,738	452,738
Gross carrying amount [member] | Buildings [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	13,379,852		11,877,419	11,212,129
Ending Balance	13,850,418		13,379,852	11,877,419
Gross carrying amount [member] | Machinery and equipment [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	59,197,255		57,176,339	53,246,474
Ending Balance	60,650,428		59,197,255	57,176,339
Gross carrying amount [member] | Tools [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	5,716,357		5,574,316	5,451,547
Ending Balance	5,959,251		5,716,357	5,574,316
Gross carrying amount [member] | Other [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	2,615,959		2,345,204	2,185,299
Ending Balance	2,774,055		2,615,959	2,345,204
Gross carrying amount [member] | Construction in progress and equipment to be inspected [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	504,200		682,929	639,607
Ending Balance	652,685		504,200	682,929
Accumulated depreciation and impairment [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	(61,420,156)		(57,997,824)	(55,193,108)
Ending Balance	(65,202,072)		(61,420,156)	(57,997,824)
Accumulated depreciation and impairment [member] | Land [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	0		0	0
Ending Balance	0		0	0
Accumulated depreciation and impairment [member] | Buildings [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	(7,994,344)		(7,533,863)	(7,119,843)
Ending Balance	(8,551,197)		(7,994,344)	(7,533,863)
Accumulated depreciation and impairment [member] | Machinery and equipment [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	(46,438,887)		(43,894,154)	(41,898,177)
Ending Balance	(49,168,655)		(46,438,887)	(43,894,154)
Accumulated depreciation and impairment [member] | Tools [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	(4,919,660)		(4,736,326)	(4,499,186)
Ending Balance	(5,222,438)		(4,919,660)	(4,736,326)
Accumulated depreciation and impairment [member] | Other [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	(2,067,265)		(1,833,481)	(1,675,902)
Ending Balance	(2,259,782)		(2,067,265)	(1,833,481)
Accumulated depreciation and impairment [member] | Construction in progress and equipment to be inspected [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	0		0	0
Ending Balance	$ 0		$ 0	$ 0

Property, Plant and Equipment_4

Property, Plant and Equipment, Net - Capitalization Interest and Capitalization Interest Rate Applied Related to Property, Plant and Equipment (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disclosure of detailed information about property, plant and equipment [abstract]
Amount of interest capitalized	$ 7,692	$ 10,856	$ 11,193
Range of the interest rates for capitalization	1.4588%	1.0094%	1.1358%

Non-current assets held for s_3

Non-current assets held for sale - Additional Information (Details)	Dec. 21, 2023
Disclosure of subsidiaries [line items]
Percentage of owned equity investment approved to sell	45.0242%
Unimos Shanghai [member]
Disclosure of subsidiaries [line items]
Percentage of owned equity investment approved to sell	45.0242%

Non-current assets held for s_4

Non-current assets held for sale - Summary of Assets Held for Sale (Details) - Dec. 31, 2023 $ in Thousands, $ in Thousands	TWD ($)	USD ($)
Disclosure of subsidiaries [line items]
Investment accounted for using equity method in Unimos Shanghai	$ 4,278,658	$ 139,734
Unimos Shanghai [member]
Disclosure of subsidiaries [line items]
Investment accounted for using equity method in Unimos Shanghai	$ 4,278,658

Leasing arrangements - leasee -

Leasing arrangements - leasee - Additional Information (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Leasing arrangements lessee [line items]
Additions to right of use asset	$ 419,625	$ 308,550
Payments of lease liabilities	$ 351,063	$ 333,133	$ 448,290
Top of range [member]
Leasing arrangements lessee [line items]
Lease term	30 years
Top of range [member] | Land [member]
Leasing arrangements lessee [line items]
Lease term	30 years
Top of range [member] | Machinery and equipment [member]
Leasing arrangements lessee [line items]
Lease term	3 years
Bottom of range [member]
Leasing arrangements lessee [line items]
Lease term	2 years
Bottom of range [member] | Land [member]
Leasing arrangements lessee [line items]
Lease term	10 years
Bottom of range [member] | Machinery and equipment [member]
Leasing arrangements lessee [line items]
Lease term	2 years

Leasing arrangements - leasee_2

Leasing arrangements - leasee - summary of carrying amount of right-of-use assets and the depreciation expenses (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)	Dec. 31, 2023 USD ($)
Disclosure of quantitative information about right-of-use assets [line items]
Carrying amount	$ 1,037,502	$ 898,992		$ 33,883
Depreciation expenses	281,027	228,821	$ 279,080
Land [member]
Disclosure of quantitative information about right-of-use assets [line items]
Carrying amount	615,385	630,969
Depreciation expenses	21,524	21,904	20,486
Buildings [member]
Disclosure of quantitative information about right-of-use assets [line items]
Carrying amount	7,723	8,214
Depreciation expenses	11,738	10,861	9,870
Machinery and equipment [member]
Disclosure of quantitative information about right-of-use assets [line items]
Carrying amount	411,809	257,196
Depreciation expenses	245,304	194,059	247,090
Others [member]
Disclosure of quantitative information about right-of-use assets [line items]
Carrying amount	2,585	2,613
Depreciation expenses	$ 2,461	$ 1,997	$ 1,634

Leasing arrangements - leasee_3

Leasing arrangements - leasee - Summary of profit and loss accounts relating to lease contracts (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Items affecting profit or loss
Interest expense on lease liabilities	$ 18,757	$ 14,556	$ 15,245
Expense on short-term lease contracts	$ 55,944	$ 95,213	$ 143,791

Other Payables - Summary of Oth

Other Payables - Summary of Other Payables (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)
Trade and other current payables [abstract]
Payable to equipment suppliers	$ 1,196,181		$ 1,405,931
Salaries and bonuses payable	994,651		1,002,577
Employees' compensation payable	250,181		447,303
Pension payable	16,825		16,541
Directors' remuneration payable	6,255		11,182
Interest payable	9,625		7,768
Other expense payable	1,005,327		905,179
Other payables	$ 3,479,045	$ 113,620	$ 3,796,481

Long-term Bank Loans - Summary

Long-term Bank Loans - Summary of Long-term Bank Loans (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2023 USD ($)
Disclosure of detailed information about borrowings [Line Items]
Bank loans	$ 14,911,719	$ 13,967,801
Less: Unamortized interest on government granted bank loans	(60,592)	(88,330)
Less: Current portion (fee included)	(2,263,718)	(1,522,917)	$ (73,930)
Syndicated bank loans, excluding current portion	12,648,001	12,444,884	$ 413,063
Long-term bank loans [Member]
Disclosure of detailed information about borrowings [Line Items]
Unused credit lines of long-term bank loans	$ 7,232,770	$ 9,671,868
Gross carrying amount [member] | Minimum [Member]
Disclosure of detailed information about borrowings [Line Items]
Interest rate range	1.20%	1.075%	1.20%
Gross carrying amount [member] | Maximum [Member]
Disclosure of detailed information about borrowings [Line Items]
Interest rate range	1.75%	1.625%	1.75%
Gross carrying amount [member] | Government granted bank loans from March 2020 To October 2032 [Member]
Disclosure of detailed information about borrowings [Line Items]
Bank loans	$ 14,972,311	$ 14,056,131
Period and payment term	Borrowing period is from March 11, 2020 to October 15, 2032; interest is repayable monthly; principal is repayable monthly from March 15, 2023

Long-term Bank Loans - Addition

Long-term Bank Loans - Additional Information (Detail) $ in Millions		33 Months Ended
	May 15, 2018 TWD ($) Bank	Sep. 30, 2022 TWD ($)
Maximum [Member]
Disclosure of detailed information about borrowings [Line Items]
Maturity of loan		ten years
Minimum [Member]
Disclosure of detailed information about borrowings [Line Items]
Maturity of loan		seven years
Syndicated loan [member]
Disclosure of detailed information about borrowings [Line Items]
Number of banks in syndicate | Bank	11
Principal amount of loan	$ 12,000
Maturity of loan	five years
Government granted bank loans [Member]
Disclosure of detailed information about borrowings [Line Items]
Principal amount of loan		$ 23,730

Pensions - Additional Informati

Pensions - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($) Unit	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Disclosure of defined benefit plans [Line Items]
Weighted average duration of defined benefit obligation	9 years 8 months 12 days
Defined benefit plans expected contribution | $	$ 24,000
ChipMOS Shanghai [Member]
Disclosure of defined benefit plans [Line Items]
Employer contribution percentage	16%	16%	16%
Pension costs under defined contribution pension plans | $	$ 604	$ 380	$ 209
Defined benefit pension plan [Member]
Disclosure of defined benefit plans [Line Items]
Number of units accrued in first tranche | Unit	2
Duration of first tranche	first 15 years
Number of units accrued in second tranche | Unit	1
Duration of second tranche	Thereafter 15 years
Maximum number of units accruable under the pension plan | Unit	45
Benefit measurement period	6 months
Employer contribution percentage	2%
Defined contribution pension plan [member]
Disclosure of defined benefit plans [Line Items]
Employer contribution percentage	6%
Pension costs under defined contribution pension plans | $	$ 190,913	$ 201,606	$ 197,076

Pensions - Defined Benefit Plan

Pensions - Defined Benefit Plans Amounts Recognized in Statements of Financial Position (Detail) - TWD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Surplus (deficit) in plan [abstract]
Present value of defined benefit obligations	$ (744,191)	$ (759,548)
Fair value of plan assets	516,854	500,333
Net defined benefit liability	$ (227,337)	$ (259,215)	$ (503,288)	$ (511,651)

Pensions - Movements in Net Def

Pensions - Movements in Net Defined Benefit Liability (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disclosure of net defined benefit liability (asset) [Line Items]
Beginning balance	$ (259,215)	$ (503,288)	$ (511,651)
Current service cost	(133)	(257)	(237)
Interest (expense) income	(3,709)	(3,428)	(2,492)
Total	(263,057)	(506,973)	(514,380)
Return on plan assets (excluding amounts included in interest income or expense)	3,187	34,550	5,613
Impact on changes in demographic assumptions	14,216		(20,022)
Financial assumption movement effect	(7,103)	73,218	23,757
Experience adjustments	399	114,466	(24,347)
Gain (loss) on remeasurement, net defined benefit liability (asset)	10,699	222,234	(14,999)
Pension fund contribution	25,021	25,524	26,091
Ending balance	(227,337)	(259,215)	(503,288)
Present Value of Defined Benefit Obligation [member]
Disclosure of net defined benefit liability (asset) [Line Items]
Beginning balance	(759,548)	(959,677)	(943,391)
Current service cost	(133)	(257)	(237)
Interest (expense) income	(11,150)	(6,589)	(4,629)
Total	(770,831)	(966,523)	(948,257)
Impact on changes in demographic assumptions	14,216		(20,022)
Financial assumption movement effect	(7,103)	73,218	23,757
Experience adjustments	399	114,466	(24,347)
Gain (loss) on remeasurement, net defined benefit liability (asset)	7,512	187,684	(20,612)
Paid pension	19,128	19,291	9,192
Ending balance	(744,191)	(759,548)	(959,677)
Fair Value of Plan Assets [member]
Disclosure of net defined benefit liability (asset) [Line Items]
Beginning balance	500,333	456,389	431,740
Interest (expense) income	7,441	3,161	2,137
Total	507,774	459,550	433,877
Return on plan assets (excluding amounts included in interest income or expense)	3,187	34,550	5,613
Gain (loss) on remeasurement, net defined benefit liability (asset)	3,187	34,550	5,613
Pension fund contribution	25,021	25,524	26,091
Paid pension	(19,128)	(19,291)	(9,192)
Ending balance	$ 516,854	$ 500,333	$ 456,389

Pensions - Principal Actuarial

Pensions - Principal Actuarial Assumptions Used and Sensitivity Analysis of Present Value of Defined Benefit Obligation Effected by Changes of Principal Actuarial Assumptions (Detail)	Dec. 31, 2023	Dec. 31, 2022
Disclosure of sensitivity analysis for actuarial assumptions [abstract]
Discount rate	1.40%	1.50%
Future salary increases	3.50%	3.50%

Pensions - Sensitivity Analysis

Pensions - Sensitivity Analysis of Present Value of Defined Benefit Obligations Effected by Changes of Significant Actuarial Assumptions (Detail) - TWD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Actuarial assumption of discount rates [member]
Disclosure of sensitivity analysis for actuarial assumptions [Line Items]
Percentage increase in assumption	0.25%	0.25%
Effect on present value of defined benefit obligations due to increase in assumption	$ (17,562)	$ (20,992)
Percentage decrease in assumption	0.25%	0.25%
Effect on present value of defined benefit obligations due to decrease in assumption	$ 18,228	$ 21,860
Actuarial assumption of expected rates of salary increases [member]
Disclosure of sensitivity analysis for actuarial assumptions [Line Items]
Percentage increase in assumption	0.25%	0.25%
Effect on present value of defined benefit obligations due to increase in assumption	$ 17,817	$ 21,385
Percentage decrease in assumption	0.25%	0.25%
Effect on present value of defined benefit obligations due to decrease in assumption	$ (17,262)	$ (20,651)

Pensions - Analysis of Timing o

Pensions - Analysis of Timing of the Future Pension Payment (Detail) $ in Thousands	Dec. 31, 2023 TWD ($)
Disclosure of net defined benefit liability (asset) [Line Items]
Defined benefit plan expected future pension payments	$ 408,904
Within 1 year [member]
Disclosure of net defined benefit liability (asset) [Line Items]
Defined benefit plan expected future pension payments	69,288
1-2 years [member]
Disclosure of net defined benefit liability (asset) [Line Items]
Defined benefit plan expected future pension payments	42,487
2-5 years [member]
Disclosure of net defined benefit liability (asset) [Line Items]
Defined benefit plan expected future pension payments	115,279
5-10 years [member]
Disclosure of net defined benefit liability (asset) [Line Items]
Defined benefit plan expected future pension payments	$ 181,850

Capital stock - Additional Info

Capital stock - Additional Information (Detail) $ / shares in Units, $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($) $ / shares shares	Dec. 31, 2023 USD ($) shares	Dec. 31, 2022 TWD ($) shares	Dec. 31, 2021 shares
Disclosure of classes of share capital [line items]
Ordinary shares par value | $ / shares	$ 10
Number of shares outstanding	727,240,000	727,240,000	727,240,000	727,240,000
Authorised capital | $	$ 9,700,000
Number of shares authorized	970,000,000	970,000,000
Paid in capital	$ 7,272,401	$ 237,505	$ 7,272,401
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Number of shares outstanding	84,699,000	84,699,000
American depositary shares [member]
Disclosure of classes of share capital [line items]
Number of shares represented by each unit of ADS	20
Number of shares outstanding	4,234,970	4,234,970

Capital Surplus - Details of Ca

Capital Surplus - Details of Capital Surplus (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Capital surplus [line items]
Changes in associates accounted for using equity method	$ 152	$ 4,834
Ending balance	6,055,773
Capital surplus [member]
Capital surplus [line items]
Beginning balance	6,055,621	6,050,787
Changes in associates accounted for using equity method	152	4,834
Ending balance	6,055,773	6,055,621
Capital surplus [member] | Share premium [member]
Capital surplus [line items]
Beginning balance	6,043,483	6,043,483
Ending balance	6,043,483	6,043,483
Capital surplus [member] | Others [member]
Capital surplus [line items]
Beginning balance	12,138	7,304
Changes in associates accounted for using equity method	152	4,834
Ending balance	$ 12,290	$ 12,138

Retained Earnings - Details of

Retained Earnings - Details of Retained Earnings (Detail) - TWD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Legal reserve [member]
Disclosure of analysis of other comprehensive income by item [line items]
Appropriation of retained earnings	$ 354,986	$ 505,482	$ 232,611
Special Reserve [Member]
Disclosure of analysis of other comprehensive income by item [line items]
Appropriation of retained earnings			(19,802)
Cash Dividend [Member]
Disclosure of analysis of other comprehensive income by item [line items]
Appropriation of retained earnings	$ 1,672,652	$ 3,127,133	$ 1,599,928
Cash dividend, cash distribution per share	$ 2.3	$ 4.3	$ 2.2

Other equity interest - Summary

Other equity interest - Summary of Other Equity Interest (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Disclosure of Other Equity Interest [Line Items]
Beginning balance	$ 228,283
Evaluation adjustment - The Company	(217,785)	$ (7,113)	$ (46,419)	$ 122,514
Ending balance	48,360	$ 1,579	228,283
Financial statements translation differences of foreign operations [member]
Disclosure of Other Equity Interest [Line Items]
Beginning balance	(17,369)		(86,025)	(61,330)
Currency translation differences - The company	16,713		68,656	(24,695)
Ending balance	(656)		(17,369)	(86,025)
Unrealized gain (loss) on valuation of financial assets at fair value through other comprehensive income [member]
Disclosure of Other Equity Interest [Line Items]
Beginning balance	245,652		307,865	194,716
Evaluation adjustment - The Company	(217,785)		(46,419)	122,514
Evaluation adjustment - Associates	12,605		(28,353)	21,094
Evaluation adjustment related tax - The Company	51,638		12,559	(30,459)
Ending balance	92,110		245,652	307,865
Equity directly related to non-current assets held for sale [member]
Disclosure of Other Equity Interest [Line Items]
Currency translation differences - Non-current assets held for sale	(43,094)
Ending balance	(43,094)
Other equity interest [member]
Disclosure of Other Equity Interest [Line Items]
Beginning balance	228,283		221,840	133,386
Currency translation differences - The company	16,713		68,656	(24,695)
Currency translation differences - Non-current assets held for sale	(43,094)
Evaluation adjustment - The Company	(217,785)		(46,419)	122,514
Evaluation adjustment - Associates	12,605		(28,353)	21,094
Evaluation adjustment related tax - The Company	51,638		12,559	(30,459)
Ending balance	$ 48,360		$ 228,283	$ 221,840

Revenue - Summary of Revenue Fr

Revenue - Summary of Revenue From Contracts with Customers (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Receivables from contracts with customers [abstract]
Revenue from contracts with customers	$ 21,356,228	$ 23,517,064	$ 27,400,035

Revenue - Summary of Contract A

Revenue - Summary of Contract Assets (Detail) - TWD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Jan. 01, 2022
Disclosure Of Contract Assets In Relation To Revenue [Abstract]
Contract assets	$ 383,883	$ 381,358	$ 400,255

Other Income (Expenses), Net -

Other Income (Expenses), Net - Summary of Other Income (Expenses), Net (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Analysis of income and expense [abstract]
Gain on disposal of property, plant and equipment, net	$ 18,431		$ 74,548	$ 33,935
Gain on disposal of scrapped materials	44,662		35,381	52,254
Gain on disposal of items purchased on behalf of others	12,729		19,107	21,945
Gains from lease modifications			139	891
Impairment loss on property, plant and equipment	(9,236)	$ (302)	(12,721)	(4,843)
Others	19,357		13,479	21,405
Other operating income (expense), Total	$ 85,943	$ 2,807	$ 129,933	$ 125,587

Interest income - Disclosure of

Interest income - Disclosure of interest income (Details) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Disclosure of Interest Income [Abstract]
Bank deposits	$ 191,265		$ 56,612	$ 8,772
Financial assets at amortized cost	1,861		587	1,187
Other interest income	63			21
Interest income	$ 193,189	$ 6,309	$ 57,199	$ 9,980

Other Income - Summary of Other

Other Income - Summary of Other income (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Analysis of other income [Abstract]
Rental income	$ 48,264	$ 35,848	$ 17,326
Grant income	22,727	21,327	12,480
Dividend income	6,592	9,816	4,690
Other non-operating income (expenses), net	$ 77,583	$ 66,991	$ 34,496

Other gains and losses - Summar

Other gains and losses - Summary of Other gains and losses (Details) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Disclosure of Other gains and losses [Abstract]
Foreign exchange (losses) gains, net	$ 78,170		$ 448,097	$ (89,152)
Gain (loss) on valuation of financial assets at fair value through profit or loss	39,254	$ 1,282	(69,404)	15,262
Reimbursement of ADSs service charge	2,121		2,412	2,284
Compensation income	20		174	1,524
Others	15,936		5,288	4,253
Total	$ 135,501	$ 4,425	$ 386,567	$ (65,829)

Finance Costs - Summary of Fina

Finance Costs - Summary of Finance Costs (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Analysis of Finance Costs [abstract]
Bank loans	$ 254,892		$ 138,731	$ 116,946
Lease liabilities	18,757		14,556	15,245
Others			8
Less: Amounts capitalized in qualifying assets	(7,692)		(10,856)	(11,193)
Interest expense	265,957		142,439	120,998
Finance expense	433		10,840	10,186
Finance costs	$ 266,390	$ 8,700	$ 153,279	$ 131,184

Expenses by nature - Summary of

Expenses by nature - Summary of Expenses by nature (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Analysis of income and expense [abstract]
Raw materials and supplies used	$ 3,991,490	$ 4,512,527	$ 5,518,145
Employee benefit expenses	5,836,068	6,466,303	6,757,888
Depreciation expenses	4,779,333	4,751,902	4,634,112
Others	4,926,828	4,699,586	5,053,088
Total operating costs and expenses	$ 19,533,719	$ 20,430,318	$ 21,963,233

Employee benefit expenses - Sum

Employee benefit expenses - Summary of Employee benefit expenses (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Classes of employee benefits expense [abstract]
Salaries	$ 4,741,380	$ 5,302,234	$ 5,632,219
Directors' remuneration	23,980	28,621	40,164
Labor and health insurance	432,568	449,223	424,901
Pension	195,359	205,671	200,014
Other personnel expenses	442,781	480,554	460,590
Total Employee benefit expenses	$ 5,836,068	$ 6,466,303	$ 6,757,888

Employee benefit expenses - Add

Employee benefit expenses - Additional Information (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disclosure of defined benefit plans [Line Items]
Accrued Employee Compensation	$ 250,181	$ 447,303	$ 673,387
Accrued Directors remuneration	$ 6,255	$ 11,182	$ 25,690
Defined benefit pension plan [Member]
Disclosure of defined benefit plans [Line Items]
Employees' compensation distribution rate	10%
Director remuneration rate no more than	0.50%

Income Tax Expense - Additional

Income Tax Expense - Additional Information (Detail) - TWD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Disclosure of income tax expense [Line Items]
Taxable temporary differences not recognized as deferred tax liabilities	$ 1,245,171	$ 1,080,272

Income Tax Expense - Major Comp

Income Tax Expense - Major Components of Income Tax Expense (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Current income tax:
Current income tax on profits for the period	$ 426,878		$ 771,378	$ 1,109,752
Income tax on unappropriated retained earnings	85,607		159,744	227,467
Prior year income tax overestimation	(182,778)		(255,935)	(184,284)
Total current income tax	329,707		675,187	1,152,935
Deferred income tax:
Relating to origination and reversal of temporary differences	(29,046)		(87,012)	(54,617)
Income tax expense	$ 300,661	$ 9,819	$ 588,175	$ 1,098,318

Income Tax Expense - Deferred T

Income Tax Expense - Deferred Tax Charged to Other Comprehensive Income (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Income tax relating to components of other comprehensive income [abstract]
Unrealized gain (loss) on valuation of financial assets at fair value through other comprehensive income	$ (51,638)		$ (12,559)	$ 30,459
Remeasurement of defined benefit obligations	2,140		44,447	(2,999)
Total	$ (49,498)	$ (1,617)	$ 31,888	$ 27,460

Income Tax Expense - Reconcilia

Income Tax Expense - Reconciliation of Income Tax Expense and Accounting Profit Before Income Tax (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Reconciliation of income tax expense and accounting profit before income tax [abstract]
Tax calculated based on profit before tax and statutory tax rate	$ 451,676		$ 804,086	$ 1,207,605
Effects from adjustments based on regulation	(74,094)		(131,873)	(152,618)
Gain on investment in associates	19,228		11,923
Prior year income tax overestimation	(182,778)		(255,935)	(184,284)
Income tax on unappropriated retained earnings	85,607		159,744	227,467
Effect of different tax rates in countries in which the Group operates	1,022		230	148
Income tax expense	$ 300,661	$ 9,819	$ 588,175	$ 1,098,318

Income Tax Expense - Details of

Income Tax Expense - Details of Deferred Tax Assets (Liabilities) (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2020 TWD ($)
Disclosure of the detail of deferred tax assets and liabilities [line items]
Deferred tax assets	$ 163,282	$ 159,286	$ 180,598	$ 5,333	$ 185,691
Deferred tax liabilities	(127,193)	(201,741)	(278,177)	$ (4,154)	$ (310,427)
Deferred tax assets unrealized loss on inventories [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	21,126	24,317	15,963
Recognized in profit or loss	16,127	(3,191)	8,354
Ending balance	37,253	21,126	24,317
Property, plant and equipment, deferred tax assets [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	38,894	36,636	36,401
Ending balance	40,741	38,894	36,636
Provisions [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	12,859	2,849	2,678
Recognized in profit or loss	1,518	10,010	171
Ending balance	14,377	12,859	2,849
Deferred tax assets deferred revenue [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	8,132	14,638	21,144
Recognized in profit or loss	(6,506)	(6,506)	(6,506)
Ending balance	1,626	8,132	14,638
Net defined benefit liability [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	48,433	97,248	98,921
Recognized in profit or loss	(4,236)	(4,368)	(4,672)
Recognized in other comprehensive income	(2,140)	(44,447)	2,999
Ending balance	42,057	48,433	97,248
Unrealized exchange losses deferred tax assets [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	24,217	2,161	9,915
Recognized in profit or loss	(6,032)	22,056	(7,754)
Ending balance	18,185	24,217	2,161
Others [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	5,625	2,749	669
Recognized in profit or loss	3,418	2,876	2,080
Ending balance	9,043	5,625	2,749
Deferred tax asset [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	159,286	180,598	185,691
Recognized in profit or loss	6,136	23,135	(8,092)
Recognized in other comprehensive income	(2,140)	(44,447)	2,999
Ending balance	163,282	159,286	180,598
Property, plant and equipment, deferred tax liabilities [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	(116,974)	(192,687)	(255,484)
Recognized in profit or loss	42,142	75,713	62,797
Ending balance	(74,832)	(116,974)	(192,687)
Property, plant and equipment [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Recognized in profit or loss	1,847	2,258	235
Financial assets at fair value through other comprehensive income [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	(72,843)	(85,402)	(54,943)
Recognized in other comprehensive income	51,638	12,559	(30,459)
Ending balance	(21,205)	(72,843)	(85,402)
Gain on investment in associates [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	(11,923)
Recognized in profit or loss	(19,228)	(11,923)
Ending balance	(31,151)	(11,923)
Others [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	(1)	(88)
Recognized in profit or loss	(4)	87	(88)
Ending balance	(5)	(1)	(88)
Deferred tax liabilities [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	(201,741)	(278,177)	(310,427)
Recognized in profit or loss	22,910	63,877	62,709
Recognized in other comprehensive income	51,638	12,559	(30,459)
Ending balance	$ (127,193)	$ (201,741)	$ (278,177)

Earnings Per Share - Income and

Earnings Per Share - Income and Share Data Used in Basic and Diluted EPS Computations (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 $ / shares	Dec. 31, 2023 TWD ($) $ / shares shares	Dec. 31, 2022 TWD ($) $ / shares shares	Dec. 31, 2021 TWD ($) $ / shares shares
Basic earnings per share, amount after tax
Equity holders of the Company - Amount after tax | $		$ 1,967,565	$ 3,439,697	$ 4,937,267
Diluted earnings per share, amount after tax
Equity holders of the Company - Amount after tax | $		$ 1,967,565	$ 3,439,697	$ 4,937,267
Weighted average number of ordinary shares outstanding		727,240	727,240	727,240
Diluted earnings per share, weighted-average number of ordinary shares outstanding
Employees' compensation		7,698	15,406	15,618
Weighted average number of ordinary shares outstanding		734,938	742,646	742,858
Ordinary shares [member]
Basic earnings per share
Equity holders of the Company - Earnings per share | (per share)	$ 0.09	$ 2.71	$ 4.73	$ 6.79
Diluted earnings per share
Diluted earnings (loss) per share | (per share)	$ 0.09	$ 2.68	$ 4.63	$ 6.65

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information - Partial Cash Paid for Investing Activities (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Supplemental cash flow information [line items]
Purchase of property, plant and equipment	$ 3,228,471		$ 4,918,482	$ 6,552,702
Add: Beginning balance of payable to equipment suppliers	1,405,931		1,816,555	1,145,359
Less: Ending balance of payable to equipment suppliers	(1,196,181)		(1,405,931)	(1,816,555)
Less: Transfer from other non-current assets	(305,791)		(629,737)
Cash paid during the year	3,073,881	$ 100,389	$ 4,699,369	$ 5,881,506
Related parties [member]
Supplemental cash flow information [line items]
Less: Ending balance of payable to equipment suppliers	$ (58,549)

Changes in liabilities from f_3

Changes in liabilities from financing activities - Reconciliation of Liabilities Arising from Financing Activities (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	$ 14,909,803	$ 11,017,992	$ 8,625,730
Changes in cash flow from financing activities	613,558	3,544,027	2,094,370
Adjustment of right-of-use assets	419,625	292,464	255,179
Amortization of loan fees		10,026	7,646
Amortization of interest expense	55,369	45,294	35,067
Ending balance	15,998,355	14,909,803	11,017,992
Short-term bank loans [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance		731,751
Changes in cash flow from financing activities		(731,751)	731,751
Ending balance			731,751
Long-term bank loans (include the current portion) [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	13,967,801	9,413,365	7,733,565
Changes in cash flow from financing activities	907,306	4,513,672	1,652,332
Amortization of loan fees		10,026	7,646
Amortization of interest expense	36,612	30,738	19,822
Ending balance	14,911,719	13,967,801	9,413,365
Guarantee deposits [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	21,600	21,625	21,670
Changes in cash flow from financing activities	(365)	(25)	(45)
Ending balance	21,235	21,600	21,625
Lease liabilities [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	920,402	851,251	870,495
Changes in cash flow from financing activities	(293,383)	(237,869)	(289,668)
Adjustment of right-of-use assets	419,625	292,464	255,179
Amortization of interest expense	18,757	14,556	15,245
Ending balance	$ 1,065,401	$ 920,402	$ 851,251

Related Party Transactions - Su

Related Party Transactions - Summary of Significant Related Party Transactions (Detail) - 12 months ended Dec. 31, 2023 $ in Thousands, $ in Thousands	TWD ($)	USD ($)
Disclosure of transactions between related parties [Line Items]
Payable to equipment suppliers	$ 58,549	$ 1,912
Unimos Shanghai [member]
Disclosure of transactions between related parties [Line Items]
Relationship	Associate
JMC ELECTRONICS CO., LTD. [member]
Disclosure of transactions between related parties [Line Items]
Relationship	Associate
Daypower Energy [member]
Disclosure of transactions between related parties [Line Items]
Relationship	Associate
Payable to equipment suppliers	$ 58,549
Siliconware Precision Industries Co., Ltd. [member]
Disclosure of transactions between related parties [Line Items]
Relationship	Entity that has significant influence over the Company
Acquisition of property, plant and equipment	$ 35,261

Related Party Transactions - Ke

Related Party Transactions - Key Management Personnel Compensation (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disclosure of transactions between related parties [abstract]
Salaries and other short-term employee benefits	$ 176,702	$ 211,620	$ 243,405
Post-employment compensation	2,158	2,197	2,156
Total key management personnel compensation	$ 178,860	$ 213,817	$ 245,561

Pledged assets - Certain Assets

Pledged assets - Certain Assets Provided as Collateral Mainly for Long-term Bank Loans and Leases (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Disclosure assets pledged as collateral [Line Items]
Purpose	Lease and bank loan
Non-current financial assets at amortized cost	$ 37,411	$ 37,362
Assets pledged as collateral for liabilities	$ 13,964,988	14,080,591
Land [member]
Disclosure assets pledged as collateral [Line Items]
Purpose	Bank loan
Property, plant and equipment, net	$ 454,738	452,738
Buildings [member]
Disclosure assets pledged as collateral [Line Items]
Purpose	Bank loan
Property, plant and equipment, net	$ 5,299,221	5,385,508
Machinery and equipment [member]
Disclosure assets pledged as collateral [Line Items]
Purpose	Bank loan
Property, plant and equipment, net	$ 8,173,618	$ 8,204,983

Significant contingent liabil_3

Significant contingent liabilities and unrecognized contract commitments - Additional Information (Detail) - TWD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Capital commitments [abstract]
Amounts guaranteed by the financial institutions	$ 71,900	$ 135,600

Significant contingent liabil_4

Significant contingent liabilities and unrecognized contract commitments - Capital Expenditures that are Contracted for, but not Provided for (Detail) - TWD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Disclosure of detailed information about property, plant and equipment [abstract]
Property plant and equipment, Contracted capital expenditures	$ 1,940,740	$ 1,703,841

Significant events after the _2

Significant events after the reporting period - Additional Information (Detail)	Dec. 21, 2023
Significant events after the reporting period [Abstract]
Proportion of subsidiary owned equity investment accounted for using equity method	45.0242%

Capital Management - Percentage

Capital Management - Percentages of Liabilities to Assets Ratio Used for Monitoring Capital (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)
Disclosure of objectives, policies and processes for managing capital [abstract]
Total liabilities	$ 21,397,287	$ 698,801	$ 20,303,685
Total assets	$ 46,160,484	$ 1,507,527	$ 44,942,945
Liabilities to assets ratio	46.35%	46.35%	45.18%

Financial Risk Management and_3

Financial Risk Management and Fair Values of Financial Instruments - Summary of Financial Instruments by Category (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)
Financial assets at fair value through profit or loss
Financial assets mandatorily measured at fair value through profit or loss	$ 42,735		$ 128,224
Financial assets at fair value through other comprehensive income
Designation of equity instruments	120,317		338,102
Financial assets at amortized cost
Cash and cash equivalents	12,354,035	$ 403,463	9,896,604
Financial assets at amortized cost	78,477		136,093
Accounts receivable	5,326,381	173,951	4,381,563
Other receivables	44,576	1,456	131,863
Refundable deposits	20,707	676	21,771
Financial assets	17,987,228		15,034,220
Financial liabilities at amortized cost
Notes payable	484	16	132
Accounts payable	784,919	25,634	560,802
Other payables	3,479,045	113,620	3,796,481
Other payables - related parties	58,549	1,912
Long-term bank loans (including current portion)	14,911,719		13,967,801
Lease liabilities (including current portion)	1,065,401		920,402
Guarantee deposits	21,235	$ 694	21,600
Financial liabilities	$ 20,321,352		$ 19,267,218

Financial Risk Management and_4

Financial Risk Management and Fair Values of Financial Instruments - Information on Assets and Liabilities Denominated in Foreign Currencies whose Values would be Materially Affected by Exchange Rate Fluctuations (Detail) ¥ in Thousands, ¥ in Thousands, $ in Thousands, $ in Thousands	Dec. 31, 2023 TWD ($) $ / ¥ $ / $ $ / ¥	Dec. 31, 2023 USD ($) $ / ¥ $ / $ $ / ¥	Dec. 31, 2023 JPY (¥) $ / ¥ $ / $ $ / ¥	Dec. 31, 2023 CNY (¥) $ / ¥ $ / $ $ / ¥	Dec. 31, 2022 TWD ($) $ / ¥ $ / $ $ / ¥	Dec. 31, 2022 USD ($) $ / ¥ $ / $ $ / ¥	Dec. 31, 2022 JPY (¥) $ / ¥ $ / $ $ / ¥	Dec. 31, 2022 CNY (¥) $ / ¥ $ / $ $ / ¥
Disclosure of detailed information about financial instruments [Line Items]
Assets denominated in foreign currencies | $	$ 17,987,228				$ 15,034,220
Exchange rate	30.62	30.62	30.62	30.62
Currency Risk [member] | US$ [member]
Disclosure of detailed information about financial instruments [Line Items]
Assets denominated in foreign currencies	$ 4,600,745	$ 149,837			6,418,052	$ 208,989
Liabilities denominated in foreign currencies	$ 650,178	$ 21,175			$ 338,762	$ 11,031
Currency Risk [member] | US$ [member] | Financial Liability [member]
Disclosure of detailed information about financial instruments [Line Items]
Exchange rate | $ / $	30.705	30.705	30.705	30.705	30.71	30.71	30.71	30.71
Currency Risk [member] | US$ [member] | Financial Asset [member]
Disclosure of detailed information about financial instruments [Line Items]
Exchange rate | $ / $	30.705	30.705	30.705	30.705	30.71	30.71	30.71	30.71
Currency Risk [member] | JPY [member]
Disclosure of detailed information about financial instruments [Line Items]
Assets denominated in foreign currencies	$ 41,030		¥ 188,904		$ 26,712		¥ 114,940
Liabilities denominated in foreign currencies	$ 239,412		¥ 1,102,264		$ 368,989		¥ 1,587,732
Currency Risk [member] | JPY [member] | Financial Liability [member]
Disclosure of detailed information about financial instruments [Line Items]
Exchange rate	0.2172	0.2172	0.2172	0.2172	0.2324	0.2324	0.2324	0.2324
Currency Risk [member] | JPY [member] | Financial Asset [member]
Disclosure of detailed information about financial instruments [Line Items]
Exchange rate	0.2172	0.2172	0.2172	0.2172	0.2324	0.2324	0.2324	0.2324
Currency Risk [member] | RMB [member]
Disclosure of detailed information about financial instruments [Line Items]
Assets denominated in foreign currencies	$ 24,210			¥ 5,595	$ 31,733			¥ 7,199
Currency Risk [member] | RMB [member] | Financial Asset [member]
Disclosure of detailed information about financial instruments [Line Items]
Exchange rate	4.327	4.327	4.327	4.327	4.408	4.408	4.408	4.408
Other Risks [Member] | JPY [member]
Disclosure of detailed information about financial instruments [Line Items]
Assets denominated in foreign currencies	$ 120,317		¥ 553,946		$ 338,102		¥ 1,454,830
Other Risks [Member] | JPY [member] | Financial Asset [member]
Disclosure of detailed information about financial instruments [Line Items]
Exchange rate	0.2172	0.2172	0.2172	0.2172	0.2324	0.2324	0.2324	0.2324
Other Risks [Member] | RMB [member]
Disclosure of detailed information about financial instruments [Line Items]
Assets denominated in foreign currencies					$ 4,086,378			¥ 927,037
Other Risks [Member] | RMB [member] | Financial Asset [member]
Disclosure of detailed information about financial instruments [Line Items]
Exchange rate					4.408	4.408	4.408	4.408

Financial Risk Management and_5

Financial Risk Management and Fair Values of Financial Instruments - Additional Information (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disclosure of detailed information about financial instruments [Line Items]
Realized and unrealized gain and loss arising from significant foreign exchange variation	$ 78,170	$ 448,097	$ (89,152)
Adjustments to interest rate	1%	1%	1%
General increase or decrease of 100 basis points (1%) in interest rates [member]
Disclosure of detailed information about financial instruments [Line Items]
Estimated decrease or increase in the Group's profit and equity based on an increase or decrease in the interest rates	$ 149,723	$ 140,561	$ 102,489
Equity price risk [member]
Disclosure of detailed information about financial instruments [Line Items]
Estimated decrease or increase in the Group's profit and equity based on an increase or decrease in the interest rates	$ 427	$ 1,282	$ 3,600
Percentage of increase or decrease in price of equity securities	1%	1%	1%

Financial Risk Management and_6

Financial Risk Management and Fair Values of Financial Instruments - Details of Exposure to Currency Risk Arising from Recognized Monetary Assets or Liabilities Denominated in a Currency Other Than Functional Currency (Detail) - Currency Risk [member] - TWD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Financial assets, class [member] | US$ [member]
Disclosure of nature and extent of risks arising from financial instruments [Line Items]
Change in exchange rate	5%	5%	5%
Financial assets, class [member] | JPY [member]
Disclosure of nature and extent of risks arising from financial instruments [Line Items]
Change in exchange rate	5%	5%	5%
Financial assets, class [member] | RMB [member]
Disclosure of nature and extent of risks arising from financial instruments [Line Items]
Change in exchange rate	5%	5%	5%
Financial liabilities, class [member] | US$ [member]
Disclosure of nature and extent of risks arising from financial instruments [Line Items]
Change in exchange rate	5%	5%	5%
Financial liabilities, class [member] | JPY [member]
Disclosure of nature and extent of risks arising from financial instruments [Line Items]
Change in exchange rate	5%	5%	5%
Profit and Loss [member] | Financial assets, class [member] | US$ [member]
Disclosure of nature and extent of risks arising from financial instruments [Line Items]
Effect of change in exchange rate	$ 230,037	$ 320,903	$ 260,390
Profit and Loss [member] | Financial assets, class [member] | JPY [member]
Disclosure of nature and extent of risks arising from financial instruments [Line Items]
Effect of change in exchange rate	2,052	1,336	1,702
Profit and Loss [member] | Financial assets, class [member] | RMB [member]
Disclosure of nature and extent of risks arising from financial instruments [Line Items]
Effect of change in exchange rate	1,211	1,587	1,074
Profit and Loss [member] | Financial liabilities, class [member] | US$ [member]
Disclosure of nature and extent of risks arising from financial instruments [Line Items]
Effect of change in exchange rate	32,509	16,938	73,410
Profit and Loss [member] | Financial liabilities, class [member] | JPY [member]
Disclosure of nature and extent of risks arising from financial instruments [Line Items]
Effect of change in exchange rate	$ 11,971	$ 18,449	$ 13,103

Financial Risk Management and_7

Financial Risk Management and Fair Values of Financial Instruments - Summary of Loss Rate Methodology (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Contract assets [member]
Disclosure of detailed information about financial instruments [Line Items]
Expected loss rate	0.045%	0.06%
Total carrying amount	$ 384,057	$ 381,587
Loss allowance	$ (174)	$ (229)
Accounts receivable including related parties [member]
Disclosure of detailed information about financial instruments [Line Items]
Expected loss rate	0.045%	0.06%
Total carrying amount	$ 5,328,835	$ 4,384,232
Loss allowance	$ (2,454)	$ (2,669)
Other receivable including related parties [member]
Disclosure of detailed information about financial instruments [Line Items]
Expected loss rate	0.045%	0.06%
Total carrying amount	$ 44,589	$ 131,908
Loss allowance	$ (13)	$ (45)

Financial Risk Management and_8

Financial Risk Management and Fair Values of Financial Instruments - Summary of Movements in Relation to Loss Allowance for Contract Assets, Accounts Receivable and Other Receivables (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disclosure of detailed information about financial instruments [Line Items]
Financial assets beginning balance	$ 15,034,220
Financial assets ending balance	17,987,228	$ 15,034,220
Contract assets [member]
Disclosure of detailed information about financial instruments [Line Items]
Financial assets beginning balance	(229)	(120)	$ (117)
Provision for impairment loss		(109)	(3)
Reversal of impairment loss	55
Financial assets ending balance	(174)	(229)	(120)
Accounts receivable including related parties [member]
Disclosure of detailed information about financial instruments [Line Items]
Financial assets beginning balance	(2,669)	(1,910)	(1,620)
Provision for impairment loss		(759)	(290)
Reversal of impairment loss	215
Financial assets ending balance	(2,454)	(2,669)	(1,910)
Other receivable including related parties [member]
Disclosure of detailed information about financial instruments [Line Items]
Financial assets beginning balance	(45)	(16)	(10)
Provision for impairment loss		(29)	(6)
Reversal of impairment loss	32
Financial assets ending balance	$ (13)	$ (45)	$ (16)

Financial Risk Management and_9

Financial Risk Management and Fair Values of Financial Instruments - Maturity Profile of Non-derivative Financial Liabilities Based on Contracted Undiscounted Payments (Detail) - TWD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Long-term bank loans	$ 15,580,584	$ 14,643,068
Lease liabilities	1,257,694	1,118,787
Guarantee deposits	21,235	21,600
Total	16,859,513	15,783,455
Within 1 year [member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Long-term bank loans	2,469,744	1,699,165
Lease liabilities	267,759	174,460
Total	2,737,503	1,873,625
1 to 3 years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Long-term bank loans	7,506,844	5,675,288
Lease liabilities	250,104	182,767
Total	7,756,948	5,858,055
3 to 5 years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Long-term bank loans	4,273,199	5,354,335
Lease liabilities	57,856	57,057
Total	4,331,055	5,411,392
Over 5 years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Long-term bank loans	1,330,797	1,914,280
Lease liabilities	681,975	704,503
Guarantee deposits	21,235	21,600
Total	$ 2,034,007	$ 2,640,383

Financial Risk Management an_10

Financial Risk Management and Fair Values of Financial Instruments - Summary of Natures of Assets and Liabilities (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Disclosure of detailed information about financial instruments [Line Items]
Financial assets at fair value through profit or loss	$ 42,735	$ 128,224
Financial assets at fair value through other comprehensive income	120,317	338,102
Financial assets at fair value	163,052	466,326
Financial assets at fair value	17,987,228	15,034,220
Foreign unlisted stocks [member] | Recurring fair value measurement [member]
Disclosure of detailed information about financial instruments [Line Items]
Financial assets at fair value through other comprehensive income	120,317	338,102
Listed stocks [member] | Recurring fair value measurement [member]
Disclosure of detailed information about financial instruments [Line Items]
Financial assets at fair value through profit or loss	42,735	128,224
Level 1 [member]
Disclosure of detailed information about financial instruments [Line Items]
Financial assets at fair value	42,735	128,224
Level 1 [member] | Listed stocks [member] | Recurring fair value measurement [member]
Disclosure of detailed information about financial instruments [Line Items]
Financial assets at fair value through profit or loss	42,735	128,224
Level 3 [member]
Disclosure of detailed information about financial instruments [Line Items]
Financial assets at fair value	120,317	338,102
Level 3 [member] | Foreign unlisted stocks [member] | Recurring fair value measurement [member]
Disclosure of detailed information about financial instruments [Line Items]
Financial assets at fair value through other comprehensive income	$ 120,317	$ 338,102

Financial Risk Management an_11

Financial Risk Management and Fair Values of Financial Instruments - Summary of Movements of Level 3 (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Disclosure of detailed information about financial instruments [Line Items]
Gains or losses recognized in profit or loss Recorded as non-operating income (expenses)	$ (39,254)	$ (1,282)	$ 69,404	$ (15,262)
Gains or losses recognized in other comprehensive gains (losses) Recorded as unrealized gain (loss) on valuation of financial assets at fair value through other comprehensive income	(217,785)	$ (7,113)	(46,419)	122,514
Level 3 [member] | Debt instruments [member]
Disclosure of detailed information about financial instruments [Line Items]
Movement of financial instruments beginning balance	338,102		384,521
Movement of financial instruments ending balance			338,102	$ 384,521
Level 3 [member] | Equity instruments [member]
Disclosure of detailed information about financial instruments [Line Items]
Movement of financial instruments beginning balance	338,102
Gains or losses recognized in other comprehensive gains (losses) Recorded as unrealized gain (loss) on valuation of financial assets at fair value through other comprehensive income	(217,785)		(46,419)
Purchases	12,500
Reclassified as investments accounted for using equity method	(12,500)
Movement of financial instruments ending balance	$ 120,317		$ 338,102

Financial Risk Management an_12

Financial Risk Management and Fair Values of Financial Instruments - Summary of Qualitative Information and Sensitivity Analysis of Changes in Significant Unobservable Inputs Under Valuation Model Used in Level Fair Value Measurement (Detail) - TWD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Disclosure of significant unobservable inputs used in fair value measurement of equity [line items]
Fair value	$ 120,317,000	$ 338,102,000
Non derivative equity instruments [member] | Foreign unlisted stocks [member]
Disclosure of significant unobservable inputs used in fair value measurement of equity [line items]
Fair value	$ 120,317,000	$ 338,102,000
Valuation technique	Comparable companies	Comparable companies
Non derivative equity instruments [member] | Foreign unlisted stocks [member] | Price book value multiple [member]
Disclosure of significant unobservable inputs used in fair value measurement of equity [line items]
Range (weighted average method)	$ 1.64
Relationship of inputs to fair value	The higher the multiple, the higher the fair value
Non derivative equity instruments [member] | Foreign unlisted stocks [member] | Enter prise value EBITDA multiple [member]
Disclosure of significant unobservable inputs used in fair value measurement of equity [line items]
Range (weighted average method)	$ 8.23	$ 4.82
Relationship of inputs to fair value	The higher the multiple, the higher the fair value	The higher the multiple, the higher the fair value
Non derivative equity instruments [member] | Foreign unlisted stocks [member] | Discount for lack of marketability [member]
Disclosure of significant unobservable inputs used in fair value measurement of equity [line items]
Range (weigted average method)	15.70%	15.80%
Relationship of inputs to fair value	The higher the discount for lack of marketability, the lower the fair value	The higher the discount for lack of marketability, the lower the fair value

Financial Risk Management An_13

Financial Risk Management And Fair Values Of Financial Instruments - Summary of Effect of Profit or Loss or of Other Comprehensive Income from Financial Assets Categorized (Detail) - Financial instruments at fair value through other comprehensive income [member] - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Disclosure of significant unobservable inputs used in fair value measurement of equity [line items]
Favorable Changes	$ 2,231	$ 6,866
Unfavorable Changes In Fair Value	2,152	6,922
Discount for lack of marketability [member]
Disclosure of significant unobservable inputs used in fair value measurement of equity [line items]
Favorable Changes	1,453	3,990
Unfavorable Changes In Fair Value	1,413	4,039
Foreign unlisted stocks [member] | Price to book ratio multiple [member]
Disclosure of significant unobservable inputs used in fair value measurement of equity [line items]
Favorable Changes	30
Unfavorable Changes In Fair Value	30
Foreign unlisted stocks [member] | Enter prise value EBITDA multiple [member]
Disclosure of significant unobservable inputs used in fair value measurement of equity [line items]
Favorable Changes	748	2,876
Unfavorable Changes In Fair Value	$ 709	$ 2,883

Segment Information - Financial

Segment Information - Financial Segment Information for Operating Segments (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Revenue
Revenue	$ 21,356,228	$ 697,460	$ 23,517,064	$ 27,400,035
Operating profit (loss)	1,908,452	62,327	3,216,679	5,562,389
Depreciation expenses	(4,779,333)		(4,751,902)	(4,634,112)
Share of profit of associates	219,891	7,182	453,715	625,733
Interest income	193,189	$ 6,309	57,199	9,980
Interest expense	(265,957)		(142,439)	(120,998)
Purchase of property, plant and equipment	3,228,471		4,918,482	6,552,702
External [member]
Revenue
Revenue	21,356,228		23,517,064	27,400,035
Operating segments [member] | Testing [member]
Revenue
Revenue	4,394,726		5,243,997	5,899,600
Operating profit (loss)	514,707		1,253,477	1,814,021
Depreciation expenses	(1,065,689)		(1,042,455)	(921,999)
Purchase of property, plant and equipment	749,158		1,086,682	1,841,359
Operating segments [member] | Testing [member] | External [member]
Revenue
Revenue	4,394,726		5,243,997	5,899,600
Operating segments [member] | Assembly [member]
Revenue
Revenue	4,629,430		6,705,898	7,963,714
Operating profit (loss)	(1,180,481)		(93,585)	857,304
Depreciation expenses	(722,462)		(694,835)	(576,138)
Purchase of property, plant and equipment	568,289		957,790	1,553,475
Operating segments [member] | Assembly [member] | External [member]
Revenue
Revenue	4,629,430		6,705,898	7,963,714
Operating segments [member] | LCDD [member]
Revenue
Revenue	7,821,640		7,288,642	8,211,099
Operating profit (loss)	2,058,285		1,795,741	2,336,394
Depreciation expenses	(2,547,253)		(2,505,297)	(2,579,150)
Purchase of property, plant and equipment	1,756,590		2,677,489	2,748,697
Operating segments [member] | LCDD [member] | External [member]
Revenue
Revenue	7,821,640		7,288,642	8,211,099
Operating segments [member] | Bumping [member]
Revenue
Revenue	4,510,432		4,278,527	5,325,622
Operating profit (loss)	522,386		268,159	561,642
Depreciation expenses	(435,709)		(500,863)	(549,020)
Purchase of property, plant and equipment	152,908		196,521	408,751
Operating segments [member] | Bumping [member] | External [member]
Revenue
Revenue	4,510,432		4,278,527	5,325,622
Operating segments [member] | Others [member]
Revenue
Revenue	59,481		50,600	43,808
Operating profit (loss)	(6,194)		(6,821)	(6,987)
Depreciation expenses	(8,220)		(8,452)	(7,805)
Share of profit of associates	420,393		884,555	1,211,177
Interest income	193,189		57,199	9,980
Interest expense	(265,957)		(142,439)	(120,998)
Purchase of property, plant and equipment	1,526			420
Operating segments [member] | Others [member] | Intersegment [member]
Revenue
Revenue	59,481		50,600	43,808
Elimination [member]
Revenue
Revenue	(59,481)		(50,600)	(43,808)
Operating profit (loss)	(251)		(292)	15
Share of profit of associates	(200,502)		(430,840)	585,444
Elimination [member] | Intersegment [member]
Revenue
Revenue	$ (59,481)		$ (50,600)	$ (43,808)

Segment Information - Schedule

Segment Information - Schedule of Information on Products and Services (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Disclosure of products and services [line items]
Net revenue	$ 21,356,228	$ 697,460	$ 23,517,064	$ 27,400,035
Percentage of total revenue	100%	100%	100%	100%
Testing [member]
Disclosure of products and services [line items]
Net revenue	$ 4,394,726		$ 5,243,997	$ 5,899,600
Percentage of total revenue	20%	20%	22%	22%
Assembly [member]
Disclosure of products and services [line items]
Net revenue	$ 4,629,430		$ 6,705,898	$ 7,963,714
Percentage of total revenue	22%	22%	29%	29%
LCDD [member]
Disclosure of products and services [line items]
Net revenue	$ 7,821,640		$ 7,288,642	$ 8,211,099
Percentage of total revenue	37%	37%	31%	30%
Bumping [member]
Disclosure of products and services [line items]
Net revenue	$ 4,510,432		$ 4,278,527	$ 5,325,622
Percentage of total revenue	21%	21%	18%	19%

Segment Information - Geographi

Segment Information - Geographic Information of Revenue (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Disclosure of geographical areas [Line Items]
Revenue	$ 21,356,228	$ 697,460	$ 23,517,064	$ 27,400,035
ROC [member]
Disclosure of geographical areas [Line Items]
Revenue	17,287,574		18,671,142	21,608,567
Japan [member]
Disclosure of geographical areas [Line Items]
Revenue	1,176,163		1,989,805	1,768,460
People's Republic of China ("PRC") [member]
Disclosure of geographical areas [Line Items]
Revenue	1,729,908		1,970,943	1,899,362
Singapore [member]
Disclosure of geographical areas [Line Items]
Revenue	676,088		390,488	1,630,733
Others [member]
Disclosure of geographical areas [Line Items]
Revenue	$ 486,495		$ 494,686	$ 492,913

Segment Information - Schedul_2

Segment Information - Schedule of Geographical Information (Detail) - TWD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Non-current assets [abstract]
Total non-current assets	$ 20,367,567	$ 21,680,847
ROC [member]
Non-current assets [abstract]
Total non-current assets	20,360,166	21,677,980
PRC [member]
Non-current assets [abstract]
Total non-current assets	1,279	2,291
Others [Member]
Non-current assets [abstract]
Total non-current assets	$ 6,122	$ 576

Segment Information - Net Reven

Segment Information - Net Revenue from Customers Representing at Least 10% of Total Revenue (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Disclosure of major customers [Line Items]
Net revenue	$ 21,356,228	$ 697,460	$ 23,517,064	$ 27,400,035
Percentage of total revenue	100%	100%	100%	100%
Customer A [member]
Disclosure of major customers [Line Items]
Net revenue	$ 5,251,529		$ 4,705,064	$ 5,681,277
Percentage of total revenue	25%	25%	20%	21%
Customer B [Member]
Disclosure of major customers [Line Items]
Net revenue	$ 2,834,188		$ 1,868,583	$ 2,484,611
Percentage of total revenue	13%	13%	8%	9%
Customer M [Member]
Disclosure of major customers [Line Items]
Net revenue	$ 1,320,905		$ 2,278,645	$ 2,832,088
Percentage of total revenue	6%	6%	10%	10%

Financial Statements Schedule_3

Financial Statements Schedule: Valuation and Qualifying Accounts (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Allowance for Impairment of property, plant and equipment [member]
Disclosure of details of valuation and qualifying accounts [Line Items]
January 1	$ 194,467	$ 183,179	$ 182,002
Additions charged to expense or deduction of revenue	9,236	12,721	4,843
Deduction/Write-offs/Reversal		(1,433)	(3,666)
December 31	203,703	194,467	183,179
Allowance for Impairment of Obsolescence and Decline in Market Value of Inventories [Member]
Disclosure of details of valuation and qualifying accounts [Line Items]
January 1	105,630	121,586	79,815
Additions charged to expense or deduction of revenue	80,633		41,771
Deduction/Write-offs/Reversal		(15,956)
December 31	186,263	105,630	121,586
Provision for deficiency compensation [member]
Disclosure of details of valuation and qualifying accounts [Line Items]
January 1	26,643	4,281	3,463
Additions charged to expense or deduction of revenue	21,495	79,827	11,898
Deduction/Write-offs/Reversal	(14,574)	(57,465)	(11,080)
December 31	33,564	26,643	4,281
Sales for allowance [member]
Disclosure of details of valuation and qualifying accounts [Line Items]
January 1	37,123	9,849	9,864
Additions charged to expense or deduction of revenue	112,488	94,641	34,744
Deduction/Write-offs/Reversal	(111,944)	(67,367)	(34,759)
December 31	$ 37,667	$ 37,123	$ 9,849

Uncategorized Items - imos-2023

Label	Element	Value
Additional paid-in capital [member]
Additional paid-in capital	ifrs-full_AdditionalPaidinCapital	$ 6,055,773,000
Additional paid-in capital [member] | Others [Member]
Additional paid-in capital	ifrs-full_AdditionalPaidinCapital	12,290,000
Additional paid-in capital [member] | Share premium [member]
Additional paid-in capital	ifrs-full_AdditionalPaidinCapital	$ 6,043,483,000