Significant Related Party Transactions (Tables)

12 Months Ended

Dec. 31, 2025

Disclosure of transactions between related parties [line items]

Key management personnel compensation


	For the years ended December 31,
	2023		2024		2025
	NT$		NT$		NT$
	(In Thousands)		(In Thousands)		(In Thousands)
Short-term employee benefits	$	1,462,964	$	1,223,667	$	920,442
Post-employment benefits		2,732		2,603		2,358
Share-based payment		500,391		298,500		175,072
Others		618		417		351

Total	$	1,966,705	$	1,525,187	$	1,098,223

Subsidiaries [member]

Disclosure of transactions between related parties [line items]

Significant Transactions Between the Company and Related Parties

Significant intercompany transactions between consolidated entities were as follows:

For the year ended December 31, 2023


Entity	Counterparty	Transactions (Note A)
		Account	Amount			Terms (Note B)
		Account	Amount			Terms (Note B)
			NT$
			(In Thousands)
UMC	UMC-USA	Sales	$	61,923,652		Net 60 days
UMC	UMC-USA	Accounts receivable		5,827,800		—
UMC	USCXM	Sales		1,127,275 (Note C	)	Net 30 days
UMC	USCXM	Accounts receivable		11,688		—
UMC	UDS	Sales		364,948		Net 30 days
UMC	UDS	Accounts receivable		10,800		—
USJC	UMC-USA	Sales		3,487,292		Net 60 days
USJC	UMC-USA	Accounts receivable		342,835		—
USCXM	UMC-USA	Sales		1,208,630		Net 60 days
USCXM	UMC-USA	Accounts receivable		17,816		—
USCXM	UMC	Sales		134,303		Net 30 days - Net 45 days
USCXM	UDS	Sales		286,087		Month-end 30 days
USCXM	UDS	Accounts receivable		362		—
WAVETEK	UMC-USA	Sales		505,806		Net 60 days
WAVETEK	UMC-USA	Accounts receivable		53,916		—
HEJIAN	UMC-USA	Sales		384,067		Net 60 days
HEJIAN	UMC-USA	Accounts receivable		43,863		—
HEJIAN	UDS	Sales		159,523		Month-end 30 days
HEJIAN	UDS	Accounts receivable		2,696		—

For the year ended December 31, 2024


Entity	Counterparty	Transactions (Note A)
		Account	Amount			Terms (Note B)
		Account	Amount			Terms (Note B)
			NT$
			(In Thousands)
UMC	UMC-USA	Sales	$	58,145,772		Net 60 days
UMC	UMC-USA	Accounts receivable		6,970,670		—
UMC	USCXM	Sales		1,210,478 (Note C	)	Net 30 days
UMC	USCXM	Accounts receivable		12,623		—
UMC	UDS	Sales		337,007 (Note D	)	Net 30 days
USJC	UMC-USA	Sales		4,755,322		Net 60 days
USJC	UMC-USA	Accounts receivable		713,962		—
USCXM	UMC-USA	Sales		639,413		Net 60 days
USCXM	UMC-USA	Accounts receivable		137,666		—
USCXM	UDS	Sales		287,522 (Note D	)	Month-end 30 days
WAVETEK	UMC-USA	Sales		397,260		Net 60 days
WAVETEK	UMC-USA	Accounts receivable		39,086		—
HEJIAN	UMC-USA	Sales		240,749		Net 60 days
HEJIAN	UMC-USA	Accounts receivable		31,132		—

For the year ended December 31, 2025


Entity	Counterparty	Transactions (Note A)
		Account	Amount			Terms (Note B)
		Account	Amount			Terms (Note B)
			NT$
			(In Thousands)
UMC	UMC-USA	Sales	$	52,901,807		Net 60 days
UMC	UMC-USA	Accounts receivable		5,567,464		—
UMC	USCXM	Sales		1,157,346 (Note C	)	Net 30 days
UMC	USCXM	Accounts receivable		5,016		—
USJC	UMC-USA	Sales		5,263,816		Net 60 days
USJC	UMC-USA	Accounts receivable		959,612		—
USCXM	UMC-USA	Sales		423,720		Net 60 days
USCXM	UMC-USA	Accounts receivable		68,434		—
WAVETEK	UMC-USA	Sales		375,894		Net 60 days
WAVETEK	UMC-USA	Accounts receivable		79,412		—

Note A:

The significant intercompany transactions listed above include downstream and upstream transactions.

Note B:

The sales price to the above related parties was determined through mutual agreement in reference to market conditions.

Note C:

UMC authorized technology licenses to its subsidiary, USCXM, in the amount of US$0.35 billion, which was recognized as deferred revenue to be realized over time.

Note D:

In August 2024, HEJIAN has disposed of its 100% of ownership interest in the subsidiary, UDS.

Other related parties [member]

Disclosure of transactions between related parties [line items]

Significant Transactions Between the Company and Related Parties

Significant transactions between the Company and other related parties were as follows:

(i)

Name and Relationship of Related Parties


		Name of related parties		Relationship with the Company
		FARADAY TECHNOLOGY CORP. and its Subsidiaries		Associate
		UNIMICRON TECHNOLOGY CORP. and its Subsidiaries		Associate
		SILICON INTEGRATED SYSTEMS CORP. and its Subsidiaries		Associate (Note A)
		YANN YUAN INVESTMENT CO., LTD.		Associate
		PURIUMFIL INC.		Associate (Note B)
		TRANSLINK CAPITAL PARTNERS I, L.P.		Associate
		PHOTRONICS DNP MASK CORPORATION		Other related party
		XIAMEN JINYUAN INDUSTRIAL DEVELOPMENT CO., LTD.		Directors and supervisors of subsidiary (Note C)
		FUJIAN ELECTRONICS & INFORMATION INDUSTRY ENTREPRENEURSHIP INVESTMENT LIMITED PARTNERSHIP		Directors of subsidiary (Note C)

Note A: Prior to August 2023, SIS held one board seat on UMC’s Board of Directors. Therefore, SIS was classified as other related party. Beginning from August 2023, the Company determines that it has significant influence over SIS and accounts for its investment in SIS as an associate. Please refer to Note 6(7) for the relevant information.

Note B: In August 2025, the Board of Directors of the Company’s subsidiary, TERA ENERGY, resolved to merge with PURIUMFIL INC., with TERA ENERGY as the surviving company. The effective date of merger is October 3, 2025.

Note C: Beginning from July 2023, the company is no longer serving as the directors and supervisors of subsidiary, and therefore is no longer considered a related party to the Company.

(ii)

Operating revenues


	For the years ended December 31,
	2023		2024		2025
	NT$		NT$		NT$
	(In Thousands)		(In Thousands)		(In Thousands)
Associates	$	3,018,171	$	3,611,015	$	4,386,941
Other related party		4,463		—		—

Total	$	3,022,634	$	3,611,015	$	4,386,941

(iii)

Accounts receivable, net


	As of December 31,
	2024		2025
	NT$		NT$
	(In Thousands)		(In Thousands)
Associates
FARADAY TECHNOLOGY CORP. and its Subsidiaries
FARADAY TECHNOLOGY CORP.	$	456,332	$	336,736
ARTERY TECHNOLOGY CORPORATION, LTD.		148,508		76,840
Others		493		15,943
Other associates		14,680		72,630

Total	$	620,013	$	502,149

The sales price to the above related parties was determined through mutual agreement in reference to market conditions. The collection periods for domestic sales to related parties were

month-end

days, while the collection periods for overseas sales were

month-end

days or net 30 - 60 days.

(iv)

Significant asset transactions

Acquisition of subsidiaries’ ownership

For the year ended December 31, 2023:


	Trading Capital Amount		Transaction underlying		Purchase price
	RMB¥				NT$
	(In Thousands)				(In Thousands)
XIAMEN JINYUAN INDUSTRIAL DEVELOPMENT CO., LTD.		3,741,862		Ownership of USCXM	$	17,945,970
FUJIAN ELECTRONICS & INFORMATION INDUSTRY ENTREPRENEURSHIP INVESTMENT LIMITED PARTNERSHIP		674,762		Ownership of USCXM		3,263,473

Total		4,416,624			$	21,209,443

For the years ended December 31, 2024 and 2025: None.

Acquisition of investments accounted for under the equity method

For the year ended December 31, 2023:


	Trading Volume (In thousands of shares)		Transaction underlying	Purchase price
				NT$
				(In Thousands)
Associates		4,945	Stock of UNIMICRON	$	608,224

For the year ended December 31, 2024:


	Trading Volume (In thousands of shares)		Transaction underlying	Purchase price
				NT$
				(In Thousands)
Associates		1,723	Stock of FARADAY	$	533,973

For the year ended December 31, 2025: None.

Please refer to Note 6(7) for the relevant information.

Acquisition of intangible assets


	Purchase price
	For the years ended December 31,
	2023		2024		2025
	NT$		NT$		NT$
	(In Thousands)		(In Thousands)		(In Thousands)
FARADAY TECHNOLOGY CORP.	$	323,551	$	310,460	$	306,819

Disposal of subsidiary ownership

For the years ended December 31, 2023 and 2025: None.

For the year ended December 31, 2024:

Transaction
underlying

Trading Capital
Amount

Disposal price

Gain on
disposal

RMB¥

(In Thousands)

NT$

(In Thousands)

NT$

(In Thousands)

Associates

Subsidiary of SIS - SIS SEMICONDUCTOR (SHANDONG) CO., LTD.

Ownership
of UDS

30,000

341,387

352

On April 2, 2024, the Board of Directors of HEJIAN approved to dispose of its 100% of ownership interest in the subsidiary, UDS. The disposal was completed in August 2024.

(v)

Others

Mask expenditure


	For the years ended December 31,
	2023		2024		2025
	NT$		NT$		NT$
	(In Thousands)		(In Thousands)		(In Thousands)
Other related party	$	2,375,225	$	2,285,797	$	2,377,931

Other payables of mask expenditure


	As of December 31,
	2024		2025
	NT$		NT$
	(In Thousands)		(In Thousands)
Other related party	$	621,737	$	780,692

Cash dividends from Investee companies


	For the years ended December 31,
	2023		2024		2025
	NT$		NT$		NT$
	(In Thousands)		(In Thousands)		(In Thousands)
Investments accounted for under the equity method
Associates	$	1,870,372	$	1,070,614	$	592,309
Financial Assets at Fair Value through Other Comprehensive Income
Subsidiary of UNIMICRON - Unimicron Holding Limited		—		—		1,231,242

Total	$	1,870,372	$	1,070,614	$	1,823,551