Contents of Significant Accounts - Reconciliation Between Income Tax Expense and Income Before Tax At UMC's Applicable Tax Rate (Detail) $ in Thousands, $ in Thousands |
12 Months Ended | |||
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Dec. 31, 2025
TWD ($)
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Dec. 31, 2025
USD ($)
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Dec. 31, 2024
TWD ($)
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Dec. 31, 2023
TWD ($)
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| Reconciliation of accounting profit multiplied by applicable tax rates [abstract] | ||||
| Income before tax | $ 48,081,667 | $ 1,532,728 | $ 57,044,820 | $ 68,450,404 |
| At UMC's statutory income tax rate | 9,616,333 | 11,408,964 | 13,690,081 | |
| Adjustments in respect of current income tax of prior periods | 183,830 | (124,430) | (217,891) | |
| Net changes in loss carry-forward and investment tax credits | (5,737,173) | (2,026,085) | (2,179,234) | |
| Adjustment of deferred tax assets/liabilities for write-downs/reversals and different jurisdictional tax rates | (3,354,038) | 559,386 | 211,639 | |
| Tax effect of non-taxable income and non-deductible expenses: | ||||
| Tax exempt income | (617,013) | (472,756) | (1,428,035) | |
| Investment loss (gain) | 6,941,947 | 205,207 | (755,800) | |
| Dividend income | (224,961) | (231,267) | (323,182) | |
| Others | (32,566) | (610,092) | (145,520) | |
| Basic tax | 12,095 | 13,414 | 43,506 | |
| Estimated income tax on unappropriated earnings | (210,104) | (743,264) | (1,160,324) | |
| Deferred income tax related to changes in tax rates | (15,461) | 68 | 0 | |
| Effect of different tax rates applicable to UMC and its subsidiaries | 896,819 | 15,673 | 234,510 | |
| Taxes withheld in other jurisdictions | 105,847 | 44,489 | 38,346 | |
| Others | 337,299 | 330,887 | 303,174 | |
| Income tax expense recorded in profit or loss | $ 7,902,854 | $ 251,924 | $ 8,370,194 | $ 8,311,270 |
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- References Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- References Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- References Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition The amount that represents the difference between the tax expense (income) and the product of the accounting profit multiplied by the applicable tax rate(s) that the entity does not separately disclose in the same statement or note. [Refer: Accounting profit; Applicable tax rate] Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- References Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- References No definition available.
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- Definition The amount that represents the difference between the tax expense (income) and the product of the accounting profit multiplied by the applicable tax rate(s) that relates to foreign tax rates. [Refer: Accounting profit] Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition The product of the accounting profit multiplied by the applicable tax rate(s). [Refer: Accounting profit; Applicable tax rate] Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Adjustments for deferred tax assets and liabilities for writedowns reversal and different jurisdictional tax rates. No definition available.
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- Definition Current tax expense (income) on unappropriated retained earnings. No definition available.
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- Definition Income tax expense - basic tax. No definition available.
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- Definition Net change in loss carry forward and investment tax credits. No definition available.
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- Definition Tax effect of different tax rates applicable to subsidiaries. No definition available.
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- Definition Tax effect of non taxable income and non deductible expenses. No definition available.
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- Definition Tax effect of non taxable income and non deductible expenses - dividend income. No definition available.
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- Definition Tax effect of non taxable income and non deductible expenses - investment loss (gain). No definition available.
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- Definition Tax effect of non taxable income and non deductible expenses - others. No definition available.
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- Definition Tax effect of non taxable income and non deductible expenses - tax exempt income. No definition available.
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