9.5 Corporate Minimum Tax & Foreign Tax Credits

Three tax concepts that should not be mixed

The regular federal C corporation income-tax rate is 21% of taxable income. The corporate alternative minimum tax (CAMT) is a separate minimum-tax system for applicable corporations, generally effective for tax years beginning after 2022. It uses a 15% rate applied to adjusted financial statement income (AFSI) with statutory modifications. The older corporate AMT generally ended for tax years beginning after 2017. An old study source describing a universal corporate 20% AMT is not the 2025 rule.

Most small operating corporations are outside the modern applicable-corporation threshold. Nevertheless, a Part 2 candidate should distinguish which tax base and credit a question supplies. Financial-statement profit, regular taxable income, and AFSI are not interchangeable. A lower regular tax caused by accelerated depreciation does not itself prove that a corporation owes CAMT.

Applicable corporation and tax base

The general statutory threshold considers whether average annual AFSI exceeds $1 billion over the applicable three-tax-year period. Special rules govern aggregation, short years, newly formed corporations, and foreign-parented multinational groups. A foreign-parented group can involve both a $1 billion group test and a separate $100 million test for relevant domestic corporations and included income. S corporations, regulated investment companies, and real estate investment trusts are excluded from applicable-corporation status under the statutory definition.

Form 4626 and the applicable guidance supply the detailed computation and any available simplified method for determining status. The $1 billion test is not a simple gross-receipts test and should not be substituted for the $31 million §448(c) test used elsewhere in 2025. Once a corporation becomes applicable, a subsequent lower-income year does not automatically erase its status; the statutory exit rules matter.

AFSI starts from financial-statement income and includes adjustments such as prescribed depreciation treatment, specified taxes, entity and group items, and allowed financial-statement NOLs. The tentative minimum tax reflects a 15% computation and the allowed CAMT foreign tax credit. Compare it with the regular-tax and other relevant amounts under Form 4626 to determine additional CAMT. A complete calculation cannot be inferred merely from a GAAP income statement's bottom line.

Credit for prior-year minimum tax

Minimum-tax payments can create a minimum tax credit for later years under §53. Form 8827 tracks the credit and its allowed use. A carryforward is not an automatic cash refund and cannot be used without the current-year limitation. The basic idea is to allow qualifying prior minimum tax to offset regular tax when regular tax later exceeds the applicable tentative minimum-tax amount, using the form's exact adjustments.

Simplified illustration: Suppose the facts explicitly provide an available prior-year credit of $40,000 and current-year capacity of $15,000 under Form 8827, with no other relevant adjustments. The allowed credit is $15,000 and $25,000 remains. Do not deduct the credit from taxable income, apply a second 21% multiplier, or assume all $40,000 is refundable. The supplied capacity, rather than the carryforward balance alone, limits use.

Foreign taxes: deduction or credit

A corporation can generally elect a foreign income-tax credit for qualifying foreign taxes, rather than deducting the same tax. The foreign tax credit reduces federal tax dollar for dollar within its statutory limitation. A deduction instead reduces taxable income and therefore has a different effect. The same tax cannot supply both benefits.

Form 1118 generally handles corporate foreign tax credits. Separate categories of foreign income and sourcing rules matter. A simplified limitation is the relevant U.S. tax multiplied by the ratio of foreign-source taxable income in a category to worldwide taxable income, subject to the detailed statute. This prevents foreign taxes from freely eliminating U.S. tax on unrelated U.S.-source income.

Assume a question supplies a $12,000 foreign tax payment and a computed $9,000 credit limit for that category. The current allowed credit is generally $9,000, not the full payment. General foreign-tax-credit carryback and carryforward rules are commonly one year back and ten years forward, but special categories, including certain §951A items, have different rules. Read the category before assigning a carryover period.

Keep the forms and bases separate

A foreign tax credit is not simply another Form 3800 research or employment credit. A CAMT foreign tax credit is also a separate computation from the regular corporate foreign tax credit. Preserve carryforward schedules by tax type and category rather than combining every unused credit into one balance.

Official references

2025 Form 4626 instructions, Form 8827, and Form 1118 instructions, checked October 17, 2026. Use statutory rules effective for the tested year and applicable guidance; do not treat proposed rules as enacted law.