Do You Get Taxed Twice? How the Foreign Tax Credit Works
이중과세를 막는 외국납부세액공제 완전 해설 — 2026

Overview — No, You Don't Get Taxed Twice 아니요, 이중으로 과세되지 않습니다

When a person becomes a U.S. tax resident, the U.S. taxes all worldwide income — including Korean salary, rental income, business profits, and investment income. Korea simultaneously taxes Korean-source income under its own domestic law. This creates the appearance of double taxation. The Foreign Tax Credit (Form 1116) is the mechanism that prevents this: Korean income taxes paid can be credited dollar-for-dollar against the U.S. tax on the same income.

The FTC Limitation Formula — Exact Mechanics FTC 한도 공식 — 정확한 계산 구조

The FTC cannot exceed the U.S. tax attributable to the foreign-source income — this prevents foreign taxes from offsetting U.S. tax on U.S.-source income. The basic formula is correct in concept, but applying it correctly requires adjustments that are often omitted in simplified explanations.

• The credit allowed is the SMALLER of:(a) the actual Korean tax paid (converted to USD), or (b) the calculated limitation. If Korean tax paid is less than the limitation, the full Korean tax is creditable. If Korean tax paid exceeds the limitation, only the limitation amount is creditable in the current year — the excess becomes a carryover.
• Calculated separately for each basket: The limitation formula is applied independently to the general basket and the passive basket (and any other applicable basket). A taxpayer with both Korean salary (general) and Korean rental income (passive) computes two separate Form 1116 limitation calculations.
• "Worldwide income" includes ALL income, not just foreign: The denominator of the ratio is total taxable income from all sources — U.S. and foreign combined. A taxpayer with $80,000 U.S. salary and $40,000 Korean salary has $120,000 total taxable income; the Korean income represents 33% of the total, and the FTC limitation for the general basket is approximately 33% of the total U.S. tax liability (subject to further adjustments).

5 Income Baskets — Not 4 5개 소득 바스켓 — 4개가 아님

Form 1116 requires separate limitation calculations for distinct income categories ("baskets" or "separate limitation categories"). The credit cannot cross baskets — excess credit in one basket cannot offset insufficient credit in another. There are five categories relevant to individual taxpayers, not four.

High-Tax Kickout Rule 고율 외국세 재분류 규정

The high-tax kickout rule prevents taxpayers from claiming an excessive FTC when foreign tax rates are disproportionately higher than U.S. rates on the same passive income. This rule was not mentioned in the original document but is directly relevant to Korean passive income given Korea's relatively high withholding rates on certain income types.

• Effect of kickout: When triggered, the income and associated foreign tax move from the passive basket to the general basket. This can be advantageous (if there is excess limitation in the general basket) or disadvantageous (if it causes the credit to be further limited) depending on the taxpayer's overall basket positions.
• Why it matters for Korean taxpayers: Most routine Korean passive income (15.4% bank interest withholding, standard dividend withholding) does not approach the 250% threshold and is unaffected. The rule becomes relevant primarily for unusual situations — certain Korean withholding tax rates on specific transaction types, or where Korea applies higher rates to non-resident-adjacent situations.

$300/$600 De Minimis Election — Skip Form 1116 $300/$600 소액 면제 — Form 1116 생략 가능

For taxpayers with small amounts of foreign tax, IRC §904(j) provides an election to claim the FTC directly on Schedule 3 without filing the full Form 1116 — significantly simplifying the return for taxpayers with modest Korean passive income.

Carryback & Carryforward Mechanics 소급공제 및 이월공제 메커니즘

When Korean tax paid exceeds the FTC limitation for the current year, the excess is not lost — it can be carried back 1 year or forward up to 10 years (except for the GILTI basket, which permits no carryover at all).

• Carryback first, then carryforward: Taxpayers must generally apply excess FTC to the prior year first (via an amended return, Form 1040-X) before carrying forward. This can generate an immediate refund for the prior year if FTC was underutilized that year. The carryback is optional — the taxpayer may elect to forgo it and carry forward only.
• 10-year carryforward, then expiration: Unused FTC carryforwards expire after 10 years if not used. Track carryforwards by basket (general carryforwards stay in the general basket; passive stays in passive) and by origination year (FIFO — oldest credits used first).
• GILTI basket: no carryover at all. Unlike general and passive baskets, excess FTC in the GILTI basket cannot be carried back or forward — it is simply lost if not used in the year generated. This is a significant disadvantage for Korean business owners with CFC structures and underscores the importance of careful FTC planning for that basket specifically.
• Carryovers are extremely valuable for high-Korean-tax years: A year with unusually high Korean tax (e.g., a large 퇴직금 payment with significant Korean withholding) may generate excess FTC beyond the current year's limitation. That excess carries forward and can offset U.S. tax in future years when Korean income is lower or U.S. tax on Korean income is higher.

FTC Cannot Generate a Refund FTC는 환급을 발생시키지 않음

5 Fully Computed Korean Examples 실제 계산 사례 5개

Common Mistakes 자주 발생하는 오류

• 1 Mixing the general and passive baskets on a single Form 1116 calculation. Korean salary (general) and Korean rental income (passive) must be calculated on separate Form 1116 computations. Combining them into a single limitation calculation overstates or understates the allowable credit and is a frequent source of IRS adjustment.
• 2 Forgetting the LTCG/qualified dividend rate adjustment in the limitation formula. When foreign-source income includes capital gains or qualified dividends taxed at preferential rates, the foreign-source income used in the FTC limitation ratio must be adjusted downward per IRS worksheets — not used at face value. Skipping this adjustment overstates the foreign-source income proportion and can result in an excessive credit being claimed.
• 3 Using the $300/$600 de minimis election when general basket income is also present. The simplified election under §904(j) requires that ALL foreign tax be attributable to passive category income reported on a payee statement. A taxpayer with both Korean salary and Korean bank interest cannot use the simplified election for the interest alone while filing Form 1116 for the salary — if there is any general basket foreign tax, the full Form 1116 process applies to the return.
• 4 Not tracking FTC carryovers by basket and by year. Excess FTC carryforwards must be tracked separately for the general basket and the passive basket — they cannot be merged. They also expire after 10 years on a FIFO basis. Taxpayers who do not maintain a carryover schedule risk losing valuable credits that expire unused, or misapplying carryforwards to the wrong basket.
• 5 Assuming GILTI basket credits work the same as general/passive. Korean business owners who hold 10%+ ownership in a Korean corporation (CFC) may have GILTI income subject to its own FTC basket — which permits NO carryback or carryforward. Excess GILTI basket credits are simply lost if unused in the year generated, unlike general and passive basket excess which carries forward 10 years.
• 6 Expecting a refund when Korean tax exceeds U.S. tax on the same income. The FTC is non-refundable. If Korean tax paid is larger than the U.S. tax otherwise owed on the same foreign income, the credit reduces U.S. tax to $0 and the excess becomes a carryover — it does not generate a cash refund for the difference.
• 7 Crediting Korean social insurance premiums (건강보험, 국민연금) as if they were income taxes. Only legally imposed Korean income taxes (소득세, 지방소득세) are creditable on Form 1116. Korean national health insurance and national pension contributions are social insurance payments, not income taxes, and cannot be included in the FTC calculation.
• 8 Not considering the high-tax kickout rule when Korean withholding on passive income is unusually high. While most routine Korean passive income withholding (15.4% on bank interest) does not trigger the high-tax kickout (250% of the top U.S. rate, roughly 92.5%), unusual Korean withholding situations should be checked against this threshold. If triggered, the income and tax move from the passive basket to the general basket, changing the limitation calculation.

Hanmi CPA Insight