How Inheritance from Korea Is Taxed in the U.S.
한국 상속의 미국 세금 처리 — Form 3520 합산 규정과 패널티 구조 2026
The inheritance itself is tax-free, but Form 3520's related-party aggregation rule, the 5%-per-month penalty structure, and step-up basis mechanics require precise handling.
Overview — Tax-Free Receipt, Mandatory Reporting 상속 자체는 비과세, 신고는 의무
A U.S. person who inherits Korean real estate, cash, stocks, business interests, or pension rights owes no U.S. income tax on the inheritance itself — this is the foundational rule. But "no tax" does not mean "no paperwork." Large inheritances trigger Form 3520 reporting, inherited foreign accounts trigger FBAR/FATCA, and income generated by the inherited assets after the date of death is fully taxable going forward.
Form 3520 — The $100,000 Threshold and Aggregation Form 3520 — $100,000 기준과 합산 규정
A U.S. person must file Form 3520 (Part IV) if they receive more than $100,000 in aggregate from a nonresident alien individual or foreign estate (including related foreign persons) during the tax year. This $100,000 threshold is a fixed statutory amount — unlike many other thresholds in the tax code, it is not adjusted for inflation.
Result: Form 3520 filing required — $110,000 exceeds the $100,000 threshold, even though no single gift did.
| Source | 2026 Threshold | Inflation-Adjusted? |
|---|---|---|
| Foreign individuals / foreign estates (gifts and bequests) | $100,000 aggregate | NO — fixed by statute since enactment |
| Foreign corporations / foreign partnerships | $20,573 (2026) | YES — adjusted annually |
| Distributions from a foreign trust | Any amount — no minimum | N/A |
If the aggregate from individuals/estates exceeds $100,000, each individual gift over $5,000 must be separately identified by donor on the form.
Penalty Mechanics — 5% Per Month, Capped at 25% 패널티 구조 — 매월 5%, 최대 25%
The penalty for failing to timely or accurately file Form 3520 Part IV is not a flat 25% — it accrues monthly and is capped at that level.
- 5% of the unreported amount for each month the failure continues, up to a maximum of 25% — reached at month 5 and capped there regardless of how much longer the failure continues.
- Reasonable cause exception exists under IRC §6039F(c)(2) — but the standard is demanding, generally requiring circumstances beyond the taxpayer's control despite exercising ordinary business care. Relying on tax software that didn't flag the requirement has succeeded as a reasonable cause argument in at least one reported case, but is not a guaranteed defense.
- The penalty applies to the full inherited amount, not just any portion brought into the U.S. — inheriting $700,000 and transferring only $80,000 to a U.S. account still means the penalty exposure (if unreported) is calculated on the full $700,000.
Form 3520's Independent Filing Deadline Form 3520의 독립적인 마감일
Step-Up Basis on Inherited Korean Assets 상속받은 한국 자산의 기준가액 조정(Step-Up)
- U.S. tax basis in inherited assets becomes the fair market value (FMV) on the date of death(or alternate valuation date in limited estate circumstances) — converted to USD using the exchange rate on that date.
- This replaces the deceased's original purchase price entirely — pre-death appreciation is never taxed by the U.S. (it wasn't the heir's gain, and the U.S. doesn't tax the foreign decedent's estate — Section 9).
- Applies to Korean real estate, Korean stocks, and Korean business interests — a significant benefit that substantially reduces the eventual U.S. capital gain when the heir sells.
- Obtaining a reliable date-of-death valuation is essential — for real estate, a contemporaneous appraisal or comparable Korean market data; for closely-held business interests, a qualified business valuation. Documenting this at the time of inheritance, rather than reconstructing it years later at sale, is critical.
Income Generated After Inheritance 상속 이후 발생하는 소득
| Income Source | U.S. Form | FTC Available? |
|---|---|---|
| Rent from inherited Korean real estate | Schedule E (U.S. depreciation on the stepped-up basis) | YES — passive basket, for Korean income tax actually paid |
| Dividends from inherited Korean stocks | Schedule B | YES — passive basket, for Korean withholding |
| Interest from inherited Korean bank accounts | Schedule B | YES — passive basket, for Korean withholding |
| Capital gains when inherited assets are later sold | Schedule D, using the stepped-up basis | Depends — listed stock gains often have no Korean tax to credit (소액주주 exemption); real estate 양도세 generally is creditable |
Reporting by Asset Type 자산 유형별 신고 의무
- Korean bank accounts: FBAR if aggregate foreign accounts exceed $10,000; FATCA (Form 8938) if assets exceed the applicable threshold.
- Korean stocks (individual): dividends and eventual sale gains reportable; the holding account itself subject to FBAR/FATCA.
- Korean ETFs/mutual funds: inherited PFIC status carries forward — Form 8621 required annually, with the stepped-up basis as the new starting point for PFIC calculations (the punitive excess distribution regime can still apply to post-inheritance gains if no QEF/MTM election is timely made).
- Korean corporation shares: if the inherited stake is 10%+ of a Korean corporation, Form 5471 is required; if the corporation is a CFC, GILTI/NCTI analysis applies to the heir going forward.
- Korean real estate: if rented, Schedule E reporting begins using the stepped-up basis for depreciation.
Inherited Korean Pension Rights — 국민연금 상속받은 한국 연금 권리 — 국민연금
Why No U.S. Estate Tax on the Korean Decedent 한국 망인에게 미국 상속세가 적용되지 않는 이유
- U.S. estate tax applies only to U.S. citizens and U.S. domiciliaries — a Korean parent who was never a U.S. citizen and never domiciled in the U.S. is entirely outside the U.S. estate tax system, regardless of the size of their estate or what assets they held.
- Korea's own inheritance tax (상속세) applies instead, at progressive rates up to 50% (with a surtax pushing the effective top rate higher for certain large estates involving controlling shareholders).
- This is a one-way asymmetry worth understanding clearly: the heir (a U.S. person) faces no U.S. estate tax on this inheritance, but does face the Form 3520 reporting obligation and the ongoing income tax consequences on the inherited assets described throughout this guide.
5 Fully Computed Examples 실제 계산 사례 5개
Value at death: KRW 800,000,000 (rate at death: 1,300). Korean inheritance tax paid by the estate. Later sold for KRW 900,000,000 (rate at sale: 1,370). Korean 양도소득세 on the sale: KRW 5,000,000.
| U.S. basis (FMV at death): 800,000,000 ÷ 1,300 | $615,385 |
| Sale proceeds: 900,000,000 ÷ 1,370 | $656,934 |
| U.S. capital gain (only post-inheritance appreciation) | $41,549 — NOT the full KRW 800M-to-900M gain; the inheritance reset the basis |
| Korean inheritance tax (paid by the estate before distribution): NOT creditable against U.S. income tax — it's a transfer tax, not an income tax | No FTC for this |
| Korean 양도소득세 on the sale: 5,000,000 ÷ 1,370 = $3,650 — creditable, passive basket | Offsets U.S. capital gains tax on the $41,549 gain |
| Inherits KRW 90,000,000 (≈$66,000) from grandmother's estate, and separately KRW 70,000,000 (≈$51,000) from grandfather's estate, same year | Combined: ≈$117,000 — both decedents related |
| Aggregate exceeds $100,000 → Form 3520 required | Even though neither individual inheritance alone exceeded $100,000 |
| Korean bank account receiving the funds: must also be reported on FBAR (if >$10,000) and FATCA | Separate from the Form 3520 requirement |
Inherited $300,000 from a Korean parent's estate. Form 3520 was not filed; the omission is discovered and corrected 7 months after the original due date.
| 5% per month for the first 5 months (reaching the cap) | 25% × $300,000 = $75,000 maximum penalty |
| Months 6 and 7: no additional penalty (already capped at 25%) | Penalty remains $75,000, not higher |
| Reasonable cause defense, if successfully established | Could reduce or eliminate the penalty — burden of proof on the taxpayer |
| Inherits 100% of a Korean 주식회사 from a parent | No U.S. tax on the inheritance itself; basis steps up to date-of-death FMV (often requiring a business valuation) |
| Form 5471 required starting the year of inheritance — 100% ownership immediately makes the corporation a CFC | GILTI/NCTI inclusion begins on the corporation's tested income going forward, regardless of distributions |
| Check-the-box election (if the entity type qualifies) could convert to disregarded status | Would replace Form 5471/GILTI exposure with the simpler Form 8858 regime |
| Inherits a continuing 국민연금 survivor pension, KRW 12,000,000/year, post-2002 contribution-derived | Korea taxes this as 연금소득; Korean tax withheld per the pension statement (e.g., KRW 500,000) |
| U.S.: report as worldwide income (characterization analysis needed — potentially treaty-protected as a public pension, or standard FTC reporting) | $8,759 (12M ÷ 1,370) reportable, subject to further analysis |
| Korean tax withheld: potentially creditable — check the actual statement, don't assume $0 | 500,000 ÷ 1,370 = $365 potential FTC |
Common Mistakes 자주 발생하는 오류
- 1 Thinking inheritance below $100,000 from each parent separately means no Form 3520 is needed. The aggregation rule combines amounts from related foreign persons — two parents' separate gifts/bequests in the same year are added together against the single $100,000 threshold.
- 2 Treating the Form 3520 penalty as a flat 25% regardless of how late the filing is. It accrues at 5% per month, reaching the 25% cap at month 5 — earlier correction meaningfully reduces exposure.
- 3 Assuming Form 3520's deadline always exactly mirrors the income tax return's deadline. While the standard automatic extension does extend both, a discretionary additional extension for the income tax return does not automatically extend Form 3520 — creating a possible mismatch.
- 4 Using the deceased's original purchase price as basis instead of the stepped-up FMV at death. This understates the basis and overstates the eventual U.S. capital gain when the inherited asset is sold.
- 5 Assuming 국민연금 distributions are never subject to Korean tax, so no FTC is ever available. Post-2002 contribution-derived benefits are taxed by Korea — check the actual pension statement before concluding no credit exists.
- 6 Not filing Form 5471 immediately upon inheriting 10%+ of a Korean corporation. There is no grace period — the filing requirement (and GILTI/NCTI exposure if the corporation is a CFC) begins the year of inheritance.
- 7 Not obtaining a contemporaneous date-of-death valuation for inherited real estate or business interests. Reconstructing this years later, at the time of eventual sale, is far less reliable and harder to defend than documenting it at the time of inheritance.
- 8 Crediting Korean inheritance tax against U.S. income tax. Korean inheritance tax (상속세) is a transfer tax, not an income tax — it is never creditable via Form 1116 against any U.S. income tax, including future capital gains tax on the inherited asset.
Hanmi CPA Insight
The aggregation rule is the single most consequential mechanical detail in Form 3520 compliance, precisely because it catches situations that feel intuitively safe. A Korean-American who receives $60,000 from one parent and $50,000 from another in the same year may reasonably believe neither amount triggers anything — each is comfortably under $100,000. But the rule combines related-party transfers, and the $110,000 aggregate does trigger the filing requirement. This is exactly the kind of detail that a family distributing an estate across multiple gifts, or across multiple years from the same relatives, should have reviewed by a CPA before assuming any individual transfer is "too small to matter."
The penalty's monthly accrual structure matters practically because it means speed of correction has real value even after a deadline is missed. A taxpayer who discovers a missed Form 3520 one month late faces a different exposure than one who discovers it after a year — the penalty caps at 25% regardless, but correcting promptly within that window, combined with a genuine reasonable cause argument, is a meaningfully better position than waiting. Given that the underlying tax owed on a foreign inheritance is typically zero, the entire penalty exposure here is a pure compliance-failure cost — making prompt voluntary correction one of the highest-value actions available once a missed filing is discovered.
The 국민연금 question recurs across nearly every guide in this series for a reason: the default assumption that "Korea doesn't tax this pension" is wrong often enough, and consequential enough when wrong, that it deserves to be checked rather than assumed every single time it appears — including in the inheritance context, where a survivor benefit or continuing pension right passes to an heir along with the rest of the estate. The actual Korean pension statement, not a general rule of thumb, is what should drive the FTC determination.