US expat taxes in South Korea: the complete guide

The baseline: who must file and what they must file

US citizens and permanent residents living in South Korea must file a US federal income tax return (Form 1040) every year, reporting worldwide income. This obligation does not disappear because you are already a Korean tax resident and paying Korean income tax. The two systems run in parallel.

Beyond the income tax return, two reporting obligations apply to most Americans with Korean financial accounts:

• FBAR (FinCEN Form 114): Required when the aggregate balance of all foreign financial accounts exceeds $10,000 at any point during the calendar year. Covers Korean bank accounts (Kookmin, Shinhan, KEB Hana, Woori, IBK) and local brokerage accounts. Korea’s NPS balance is explicitly exempt.
• Form 8938 (FATCA): Filed as an attachment to Form 1040 when foreign financial assets exceed $200,000 at year-end or $300,000 at any time (single filer abroad); $400,000 / $600,000 for married filing jointly.

US expats receive an automatic two-month filing extension to June 15. A further extension to October 15 is available by filing Form 4868. Extensions cover the filing deadline only, tax owed is still due April 15.

South Korean income tax: rates, residency, and the local surtax

South Korea taxes residents on worldwide income. Tax residency is established by domicile in Korea or by being present for 183 or more days in a tax year (January 1 to December 31). Employment, business, interest, dividends, and rental income are all subject to Korean income tax.

Salaried employees settle through the Yeonmal Jeonsan (연말정산) year-end process each January. The NTS’s HomeTax (홈택스) platform at hometax.go.kr is where employees view their 근로소득원천징수영수증 (withholding receipt), the document that feeds the US Form 1116 Foreign Tax Credit calculation.

Class A vs. Class B income and the Foreigner Flat-Tax Election

Korean employment income falls into two categories with different withholding mechanics:

• Class A (근로소득 갑종): Paid by a Korean employer or a foreign company’s Korean affiliate. Korean income tax withheld monthly by the employer.
• Class B (근로소득 을종): Paid directly by a foreign company with no Korean affiliate. No monthly withholding; the employee files and pays Korean income tax annually (종합소득세 신고).

The 19% flat-tax election for foreign workers

Foreign workers who begin employment in South Korea on or before December 31, 2026 may elect a flat 19% Korean national income tax rate on Korean-source employment income, instead of standard national progressive rates of 6%–45%. The 10% local income surtax applies either way, so the comparison a worker is actually making is 20.9% against the combined bracket rates in the table above, which run from 6.6% to 49.5%. The election is generally advantageous for earners above approximately KRW 130 million annually.

Electing the flat rate forfeits all standard Korean deductions and credits. More importantly for US purposes: the flat rate reduces Korean taxes paid, directly reducing the Foreign Tax Credit available on the US return. Whether the flat rate is beneficial on a combined basis requires modeling both countries together before the election is made. For detailed threshold comparisons and payroll election procedures, see our in-depth guide on the South Korea 19% Flat Tax for Foreigners vs US Taxes.

Korean severance pay (toejikgeum / 퇴직금) and the US tax mismatch

Under the Korean Labor Standards Act, employees who have worked for an employer for one year or more are entitled to statutory severance pay (toejikgeum / 퇴직금) equal to at least 30 days’ average wages per year of service. Many employers fund this through the IRP (퇴직연금) system. The severance is paid in a lump sum when employment ends.

Korea classifies toejikgeum as 퇴직소득 (retirement income) and taxes it at highly favorable effective rates using an exemption formula tied to years of service, often resulting in a Korean effective rate in the single digits for moderate severance amounts.

The US does not respect Korea’s favorable treatment. For US purposes, severance pay is ordinary compensation income, fully includable in gross income in the year received. The Foreign Tax Credit for Korean tax paid can offset some US liability, but because Korea taxes severance at low effective rates, the credit is typically small. Americans leaving Korean employment after multiple years of service can face a meaningful unexpected US tax bill on severance that felt tax-free on the Korean side.

Before leaving: model the US tax impact before severance is paid; assess whether FEIE coverage is available (§911(b) can apply to severance qualifying as foreign earned income); and confirm the Foreign Tax Credit basket treatment of the Korean tax withheld. For a detailed breakdown of timing strategies and DC/IRP rollover traps, read our dedicated guide on Korean Severance Pay (Toejikgeum) and US Taxes.

National Pension Service (NPS / 국민연금): what’s reportable, what isn’t

Korea’s mandatory public pension, the National Pension Scheme (국민연금), requires employer and employee contributions of 4.5% each of the employee’s standard monthly income (capped at KRW 6,370,000/month for July 2025 to June 2026). The pension reform passed by Korea’s National Assembly on 20 March 2025 raises the combined rate from 9% to 13% in annual steps of 0.5 points, running from January 1, 2026 through 2033. The first step puts it at 9.5% for 2026, so 4.75% each side, and it rises again each January.

US tax treatment of NPS contributions

Employee NPS contributions are not excludable or deductible on the US return, paid from after-US-tax wages. Employer NPS contributions are a payroll tax on the employer and not included in the employee’s US gross income.

NPS reporting exemptions

The NPS balance is explicitly excluded from Form 8938 reporting (foreign government social security carve-out). The prevailing practitioner position is that it is also not reportable on the FBAR. The NPS does not trigger Form 3520 or Form 3520-A reporting.

Individual Retirement Pensions (IRP / 퇴직연금)

Private retirement accounts (including IRPs and Pension Savings accounts, 연금저축) are generally treated by US practitioners as foreign grantor trusts, triggering:

• Form 3520: Reports contributions and distributions during the year.
• Form 3520-A: Annual information return for the foreign grantor trust (frequently unavailable from Korean financial institutions).
• FBAR and Form 8938: Reports the aggregate account balances once reporting thresholds are crossed.

Eligible tax-favored foreign retirement trusts may be exempt from Forms 3520 and 3520-A under Rev. Proc. 2020-17. There is no IRS ruling classifying any specific Korean IRP as qualifying; the analysis is fact-specific. Investments held inside an IRP (Korean mutual funds, ETFs, variable insurance products) are almost always PFICs, adding Form 8621 obligations.

Korean ETFs and mutual funds: the PFIC problem

Any Korean-registered collective investment vehicle, KODEX ETFs, TIGER ETFs, ordinary Korean mutual funds (펜드 / 집합투자기구), equity-linked securities (ELS), K-REITs, is almost certainly a Passive Foreign Investment Company (PFIC) under US tax law. Under the default §1291 regime, gains on disposition and excess distributions are taxed as ordinary income, not at preferential long-term capital-gain rates, and carry an interest charge for each prior year’s deferral. Each PFIC requires a separate Form 8621. Failure to file keeps the statute of limitations open on the entire return.

The practical path for Americans in Korea: hold global equity exposure through US-domiciled ETFs (VTI, VXUS) via a US brokerage that accepts overseas addresses, Charles Schwab International and Interactive Brokers are the two that consistently work, rather than buying Korean-registered funds. Korean individual stocks listed on KOSPI or KOSDAQ are not PFICs. For an in-depth analysis of KODEX/TIGER reporting and Mark-to-Market elections, see our dedicated guide on Investing in Korea: ETFs, PFICs, and Expat Solutions.

The Jeonse (전세) system and US tax reporting

Jeonse is Korea’s distinctive key-money rental arrangement: the tenant pays the landlord a large lump-sum deposit (typically 50–80% of the property's market value) instead of monthly rent, for a lease of generally two years. The landlord holds the cash interest-free and returns the full principal at lease end.

• FBAR and Form 8938: If the Jeonse deposit is held in a bank account in the tenant’s name, that account is reportable at the usual thresholds. If paid directly to the landlord’s personal account with no tenant control, it is the landlord’s account and not reportable by the tenant.
• Section 988 currency gains and losses: when the KRW deposit is refunded and converted to USD, any gain from KRW appreciation is commonly reported as ordinary income under IRC §988, though §988(e)(1) excludes personal transactions from that section and some practitioners treat the gain as capital. A loss from KRW depreciation is generally a non-deductible personal loss under §165(c).
• No imputed rent: The IRS does not impute rental-equivalent income to the tenant on a standard residential Jeonse arrangement.

For full analysis on currency gains, FBAR filing, and claiming the Foreign Housing Exclusion on Korean leases, read our complete guide to South Korea Jeonse (전세) Deposits & US Expat Taxes.

The US-Korea tax treaty: what it actually does for US citizens

The US-South Korea income tax treaty has been in force since 1979. The savings clause in Article 4(4) preserves the US right to tax its citizens as though the treaty had never been signed. For US citizens in Korea, this eliminates most direct exemption benefits. What remains:

• Article 5 (Elimination of Double Taxation): Authorises the Foreign Tax Credit mechanism.
• Article 12 (Dividends): Reduces Korean withholding on dividends to 15% (10% for ≥10% corporate shareholders), vs. statutory 22%.
• Article 13 (Interest): Reduces Korean withholding on interest to 12%, vs. statutory 22%.
• Article 14 (Royalties): Reduces Korean withholding on royalties to 15% (10% for copyright/artistic royalties).
• Article 20 (Teachers and Researchers): Two-year exemption from Korean tax for qualifying American professors visiting Korea for teaching.
• Article 21 (Students): Exemption from Korean tax on qualifying scholarship and maintenance payments.
• Article 23 (Private Pensions and Annuities): Private pensions from Korean sources paid to US residents are in principle taxable only in the US; the savings clause modifies this for US citizens but the article shapes the FTC calculation for pension distributions.

The US-Korea Social Security Totalization Agreement

The US and Korea have had a Social Security Totalization Agreement in force since April 2001. Unlike Thailand and Singapore, Korea’s agreement prevents double social security taxation.

For salaried employees: American employees covered by Korea’s NPS are exempt from US Social Security (FICA) taxes on their Korean employment income.

For self-employed Americans (개인사업자): Self-employed Americans registered in Korea’s NPS are exempt from the 15.3% US self-employment tax on their Korean self-employment income, but only if a Certificate of Coverage is obtained from the Korean National Pension Service and attached to Form 1040. Without it, US self-employment tax applies on top of Korean NPS contributions.

Owning a Korean business: CFC, Form 5471, and GILTI

Americans who own a Korean corporation, a Jusik Hoesa (주식회사) or a Yuhan Hoesa (유한회사), face complex US reporting obligations unrelated to whether dividends are paid. A foreign corporation becomes a Controlled Foreign Corporation (CFC) when US shareholders who each own at least 10% together own more than 50% by vote or value. Form 5471 must be filed annually. Form 5471 also applies when acquiring a stake that reaches 10%, acquiring an additional 10% block, becoming a US person while already holding 10%, disposing of enough to fall below 10%, or controlling the company at any point during the year. There is no 30-day minimum holding period for the control test.

As a US shareholder of a CFC, a proportionate share of the company’s Subpart F income and net CFC tested income (formerly GILTI, renamed under the One Big Beautiful Bill Act for tax years beginning after 2025) may be includable in personal US income even if the company retains all profits and pays no dividends.

Korean real estate: rental income, capital gains, and the §121 exclusion

Korean rental income goes on Schedule E. Korean income tax paid on the rental is creditable on Form 1116. Depreciation on foreign residential rental property is calculated over a 30-year ADS period based on the property’s historical USD cost basis at the date of purchase exchange rate.

Selling a Korean property requires calculating the gain in USD on Form 8949 and Schedule D. The IRC §121 primary-residence exclusion, up to $250,000 (single) / $500,000 (joint return), applies to a principal residence abroad, subject to all four conditions: joint return; either spouse meets the ownership test; both spouses meet the two-of-five-year use test; neither spouse is ineligible under the one-qualifying-sale-every-two-years limit in §121(b)(3).

Korean capital-gains tax (양도소득세) paid on the disposal is creditable on Form 1116. If Korea exempts the sale or charges minimal tax, any US gain above the §121 exclusion is taxable without offset.

Never filed from Korea? How Streamlined catch-up works

Americans who have been living in Korea and have never filed US taxes have a structured path back through the Streamlined Filing Compliance Procedures, provided the non-filing was non-willful.

The relevant track is the Streamlined Foreign Offshore Procedures (SFOP):

• File 3 years of delinquent federal tax returns (Form 1040).
• File 6 years of delinquent FBARs (FinCEN Form 114).
• Submit a signed Form 14653 certifying non-willful conduct.
• 0% offshore penalty: No miscellaneous offshore penalty applies to the disclosed accounts.

Korea-resident Americans almost always meet the non-residency test: no US abode and physically outside the US for at least 330 full days in one or more of the three most recent tax years for which the return due date has passed. On a joint return, both spouses must independently meet the test.

2026 update: The IRS withdrew the Delinquent FBAR Submission Procedures on July 1, 2026. There is no longer a published, guaranteed penalty-free FBAR-only route. Late FBARs still go to FinCEN via BSA E-Filing with a reasonable-cause statement, but the outcome is discretionary under IRM 4.26.16.3.11. The SFOP remains the cleanest path for most Americans in Korea with unreported accounts.

Renouncing US citizenship in South Korea

Americans who have permanently settled in Korea, naturalized as Korean citizens, or decided to end their US tax obligation may consider renouncing US citizenship. The process must be completed in person at the US Embassy in Seoul (Gwanghwamun).

Effective April 13, 2026, the administrative fee for a Certificate of Loss of Nationality (CLN) was reduced from $2,350 to $450 (Fed. Reg. 2026-04931).

Renunciation triggers covered expatriate status, and potential mark-to-market exit tax under IRC §877A, if any of three tests are met:

1. Net worth exceeds $2,000,000 at the time of expatriation.
2. Average annual net income tax liability for the five preceding years exceeds $206,000 (2025) / $211,000 (2026).
3. Failure to certify five years of full US tax compliance on Form 8854.

Covered expatriates face a deemed mark-to-market sale of all worldwide assets the day before expatriation, with the first $890,000 (2025) / $910,000 (2026) of net unrealized gain excluded. Tax-deferred accounts, IRAs, 401(k)s, 529 plans, HSAs, are deemed distributed in full.

Four worked examples

The most common US tax mistakes Americans make in Korea

• Deducting NPS employee contributions on the US return. They are not deductible. Wages must be reported gross.
• Treating KODEX or TIGER ETFs like US ETFs. They are PFICs. Each requires Form 8621; failure to file extends the statute of limitations on the entire return.
• Assuming the tax treaty exempts Korean income. The savings clause in Article 4(4) prevents this.
• Electing the FEIE and losing the Additional Child Tax Credit. Electing the FEIE for any amount bars the refundable ACTC for the entire year under IRC §24(d)(3).
• Electing the 19% flat tax without modeling the US FTC impact. Lower Korean tax = lower FTC = higher US tax.
• Failing to obtain a Certificate of Coverage before filing as self-employed. Without it, US self-employment tax applies on top of Korean NPS contributions.
• Reporting IRP accounts on FBAR but missing Forms 3520 / 3520-A. Both obligations are required independently.
• Assuming severance is tax-free in the US because Korea taxed it lightly. Severance is ordinary US income regardless of Korean treatment.
• Missing the §988 currency gain on a Jeonse refund. KRW appreciation during the lease term produces taxable ordinary income on the US return.

South Korea expat tax: common questions

How to get help

Describe the situation: length of time in Korea, visa type (E-series, F-series, D-series, or Korean naturalization), employer type (chaebol, SME, foreign company, own business), any Korean brokerage or mutual-fund holdings, US filing history, and whether any Korean IRP or pension accounts are held. Capital Tax Limited responds within two business days with a scope, a fee range, and a recommendation on whether Streamlined or standard annual filing applies.

Get in touch