U.S. Taxes for Americans Living in South Korea: The 2026 Guide

Key takeaways

• US citizens and green card holders in Korea generally keep filing a US return every year, because the treaty's saving clause preserves US citizenship-based taxation.
• Since January 1, 2026, Korea can treat you as a tax resident after 183 consecutive days of residence spread over two calendar years, not only 183 days within one year.
• A foreign national who has lived in Korea five years or less out of the last ten is generally taxed by Korea on foreign-source income only when it is paid in or remitted to Korea; Korean dual nationals are not "foreign residents" for this rule.
• The totalization agreement, not the income tax treaty, decides whether you pay into the US Social Security system or the Korean National Pension; self-employed people are generally covered where they reside.
• Korean National Pension benefits paid to a US citizen are, under Article 24 of the treaty, taxable only in Korea, and this article is an exception to the saving clause.

Do Americans living in South Korea still file US taxes?

Yes, generally. The United States taxes its citizens and resident aliens (including green card holders) on worldwide income wherever they live. Article 4(4) of the US–Korea treaty, the saving clause, lets each country tax its own citizens and residents "as if this Convention had not come into effect," subject to the exceptions in Article 4(5).

Filing threshold. For most taxpayers under 65, the obligation to file generally starts when gross income reaches the standard deduction. For tax year 2026, Rev. Proc. 2025-32 sets the standard deduction at $16,100 (single or married filing separately), $32,200 (married filing jointly) and $24,150 (head of household). These amounts are indexed annually. Self-employed people generally must file if net self-employment earnings are $400 or more, and a married person filing separately faces a much lower threshold (as little as $5 of gross income, per the Form 1040 instructions). Income you plan to exclude under the Foreign Earned Income Exclusion still counts toward the threshold.

Deadlines for tax year 2026.

• Regular due date: April 15, 2027.
• Automatic two-month extension to June 15, 2027, if your tax home and abode are outside the United States on the regular due date. Interest on unpaid tax still runs from April 15.
• Further extension to October 15, 2027, by filing Form 4868 before the June date.
• FBAR (FinCEN Form 114): due April 15, 2027, with an automatic extension to October 15, 2027.

When does South Korea treat you as a tax resident, and what does it tax?

Residency tests. Under Article 1-2 of the Income Tax Act, a resident has a domicile (주소) in Korea or a place of residence (거소) for 183 days or more. Article 2 of the Enforcement Decree judges domicile by "objective facts of living relationship," such as family and assets in Korea, and deems a domicile where your occupation usually requires 183 days' residence or your family lives with you and you are expected to stay that long. Someone arriving on a multi-year contract may be resident from arrival.

What changed in 2026. From tax years beginning January 1, 2026, 183 consecutive days spanning two tax years also make you resident, and short trips abroad such as family visits or business travel can still count toward the period.

Tax residency is not immigration status. A visa or Alien Registration Card neither makes you a tax resident nor keeps you one after you leave.

What Korea taxes (from the statute). Article 3(1) of the Income Tax Act is the charging provision. It says a resident is taxed "on all income prescribed by this Act," with a proviso: for "a foreign resident" who has had a domicile or residence in Korea "for not more than five years in total from ten years before the end of the relevant taxable period," tax on foreign-source income is imposed "only on his/her income paid in or remitted to the Republic of Korea." Non-residents are taxed only on Korean-source income (Article 3(2)). So the label is:

• Worldwide for Korean nationals (including Korean–American dual nationals) and for foreign residents past the five-in-ten-year mark;
• Korean-source plus remitted foreign-source income for foreign residents within the first five of the last ten years.

Korean-source employment income (work physically performed in Korea) is taxable in full under either category.

Unsettled point: overseas-asset gains carry their own residence condition. A June 18, 2025 NTS advance ruling (사전-2025-법규국조-0451) indicates that foreign-share gains are reportable only by residents continuously in Korea for five years or more up to the sale (reproduced on a private site, not an NTS publication) — confirm before relying on it.

Rates. National income tax runs from 6% to 45% in eight brackets, plus local income tax of 10% of the national tax (top combined rate 49.5%). The 2026 brackets are reported as 6% up to KRW 14 million, then 15%, 24%, 35%, 38%, 40%, 42%, and 45% above KRW 1 billion. A bill to index brackets from 2027 is pending.

The 19% flat rate for foreign employees. Article 18-2 of the Restriction of Special Taxation Act lets eligible foreign workers elect 19% (20.9% with local tax) on Korean employment income, with no deductions or credits, for 20 years from their first Korean workday, if they start by December 31, 2026. An August 3, 2026 reform proposal would raise it to 21% (23.1%) and extend the start deadline to December 31, 2029, from January 1, 2027; it had not been enacted as of this guide's verification date. Dual nationals should confirm eligibility.

Local filing. Employers withhold monthly and finalize most employees' tax in a year-end settlement (연말정산). Anyone with other income generally files between May 1 and May 31 of the following year, or before permanently leaving.

Recent administrative guidance.

• Overseas trust statement: residents who set up or funded an overseas trust file with the NTS by June 30 of the following year; foreign residents within the five-in-ten window are exempt; penalties up to 10% of trust assets, capped at KRW 100 million. A US revocable trust may be in scope.
• Overseas financial account report: residents whose foreign accounts together exceed KRW 500 million on any month-end file by June 30; the same five-in-ten exemption applies.

Is there a US–South Korea tax treaty?

Yes. Signed June 4, 1976, in force October 20, 1979, generally effective for taxable years from January 1, 1980. The IRS page lists no protocol. Its numbering differs from modern US treaties:

• Article 1 (Taxes covered). For Korea, income tax and corporation tax only; social contributions and local income tax are not listed.
• Article 3(2) (Tie-breaker). Permanent home ("the place where an individual dwells with his family"), then center of vital interests, habitual abode, citizenship, and mutual agreement.
• Article 4(4)–(5) (Saving clause). The United States can tax its citizens as if the treaty did not exist, except under Articles 5, 7, 24 and 27. Teacher, student and government-service benefits (Articles 20–22) survive only for people who are neither citizens nor immigrants of the taxing country.
• Article 5 (Relief). Each country credits the other's tax under its own law, using the Article 6 source rules.
• Article 12 (Dividends). Source-country withholding capped at 15%, or 10% for certain corporate shareholders owning at least 10% of voting stock.
• Article 13 (Interest) 12%; Article 14 (Royalties) 15%, or 10% for copyright and film royalties.
• Article 23 (Private pensions and annuities). Taxable only in the residence country, but subject to the saving clause for US citizens.
• Article 24 (Social security payments). Social security and other public pensions are taxable only in the paying country; for payments by Korea, the rule also covers US citizens. Because Article 24 is excepted from the saving clause, the United States generally does not tax Korean National Pension benefits paid to a US citizen, and Korea generally does not tax US Social Security paid to a US resident or citizen living in Korea.

Whether the Korean lump-sum refund of pension contributions (반환일시금) counts as a "social security payment" under Article 24 is not addressed in the treaty text, and there is no official guidance on the point. Treat it as an open question.

How do you avoid paying tax twice?

You have two main US tools, and they cannot be stacked on the same income. For the general mechanics of the FEIE, the Foreign Tax Credit and the stacking rule outside Korea-specific figures, see our guide on FEIE vs. Foreign Tax Credit.

Foreign tax credit (Form 1116). Korean income tax offsets US tax on the same foreign-source income, computed by basket (mainly general and passive). Excess credits can be carried back one year and forward ten. Korean local income tax is not treaty-covered, so its creditability rests on US domestic rules.

Foreign Earned Income Exclusion (Form 2555). For tax year 2026 you can exclude up to $132,900 of foreign earned income, indexed annually, if you meet the bona fide residence or physical presence test. It covers earned income only. It does not reduce self-employment tax, and income you exclude cannot also generate a credit.

Which tends to fit. At Korean progressive rates, the credit often eliminates US tax and banks carryovers. The exclusion may suit a low Korean effective rate, such as the flat rate on a high salary; compute rather than assume. Families should check its effect on refundable child credits. Once revoked, it generally cannot be re-elected for five years without IRS consent.

Timing. Both countries use the calendar year, so there is no fiscal-year mismatch; Korean liability is finalized in February or May, and cash-method taxpayers can elect to credit taxes as they accrue.

Social security: will you pay both?

The totalization agreement (effective April 1, 2001) is a separate instrument from the income tax treaty. On the Korean side it covers National Pension old-age, survivors and disability insurance and industrial accident contributions.

Employees. Coverage generally follows where you work. A worker temporarily sent by a US employer generally stays in US Social Security; the maximum detachment period in the agreement is commonly reported as five years, worth confirming for your specific assignment. Local hires are generally in the National Pension, whose rate rose from 9% to 9.5% on January 1, 2026, split equally, rising 0.5 points a year to 13% by 2033.

Self-employed. Under the agreement, self-employed people are covered by the country where they reside. An American freelancer resident in Korea is therefore generally in the Korean system and exempt from US self-employment tax for those years, but only with proof. Self-employed workers should attach a copy of the certificate of coverage to their US return every year.

Certificate of coverage. To be exempt from US contributions while covered in Korea, request a Korean certificate from the National Pension Service (Seoul). To stay in the US system while working in Korea, request a US certificate from SSA. US employers keep certificates on file rather than sending them to the IRS.

Effect on benefits. SSA can count Korean coverage if you have at least six US credits; Korea counts US coverage after 18 months of Korean coverage. Korea may refund contributions to a worker with under ten years of coverage who permanently emigrates, and lists US nationals as eligible.

Which US forms apply to accounts and assets in South Korea?

• FBAR (FinCEN Form 114): required if the combined maximum value of your foreign financial accounts exceeds $10,000 at any time in the year. Korean bank, brokerage, ISA and many insurance or pension accounts with cash value count. The threshold is not indexed.
• Form 8938: for taxpayers living abroad, generally required if specified foreign assets exceed $200,000 on the last day of the year or $300,000 at any time (single or married filing separately), or $400,000 and $600,000 for joint filers. It overlaps with, and does not replace, the FBAR.
• Korean banks and US persons. Under the Model 1 IGA in force since September 8, 2016, Korean institutions identify US account holders and report them through the NTS to the IRS; expect to provide your US taxpayer number. Korea has also exchanged account information under the CRS since 2017; the United States is not a CRS participant and relies on FATCA instead.
• Korea's own reporting of your non-Korean accounts (KRW 500 million test) is separate; see above.

Local pensions, retirement accounts and investment funds

National Pension. Contributions are not US-deductible; Article 24 assigns benefits to Korea.

Workplace retirement plans (퇴직연금 DB/DC), IRP and pension savings (연금저축). These are not US-qualified plans. Contributions and growth may be currently taxable in the United States, depending on plan design and on whether the plan is treated as a foreign trust. Rev. Proc. 2020-17 exempts certain tax-favored foreign retirement trusts from Forms 3520 and 3520-A if all its conditions are met. Whether a given Korean plan qualifies requires checking those conditions plan by plan; no IRS guidance addresses Korean plans specifically. Legally mandated severance pay (퇴직금) is generally compensation for US purposes when received.

PFICs. Korean mutual funds and ETFs, including inside an ISA, IRP or pension savings account, are generally PFICs, with punitive tax on gains and Form 8621 filings. For the full mechanics of the default regime and the available elections, see our guide on PFICs. Individual Korean stocks usually are not.

Running a business or company in South Korea

Entity classification comes first. Treasury's per se list includes the Korean Chusik Hoesa (주식회사), so it is always a corporation for US purposes. A Yuhan Hoesa (유한회사) or Yuhan Chaegim Hoesa (유한책임회사) is an "eligible entity": by default it is generally a corporation if all members have limited liability, but it can elect another classification on Form 8832. A sole proprietorship (개인사업자) is not a separate entity; you report it on Schedule C.

CFC exposure. A foreign corporation more than 50% owned by US shareholders who each hold 10% or more is a CFC, with annual Form 5471. From 2026, GILTI becomes net CFC tested income (NCTI): the QBAI offset is repealed, the Section 250 deduction falls to 40%, and the deemed-paid credit rises to 90%. Individuals get those benefits only through a Section 962 election; a high-tax exclusion may apply.

Self-employment tax. Without a Korean certificate of coverage, US self-employment tax generally applies, and the exclusion does not reduce it.

Buying, renting and selling property

• Selling your Korean home: US side. The US section 121 exclusion applies to a foreign main home: up to $250,000 of gain ($500,000 joint) can be excluded if you owned and used it as a main home for two of the five years before sale. Gain is computed in US dollars using the exchange rates at purchase and sale, so a stronger won alone can create taxable gain.
• Korean side. A one-household, one-home exemption applies to a resident household holding the home at least two years (and in some areas living there two years), taxing only gain attributable to price above KRW 1.2 billion. NTS guidance treats non-residents differently, so timing matters. Short holdings face much higher rates, and a preliminary return is due about two months after the month of sale. Treaty Article 15 lets Korea tax Korean real estate; you then claim a US credit.
• Currency gain on a won mortgage. If you borrow in won and the won weakens before you repay, the US may treat the drop in the dollar value of the debt as taxable foreign currency gain under IRC §988, while a loss on a personal residence loan is generally not deductible.
• Rental income. Korean rent goes on Schedule E with depreciation (generally 30 years for foreign residential property under the alternative depreciation system), with Korean tax credited in the passive basket. US rent is Korean-taxable if you are resident on a worldwide basis or remit it.
• Jeonse. There is no IRS guidance specific to jeonse deposits; ask a preparer whether any interest-like benefit or currency gain arises.

Employment, equity compensation and remote work for a US employer

Source. Treaty Article 6(6) treats personal-service income as sourced where the services are performed. Work done while physically in Korea is Korean-source, even if paid by a US company into a US account. Under Korean law, Korean-source employment income is taxable in full, without regard to the remittance rule.

Remote work for a US employer. Without Korean payroll, Korean tax is generally paid through a taxpayer association or the May return, and the employer may face Korean permanent-establishment risk. Form 673 lets a US employer reduce federal withholding if you expect to claim the exclusion. A remote worker who moved indefinitely may not fit the detached-worker rule, so US FICA and National Pension could both be claimed; get an SSA or NPS determination early.

RSUs and stock options. Korea generally taxes foreign-parent equity as employment income at vesting or exercise. The US taxes it as compensation sourced by workdays between grant and vesting, so keep a workday calendar.

State tax. Moving abroad does not automatically end US state tax residency — see our guide on state taxes after moving abroad.

Leaving South Korea

Korean exit tax. An individual who emigrates after residing in Korea five years or more of the last ten and who is a "major shareholder" of Korean shares is taxed on deemed gains on those shares at departure. For departures on or after January 1, 2027, overseas shares (including US stocks) are added, without the major-shareholder test. Exemptions apply if total overseas shares are KRW 500 million or less, and for foreign workers who worked in Korea at least 80% of the relevant period and leave within six months after their employment ends. A report is due before departure, and the return within three months after the end of the month of departure.

Final Korean return and pension refund. File your final Korean return before leaving if required, and claim any National Pension lump-sum refund.

US side. Leaving Korea does not change your US filing obligation. Renouncing citizenship or a long-term green card can trigger US expatriation tax — see our guide on the US exit tax. For 2026 the covered-expatriate tax test is $211,000 and the exclusion $910,000, both indexed.

Mistakes Americans commonly make in South Korea

1. Assuming they are non-residents because they spent under 183 days in one calendar year. Since 2026, a stay straddling New Year can count.
2. Assuming dual US–Korean nationals get the remittance rule or the flat rate designed for foreigners.
3. Remitting US investment income or gains to a Korean account in their first five years without realizing that remittance can make it Korean-taxable.
4. Buying Korean funds in an ISA or pension savings account without considering PFIC rules and FBAR reporting.
5. Freelancing in Korea and paying neither system correctly, or paying both, because no certificate of coverage was obtained.
6. Claiming the exclusion by default when the foreign tax credit would produce a better result and carryovers.
7. Forgetting the overseas trust and overseas account reports once they pass five years of Korean residence.
8. Leaving Korea in 2027 or later with a large US brokerage account and no exit-tax analysis.

Checklist

Before moving: ask about a certificate of coverage; inventory US trusts and brokerage holdings; confirm your US broker accepts foreign residents.

First 90 days: record your arrival date; confirm whether you are resident from arrival; decide on the flat-rate election; add Korean accounts to your FBAR list.

Every year: Korean settlement or May return; US return by June 15 (October 15 with Form 4868); FBAR; Form 8938 if required; Form 1116 or 2555; certificate attached if self-employed; after five years, Korean account and trust reports by June 30.

Before leaving: exit-tax review (especially from 2027); home sale timing; final Korean return; National Pension refund claim.

Frequently asked questions

Do I have to file US taxes if I live in South Korea?

Generally yes, if your gross income exceeds the filing threshold, even if you owe nothing after credits or the exclusion.

Is my Korean salary taxed by the US?

It is reportable; the foreign tax credit or the 2026 exclusion ($132,900) usually offsets it.

Is Korean National Pension taxable in the US?

Under treaty Article 24, benefits paid by Korea to a US citizen are generally taxable only in Korea.

Do I pay US Social Security tax while working in Korea?

It depends on who employs you and whether you are self-employed. The totalization agreement assigns coverage; a certificate of coverage proves the exemption.

Does Korea tax my US 401(k) or brokerage account?

If you are Korean-resident on a worldwide basis, potentially yes. In your first five years as a foreign resident, foreign-source income is generally taxed only if paid in or remitted to Korea.

Do I need to report Korean bank accounts to the IRS?

Yes, on the FBAR if all foreign accounts together exceed $10,000 at any time, and possibly on Form 8938.

When to hire a professional

• Cross-border return with Korean salary, US investments and credit carryovers: a US enrolled agent or CPA experienced with expatriates.
• Residency, flat-rate election, May return and exit tax: a Korean licensed tax accountant (세무사).
• A Korean company with US owners (Form 5471, NCTI, Section 962): a US international tax CPA or attorney.
• Korean pension plans, ISAs and funds (PFIC, Form 3520 questions): a US preparer with PFIC experience.
• Social security coverage questions for remote workers: SSA's Office of International Programs or the National Pension Service, plus your employer's payroll adviser.
• Missed FBARs or returns: a US tax attorney, who can advise on IRS compliance programs — see our guide on the Streamlined Filing Compliance Procedures.

Sources

Source	URL	Used for	Page date
IRS — US–Korea Income Tax Convention (1976)	https://www.irs.gov/pub/irs-trty/korea.pdf	Treaty articles	Signed 04-Jun-1976
US Treasury — Technical Explanation of the 1976 Convention	https://www.stayexempt.irs.gov/pub/irs-trty/koreatech.pdf	Treaty interpretation	1976
IRS — Rev. Proc. 2025-32	https://www.irs.gov/pub/irs-drop/rp-25-32.pdf	2026 standard deduction, FEIE, expatriation thresholds	2025
IRS — Instructions for Form 3520-A (Rev. Proc. 2020-17)	https://www.irs.gov/node/40536	Foreign retirement trust exemption	Accessed 17-Oct-2026
U.S. Treasury — FATCA agreements table	https://home.treasury.gov/policy-issues/tax-policy/foreign-account-tax-compliance-act	Model 1 IGA, 8-Sep-2016	Accessed 17-Oct-2026
SSA — Totalization Agreement with Korea	https://www.ssa.gov/international/Agreement_Pamphlets/korea.html	Agreement overview, effective 1-Apr-2001	Accessed 17-Oct-2026
SSA — International Update, April 2025	https://www.ssa.gov/policy/docs/progdesc/intl_update/2025-04/2025-04.pdf	National Pension rate increase	Apr-2025
National Pension Service — US–Korea agreement	https://minwon.nps.or.kr/jsppage/english/agreement/agreement_02_03_01.jsp	Certificate of coverage procedure	Accessed 17-Oct-2026
Korea Income Tax Act, English translation (KLRI)	https://elaw.klri.re.kr/eng_service/lawTwoView.do?hseq=28557	Residency and charging provisions	Accessed 17-Oct-2026
Enforcement Decree of the Income Tax Act (KLRI)	https://elaw.klri.re.kr/eng_service/lawViewContent.do?hseq=63464	Domicile test detail	Accessed 17-Oct-2026
KOTRA Foreign Investment Ombudsman — flat-rate notice	https://ombudsman.kotra.or.kr/ob-en/bbs/i-2650/detail.do?ntt_sn=654	19% flat rate, 20-year period	29-Dec-2022
Invest Korea / NTS — Overseas Financial Account Report	https://www.investkorea.org/ob-en/bbs/i-2650/detail.do?ntt_sn=657	KRW 500M reporting threshold	Accessed 17-Oct-2026
KPMG; Crowe; PwC; Deloitte; Vialto (secondary)	—	Issue-spotting only: 2026 brackets, reform proposals, exit tax mechanics, NCTI/OBBBA	2025–2026
Korea Bridge (secondary)	https://www.koreabridge.net/post/pension-contributions-rising-5-through-2033	National Pension rate schedule	2025

A note on scope: this guide is general information, not tax or legal advice. Whether a given fact pattern — a Korean pension plan, an ISA, a company you control — triggers the rules described here depends on your own situation. Get advice from a US preparer experienced with Forms 1116, 5471, 8621 and 8938 and a Korean licensed tax accountant (세무사) before you rely on anything in this guide.