The United States and South Korea have both an income tax treaty and a Social Security (Totalization) Agreement, which help prevent double taxation for Americans living in the country. However, US citizens must navigate complex rules for reporting Korean statutory severance (toejikgeum / 퇴직금), the 19% foreign worker flat-tax election, National Pension Scheme (NPS) contributions, and local investments. Common Korean investment products like KOSPI ETFs (KODEX, TIGER series) are classified as Passive Foreign Investment Companies (PFICs), while local retirement wrappers (IRPs) and corporations (Jusik Hoesa) trigger intricate reporting on Form 8621, Form 3520, and Form 5471.
US filing basics every American abroad must know
US citizens and green-card holders are taxed on worldwide income wherever they live, and usually must file Form 1040 once gross income exceeds the IRS threshold ($15,750 for single filers, $31,500 for married filing jointly, and $23,625 for head of household for 2025), even when no tax is ultimately due. The tools that reduce double taxation are the Foreign Earned Income Exclusion (FEIE, up to $130,000 for 2025 under IRC §911) and the Foreign Tax Credit. Neither is automatic. The FEIE requires a tax home in a foreign country plus either the bona fide residence test or 330 full days abroad in a 12-month period, and it reaches earned income only. The Foreign Tax Credit is figured separately for each income category under IRC §904 and is capped at the US tax on the foreign income in that category, so it reduces double taxation without guaranteeing that none remains.
Two reporting rules catch most filers in South Korea: the FBAR (FinCEN Form 114), required when foreign financial accounts exceed $10,000 in aggregate at any point in the year, and Form 8938 (FATCA) for specified foreign assets above the applicable threshold. Both can carry penalties even when no tax is owed. If you are behind, the Streamlined Filing Compliance Procedures are the usual path back for non-willful taxpayers. They run on two tracks: the foreign track carries no offshore penalty but requires meeting the program's non-residency test, and the domestic track carries a 5% offshore penalty but works through amended returns, so it does not fit someone who never filed at all. Tax and interest on the catch-up years are owed whichever route applies.
US tax treaty with South Korea
The U.S.-South Korea income tax treaty prevents double taxation and fiscal evasion. A critical feature for U.S. citizens is the saving clause found in Article 4(4), which permits the U.S. to tax its citizens on their worldwide income as if the treaty did not exist. Because of this, Americans in Korea cannot simply use the treaty to exempt their Korean income from U.S. tax. Instead, the treaty's primary benefits are reducing Korean withholding taxes on Korean-source income, providing rules to determine tax residency, and establishing a framework for claiming U.S. foreign tax credits for taxes paid to Korea.
Article 12 (Dividends). Sets maximum withholding rates on dividends paid from a source in one country to a resident of the other, with a lower rate for significant corporate shareholders.
Article 13 (Interest). Establishes a maximum withholding tax rate on interest income paid from one country to a resident of the other.
Article 14 (Royalties). Sets maximum withholding rates on royalties, providing a lower rate for royalties derived from copyrights or artistic works.
Article 4(4) (Saving Clause). Allows the United States to tax its citizens and residents as if the treaty had not entered into force. This provision preserves the U.S. system of worldwide taxation for its citizens, making mechanisms like the Foreign Tax Credit essential.
Article 5 (Elimination of Double Taxation). Provides the statutory framework for the US Foreign Tax Credit (Form 1116), allowing US citizens in Korea to credit Korean national and local income taxes against US federal tax liabilities.
Article 20 (Teachers and Researchers). Exempts qualifying visiting professors and researchers from host country income tax on teaching and research remuneration for up to two years.
Article 21 (Students and Trainees). Exempts qualifying foreign scholarship grants and maintenance remittances from host country taxation.
Article 23 (Private Pensions and Annuities). Assigns primary taxing rights on private pensions to the country of residence, though the savings clause preserves US worldwide taxation for citizens.
| Income type | Treaty rate | Statutory rate | Notes |
|---|---|---|---|
| Dividends | 15% | 20% base rate + 10% local surtax on the tax (effective 22%) | 10% for dividends paid to a corporate recipient owning at least 10% of the paying corporation's voting stock. |
| Interest | 12% | 20% base rate + 10% local surtax on the tax (effective 22%) | |
| Royalties | 15% | 20% base rate + 10% local surtax on the tax (effective 22%) | 10% for royalties from copyrights or artistic works. |
Because of the saving clause, a U.S. citizen generally cannot use the treaty to exempt income from U.S. tax. The treaty's main functions for U.S. expats are to support the claim for foreign tax credits to avoid double taxation and to reduce Korean tax withheld on certain types of income.
South Korean Pensions and US Tax
South Korea's pension and severance landscape presents several critical US tax considerations:
- National Pension Scheme (NPS / 국민연금): The mandatory public pension requires matching 4.5% contributions (rising to 4.75% for 2026). Employee contributions are paid from after-US-tax wages and are not deductible on Form 1040. Employer contributions are treated as a payroll tax on the employer and are excluded from US gross income. The NPS balance is explicitly exempt from Form 8938 (foreign social security exception) and FBAR reporting.
- Statutory Severance Pay (Toejikgeum / 퇴직금): Severance paid under the Korean Labor Standards Act is taxed favorably in Korea as retirement income (퇴직소득). However, the US treats it as ordinary compensation income in the year received. Because Korean effective tax on severance is low (often 2%–6%), the Foreign Tax Credit leaves a significant residual US tax liability unless sheltered by available FEIE cap under IRC §911.
- Individual Retirement Pensions (IRP / 개인형퇴직연금): Generally classified by US practitioners as foreign grantor trusts, triggering potential Form 3520 / 3520-A reporting unless exempted under Rev. Proc. 2020-17. Underlying Korean funds held within an IRP constitute PFICs, requiring Form 8621.
Investments, property, and capital gains in South Korea
Investing in South Korea requires careful attention to U.S. tax rules that do not align with local treatment. Many common South Korean investment funds and ETFs, such as those in the popular TIGER and KODEX series, are classified as Passive Foreign Investment Companies (PFICs) by the IRS. Holding PFICs requires filing Form 8621 for each fund, a complex form. Without specific, timely elections (like a QEF or mark-to-market election), any gains or distributions from a PFIC are subject to a punitive default tax regime that includes ordinary income rates and an interest charge, regardless of how the income is characterized in Korea.
Regarding capital gains from selling assets like real estate, the U.S. taxes its citizens on worldwide gains. Where South Korea also taxes the gain, a U.S. citizen can claim a foreign tax credit for the Korean tax paid on it, capped at the U.S. tax on foreign-source income in the same category. The credit is only as good as the Korean tax actually charged: where Korea exempts or lightly taxes a disposal, there is little or nothing to credit and the U.S. tax stands. The gain must still be calculated and reported according to U.S. rules, in U.S. dollars.
Self-employment and companies in South Korea
Operating a business or being self-employed in South Korea has significant U.S. tax implications. If you own an interest in a Korean corporation, such as a Jusik Hoesa (stock company) or Yuhan Hoesa (limited liability company), it may be classified as a Controlled Foreign Corporation (CFC). This happens when U.S. shareholders together own more than 50% of the company by vote or by value, counting only those U.S. shareholders who each own at least 10%. Your own 10% stake makes you a U.S. shareholder for that test but does not by itself make the company a CFC. As a U.S. shareholder of a CFC you must file Form 5471 annually, and the form's other categories can apply on control, on acquiring a stake that reaches 10%, on acquiring another 10% on top, on disposing of enough to drop below 10%, or on becoming a US person while already holding 10%, even where no CFC exists. This can result in you being taxed in the U.S. on your share of the company's earnings under the GILTI (Global Intangible Low-Taxed Income) or Subpart F rules, even if the company retains all its profits and pays no dividends.
For self-employed individuals, the U.S.-South Korea Social Security (Totalization) Agreement is crucial. This agreement prevents double social security taxation. If you are self-employed and covered by South Korea's National Pension Scheme, you can obtain a Certificate of Coverage from the Korean National Pension Service. By attaching this certificate to your U.S. tax return, you are exempt from paying U.S. self-employment taxes on that same income. Without this certificate, you would be liable for both Korean social contributions and U.S. self-employment tax.
Worked examples
English Teacher at a Seoul Hagwon (Catch-up Filings) (2025)
A US citizen teaching in Seoul earns KRW 40,000,000 (~$30,000 USD) annually with Korean income tax withheld by her employer. Having missed three years of US filings, she uses the Streamlined Foreign Offshore Procedures (SFOP) to submit three years of Form 1040 and six years of FBARs. She claims the Foreign Tax Credit (Form 1116) rather than the FEIE to preserve her eligibility for the refundable Additional Child Tax Credit in future years. Because her Kookmin Bank accounts peaked above $10,000, her FBAR submission ensures full compliance with a 0% offshore penalty.
Corporate Executive Departing Korea with Severance (2025)
A US citizen leaves a Korean technology firm after 7 years of service, receiving KRW 100,000,000 (~$75,000 USD) in statutory toejikgeum on top of a $120,000 final-year salary. While Korea assesses only ~4% tax on the severance, the IRS treats the full $75,000 as ordinary income. His regular salary consumes the $130,000 FEIE cap, leaving the severance fully subject to US tax. He claims the Foreign Tax Credit on Form 1116 for the Korean severance tax paid, but owes residual US tax at his 24% marginal rate.
Self-Employed Consultant with Korean Brokerage Account (2025)
A US citizen operates as a registered sole proprietor (개인사업자) in Busan, earning $90,000 net profit, and holds KRW 30,000,000 across two KODEX ETFs. Under the US-Korea Social Security Totalization Agreement, he secures a Certificate of Coverage from the Korean NPS, exempting him from the 15.3% US self-employment tax. For his KODEX ETFs, he files two Forms 8621 under the Section 1291 PFIC regime and reports the brokerage account on FinCEN Form 114.
Common mistakes for Americans in South Korea
- Forgetting to report Individual Retirement Pensions (IRP) on the FBAR and Form 8938.
- Treating Korean ETFs like KODEX or TIGER as simple stocks, thereby failing to file Form 8621 for Passive Foreign Investment Companies (PFICs).
- Assuming a Korean corporation (Jusik Hoesa) has no U.S. tax impact until dividends are paid, ignoring the complex CFC, Form 5471, and GILTI reporting rules.
- Incorrectly deducting employee contributions to the Korean NPS on a U.S. tax return.
- For self-employed persons, failing to obtain a Certificate of Coverage and paying U.S. self-employment tax when it could have been avoided under the totalization agreement.
- Overlooking the foreign trust reporting requirements (Forms 3520 and 3520-A) for Korean Individual Retirement Pensions (IRPs) that do not qualify for the exemption under Rev. Proc. 2020-17.
- Believing the tax treaty allows them to exclude Korean income from their U.S. return, misunderstanding the power of the saving clause.
- Failing to calculate and report capital gains on the sale of a Korean home on a U.S. return, assuming local tax rules apply.
- Assuming Korean statutory severance (toejikgeum) is tax-free in the US because Korea taxes it at low retirement rates.
- Electing the Korean 19% flat-tax rate without modeling the resulting reduction in creditable Foreign Tax Credits on Form 1116.
- Failing to report Section 988 foreign currency gains when a large KRW Jeonse housing deposit is refunded and repatriated.
- Assuming Korean ISAs (개인종합자산관리계좌) provide US tax shelter benefits, neglecting annual US dividend/gain reporting and PFIC Form 8621 filings.
South Korea tax FAQ
Do I have to report my Korean National Pension (NPS) account to the U.S. government?
No. The Korean National Pension Scheme (NPS) is a foreign social security account and is exempt from FBAR and Form 8938 reporting.
Are Korean ETFs like TIGER or KODEX treated differently from U.S. ETFs?
Yes, very differently. For U.S. tax purposes, these are almost always considered Passive Foreign Investment Companies (PFICs). This triggers a requirement to file Form 8621 for each fund. The default tax treatment for PFICs is extremely unfavorable, involving high tax rates and interest charges. It is a significant compliance trap for U.S. investors in Korea.
I own a small company in Korea. What are my main U.S. tax obligations?
The company is a Controlled Foreign Corporation (CFC) when U.S. shareholders together own more than 50% of it by vote or by value, counting only those U.S. shareholders who each own at least 10%. If that test is met and you are one of those shareholders, you must file Form 5471 annually, which is a very complex return. Form 5471 also has categories that bite without a CFC, such as controlling the company, acquiring a stake that reaches 10%, acquiring another 10% on top, disposing of enough to drop below 10%, or becoming a US person while already holding 10%. You may also have to include some of the company's profits (known as Subpart F income or GILTI) in your personal U.S. income, even if the company doesn't distribute any dividends to you.
I'm self-employed in Korea. Do I have to pay both Korean social contributions and U.S. self-employment tax?
No, you should not have to. The U.S.-South Korea Totalization Agreement prevents this double taxation. If you are paying into the Korean National Pension Scheme, you can request a Certificate of Coverage from the Korean authorities. Attaching this certificate to your U.S. tax return exempts you from paying U.S. self-employment (Social Security and Medicare) taxes on that income.
How does the U.S.-Korea tax treaty help me reduce my U.S. taxes?
The treaty's main benefit for a U.S. citizen in Korea is not direct tax exemption, due to the treaty's saving clause. Instead, it helps by allowing you to claim a Foreign Tax Credit for income taxes you pay to Korea. Since Korean tax rates are often comparable to or higher than U.S. rates, these credits can significantly reduce or eliminate your U.S. tax liability on your Korean-source income. The treaty also reduces Korean withholding tax on Korean-source income you might receive.
What is an IRP (Individual Retirement Pension) and how does the IRS view it?
An IRP is a private retirement account in Korea. The IRS generally treats these accounts as foreign trusts. This means you may have to file Form 3520 (for contributions) and ensure Form 3520-A (an annual information return) is filed. However, eligible tax-favored foreign retirement trusts are exempt from Form 3520 and 3520-A reporting under Rev. Proc. 2020-17. The account must still be reported on your FBAR and Form 8938.
If I sell my apartment in Seoul, do I report it to the IRS?
Yes. The U.S. taxes its citizens on their worldwide capital gains. You must report the sale on your U.S. tax return (typically on Form 8949 and Schedule D), calculating the gain in U.S. dollars according to U.S. tax principles. If the apartment was your main home, the IRC section 121 exclusion of up to $250,000 of gain ($500,000 on a joint return) applies to a home abroad on the same terms as one in the U.S., subject to the ownership and use tests. Korean income tax you pay on the gain can be claimed as a foreign tax credit, though the credit is capped at the U.S. tax on your foreign-source income in that category. Watch the case where Korea charges little or nothing on the sale: there is then no Korean tax to credit, and any gain above the section 121 exclusion is taxed by the U.S. with nothing to offset it.
What is the 'saving clause' and why does it matter?
The saving clause, found in Article 4(4) of the treaty, is a standard provision in most U.S. tax treaties. It essentially says that the United States reserves the right to tax its own citizens and residents as if the treaty did not exist. This is the reason why a U.S. citizen living in Korea cannot simply point to a treaty article to exempt their salary from U.S. tax. You must still file a complete U.S. tax return and use provisions within the U.S. tax code, like the Foreign Tax Credit, to reduce your tax.
How is Korean statutory severance pay (toejikgeum / 퇴직금) taxed on a US tax return?
Statutory severance pay (toejikgeum) is treated as ordinary compensation income on US Form 1040 in the year received. Although South Korea applies a separate, highly favorable retirement income (퇴직소득) tax rate, the IRS does not recognize this exemption. You can claim a Foreign Tax Credit (Form 1116) for the Korean tax paid, but because Korean tax is low, a residual US tax liability is common.
What is the 19% flat-tax rate for foreign workers in Korea and how does it affect US taxes?
Foreign workers in South Korea can elect a flat 19% income tax rate (excluding local surtax) on Korean employment income until December 31, 2026. While beneficial in Korea for high earners, it reduces Korean taxes paid and therefore reduces the Foreign Tax Credit available on Form 1116, which can increase your US tax liability. Both returns should be modelled together before electing.
What is the Jeonse (전세) housing deposit and how is it treated for US taxes?
Jeonse is a Korean lease system where the tenant pays a large lump-sum deposit (typically 50%–80% of property value) in lieu of monthly rent. The deposit itself is a capital receivable. However, when the KRW deposit is refunded at lease end and converted back to USD, any currency appreciation is taxable as ordinary income under IRC §988. If held in a Korean bank account in your name, the account is reportable on the FBAR and Form 8938.
I naturalized as a US citizen through marriage to a US citizen. Do I have to give up my Korean citizenship, and what does the IRS want?
Yes, Korean nationality is lost automatically the moment the US naturalization oath is taken (Korea Nationality Act, Article 15), whether or not it is reported to Korea. Separately, and on its own timeline, US tax residency actually started years earlier, at the green card, not at naturalization. The full mechanism, including what the loss-of-nationality report does and does not do, is covered in a dedicated guide.
Sources and last reviewed
- IRS, U.S.-South Korea Income Tax Convention (verified 2026-06-07)
- SSA, US-South Korea totalization agreement (verified 2026-06-07)
- IRS, Instructions for Form 5471 (verified 2026-06-07)
Reviewed by Ilya Fayerman, Esq. (NY Bar) on
Asia depth guide
For filing context specific to South Korea in APAC, see the dedicated guide on US Tax Asia, South Korea (separate site, complementary content).
Common services needed by expats in South Korea
Most Americans abroad in South Korea need help with at least one of the following core compliance areas, which frequently interact:
- US expat tax returns, Form 1040 with FEIE, FTC, treaty positions, and any required state returns.
- FBAR reporting, FinCEN Form 114 for foreign financial accounts exceeding $10,000 aggregate at any time during the year.
- Form 8938 (FATCA), IRS disclosure of specified foreign financial assets when thresholds are met.
- Streamlined catch-up filing, For eligible non-willful taxpayers with prior unfiled years.
Discuss your South Korea return
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