South Korean taxes for Americans: the 19% option, residency and your US return

Two tax systems, one paycheck. Korea taxes you once you live there, the US taxes you because you're a citizen, and the trick is making sure you only really pay once.

The short version

• Residency: you're a Korean tax resident if you have a domicile in Korea or a residence there for 183 days or more in a tax year [1].
• Rates: Korea's national income tax runs from 6% to 45%, plus a local income tax of 10% of the national tax [2].
• The 19% option: foreign employees who start work in Korea by December 31, 2026 can elect a single 19% rate on their salary instead, for up to 20 years, but they give up most deductions and credits [3].
• On the US side: you still file a US return. Most Americans in Korea use either the foreign earned income exclusion (USD 130,000 for 2025, USD 132,900 for 2026) or the foreign tax credit [4].
• Social Security: the US–Korea totalization agreement, in force since April 1, 2001, stops you from paying into both systems at once [5].

USD conversions use the Federal Reserve H.10 rate of October 30, 2026 (USD 1 = KRW 1,333.99), rounded. All of this is general information. A US expat tax preparer (or a Korean tax accountant) can check your situation.

Are you a Korean tax resident?

Korea looks at where you live, not your passport. Based on PwC's summary of Korean law (last reviewed July 2, 2026) [1]:

• Domicile in Korea makes you a resident, whatever your day count.
• 183 days or more of residence in a tax year makes you a resident. For tax years starting on or after January 1, 2026, 183 consecutive days spread across two tax years also counts.
• Your job and family matter. If your work generally requires you to live in Korea for 183 days or more, or your family and major assets are there, you can be treated as resident.
• Dual residents fall back on the tie-breaker rules in the US–Korea tax treaty.

Nonresidents are generally taxed only on Korean-source income. Residents are taxed more broadly, but there's a break for newcomers: foreign residents who've lived in Korea five years or less in the last ten are taxed on foreign dividends and interest only if they're paid in Korea or brought into Korea [3]. So a US brokerage account you leave alone isn't usually pulled into your Korean return during your first few years.

Korean income tax rates

These rates apply to income from January 1, 2023 onward [2]:

On top comes the local income tax, 10% of your national tax, paid to the city or province where you live [2]. So a 24% bracket really costs you 26.4%. National Pension and National Health Insurance contributions come out of your pay too.

The 19% option for foreign employees

This is the feature most Americans in Seoul ask about. Under PwC's summary [3]:

• Who: foreign employees and expatriates who start working in Korea no later than December 31, 2026.
• What: a single 19% rate on employment income (plus 10% local tax on that, so 20.9% all in), instead of the 6% to 45% scale.
• How long: 20 years from your first day of work in Korea.
• The catch: you lose most other income deductions, exemptions and credits.
• Not for: people working for a related company, such as one they or their relatives control.
• How to elect: through your employer's year-end settlement or your annual return. To have 19% withheld from each paycheck, you apply to the tax office.

Run the numbers both ways. At modest salaries, the regular scale plus deductions usually beats 19%. At higher salaries, 19% can save a lot. The start-date deadline is worth watching too: it's set in Korean tax law, so if you're arriving in 2027, check whether the latest tax law changes have pushed it past 2026.

How filing works in Korea

The tax year is the calendar year [6]. If you only have salary, your employer withholds tax every month and does a year-end settlement (yeonmal jeongsan) early in the following year, filing it with the tax office by March 10 [6]. You hand over receipts for deductions, and that's usually the end of it. If you have other income, such as freelance work or rental income, you file a return between May 1 and May 31 [6]. If you leave Korea for good, file before you go, covering January 1 to your departure date [6].

How Korea fits with your US return

Uncle Sam taxes his citizens wherever they live, so you'll file a US return every year. You have two main tools to avoid double tax:

Some quick rules of thumb, not advice:

1. If your Korean tax is higher than your US tax would be, the foreign tax credit often wipes out US tax on your salary and can build up carryovers.
2. If you elect 19% or sit in a low bracket, the exclusion may leave you with less US tax.
3. Switching back and forth has limits. Once you revoke the exclusion, you generally can't use it again for five years without IRS consent, so pick carefully.

The US–Korea tax treaty

The US and Korea signed an income tax treaty in 1976, and the IRS still lists the 1976 treaty and its technical explanation as the current documents [7]. It sets tie-breaker rules for dual residents and reduced rates on some investment income. Like most US treaties, it doesn't stop the US from taxing its own citizens on their salary, so for most Americans it matters less than the exclusion and credit above.

Social Security: the totalization agreement

The US–Korea totalization agreement entered into force on April 1, 2001 [5]. In general [5][8]:

• Sent to Korea by a US employer for five years or less? You can usually stay in US Social Security and skip Korea's National Pension, with a certificate of coverage.
• Hired locally in Korea? You'll usually pay into Korea's National Pension instead.
• Self-employed? You're covered by the country where you live. If that's Korea, the SSA says to attach your certificate of coverage to your US return every year, so you don't also owe US self-employment tax [8].
• Certificates for Korean coverage come from the National Pension Service in Seoul [8].

When you leave Korea, you may be able to claim back some National Pension contributions. See Korea's national pension and the lump-sum refund.

Reporting your Korean accounts

Your Korean bank account is a foreign account to the US government:

• FBAR (FinCEN Form 114): required if your foreign accounts together top USD 10,000 at any time in the year [9]. That's easy to hit with a Korean deposit sitting in the bank before you pay a landlord.
• Form 8938 (FATCA): for Americans living abroad, required if your foreign financial assets exceed USD 200,000 on the last day of the year or USD 300,000 at any time (single), or USD 400,000 and USD 600,000 for joint filers [10].

Korean banks will ask you for US tax details under FATCA when you open an account. See banking in South Korea as an American.

Want to compare notes with others who've filed both returns? Ask in our community group for Americans in South Korea.

Sources

1. PwC Worldwide Tax Summaries: Republic of Korea, individual residence (reviewed July 2, 2026)
2. PwC Worldwide Tax Summaries: Republic of Korea, taxes on personal income (reviewed July 2, 2026)
3. PwC Worldwide Tax Summaries: Republic of Korea, income determination (reviewed July 2, 2026)
4. IRS: Figuring the foreign earned income exclusion
5. SSA: US international Social Security agreements
6. PwC Worldwide Tax Summaries: Republic of Korea, tax administration
7. IRS: Korea tax treaty documents
8. SSA: US–Korea Social Security agreement
9. FinCEN: Report foreign bank and financial accounts
10. IRS: Comparison of Form 8938 and FBAR requirements

Keep reading

• Korea's national pension and the lump-sum refund
• Banking in South Korea as an American
• Cost of living in Seoul vs Los Angeles
• FBAR: reporting your foreign bank accounts