Income Tax for Foreigners in Korea: Residency, the 19% Flat Rate and May Filing (2026)

How does income tax for foreigners in Korea work?

Korea taxes foreigners on the same basis as citizens: if you have a home base here or stay 183 days or more, you are a resident taxed on worldwide income at 6 to 45 percent, and if not, you are taxed only on Korean-source income. Everything else in this guide, from the 19% flat rate to the May filing, hangs off that one classification.

I am writing this for Americans, because the US adds a second layer that most “Korea tax guides” skip. You may owe nothing extra to the IRS, but you will still file with it, and the order in which you do things in Korea affects what you can claim in the US. The Korean rules below come from the National Tax Service’s own materials and the statutes; where I could not confirm a detail on an official page, I say so. Facts are as of October 2026.

Two quick orientation points. First, Korean employers withhold tax every month and settle it in February, so most salaried foreigners never see a bill. Second, the exceptions, meaning freelancers, side income, two employers, a mid-year departure, are where people get penalties.

Am I a tax resident in Korea? The 183-day test

A resident under the Income Tax Act is a person who has a domicile in Korea or has had a residence (거소) in Korea for 183 days or more. A non-resident is anyone who is not a resident. The National Tax Service’s guidance on non-resident determination lays out both limbs.

The part people miss is “domicile.” It is judged by facts, not paperwork. Under the Enforcement Decree, you are treated as having a domicile in Korea if your job normally requires you to live here 183 days or more, or if you have family living with you in Korea and your work and assets indicate you will stay that long. So a 12-month employment contract with an ARC card is usually a resident case from the day you arrive, not from day 183. Guidance on counting days says the clock starts the day after entry.

Situation	Likely status	Why
12-month teaching or engineering contract, living in Korea	Resident	Job normally requires 183+ days
3-month visit with a Korean client, family abroad	Usually non-resident	Under 183 days, no domicile
Remote worker, 7 months in Korea, foreign employer pays you	Resident (by days)	183+ days of residence
Spouse and kids in Seoul, you travel half the year	Possibly resident	Family and assets can create a domicile

Why it matters: a resident is taxed on worldwide income, files a comprehensive return when needed, and can claim deductions. A non-resident has narrower deductions and, on income without a Korean payroll, a flat withholding that is typically around 20 percent unless a treaty lowers it. If your status is borderline, document your days with passport stamps and ask a tax agent before the May deadline, not after.

Do residents get taxed on foreign income too?

Yes, with a generous exception for short-term foreigners. A resident is normally taxed on worldwide income, but if you have had a domicile or residence in Korea for a combined five years or less in the ten years before the tax year ends, foreign-source income is taxed only to the extent it is paid in or remitted to Korea. That is how the rule was summarized in the guidance I reviewed, and it is the reason a new arrival with a US rental property or dividends is often fine for a few years.

Then the clock runs out. After the fifth year of residence, worldwide income comes into the Korean net. This is the single most common surprise for long-term expats, and it is also why you should keep a simple log of the years you were a resident.

For Americans, the practical consequence is that the first five years are the cheap ones. After that, you will report foreign income in Korea, and the US foreign tax credit becomes more important. My foreign tax credit explainer walks through the basic mechanics.

What are the Korean income tax rates and the 19% flat option?

Residents pay progressive rates from 6 to 45 percent, plus a local income tax of 10 percent of the tax amount. The foreign-worker flat option lets eligible employees pay 19 percent of Korean employment income instead.

Taxable income (KRW)	Rate
Up to 14 million	6%
14 to 50 million	15%
50 to 88 million	24%
88 to 150 million	35%
150 to 300 million	38%
300 to 500 million	40%
500 million to 1 billion	42%
Over 1 billion	45%

Treat that table as a map, not a calculator: bracket boundaries are applied to taxable income after deductions, and the current schedule is on the National Tax Service site. What matters for planning is the shape. A mid-career salary lands you around 24 percent marginal, and top earners hit 35 percent and above.

The 19% option comes from Article 18-2 of the Restriction of Special Taxation Act. Summaries I found describe it this way:

• It applies to foreign executives and employees, not day laborers.
• It covers Korean employment income only, and up to 20 years from your first day of work in Korea.
• The qualifying condition is starting to work in Korea by December 31, 2026.
• If you choose it, the usual tax exclusions, deductions, reductions and credits do not apply.
• You apply with a form, the foreign worker flat-rate election, at year-end settlement or in your May filing. If you want 19% withheld monthly, a separate application is due by the 10th of the month after you start work.

Add local tax and the effective rate is around 20.9 percent. Compare that to your honest marginal rate. If your taxable income is in the 35 percent band or higher, the flat rate usually wins by a wide margin. If your pay is modest and you have dependents, medical expenses and pension credits, the regular method may come out lower, because the flat rate throws away every deduction. The only reliable way to know is to run both versions with your payroll team.

One more caveat, and it is a big one for readers who haven’t yet moved. The December 31, 2026 start-date cutoff is what the sources I could verify say. An advisory alert from KPMG describes an August 2026 reform proposal to raise the rate to 21 percent and extend the cutoff to the end of 2029. I could not confirm it passed. Until you see final law, assume the cutoff is the end of this year.

Should I take the 19% flat rate or the regular method?

My view: take the flat rate if your gross Korean pay is high and you do not have many credits to claim, and think twice if you plan to pay into a pension or claim big medical or education items. It is also a simpler life. One flat figure, no paperwork for deductions, fewer surprises in February.

The election is annual and generally applied to the whole year of Korean employment income. Because you lose deductions, the comparison should include everything you would have claimed on the regular route.

Factor	19% flat	Regular method
Rate	19% (about 20.9% with local tax)	6 to 45% progressive
Deductions and credits	None	Standard, plus pension, medical, education, housing items
Paperwork	Minimal	Receipts at year-end settlement
Best for	High earners, few deductions	Moderate pay, dependents, many credits
Who is eligible	Foreign employees who started work by the cutoff	Everyone

A worked example without numbers I cannot verify: if you earn a high salary and your regular marginal rate is 35 percent, every extra won is taxed at 35 percent on the regular method but 19 percent under the flat option. That gap is often worth far more than the standard credits. For a person at the 15 to 24 percent marginal level, the gap is small and the lost deductions can erase it.

What are year-end settlement and May filing, and when do I do each?

Year-end settlement is your employer reconciling the tax it withheld all year, using your deduction paperwork submitted in January. May filing is the comprehensive income tax return you file yourself on HomeTax, covering the previous calendar year, from May 1 to May 31.

Most salaried foreigners with one employer and no other income only do year-end settlement. You need the May return if any of the following is true:

1. You earned freelance, business, rental or other income.
2. You had two or more employers during the year and did not combine them at year-end.
3. You had foreign income that is taxable in Korea.
4. You want to change a missed deduction after year-end.

If you are in the second category, my year-end settlement versus income tax guide explains the split, and the May comprehensive income tax filing guide covers the screens. The May window is set by the National Tax Service, which publishes the schedule each year; if May 31 lands on a weekend it moves to the next business day.

Event	Typical timing
Collect deduction documents	January
Employer year-end settlement	January to February payroll
Comprehensive income tax filing	May 1 to 31
Flat-rate election (withholding)	By the 10th of the month after starting work

How are freelancers and side income taxed?

Freelancers in Korea usually have 3.3 percent withheld by the client (3 percent income tax plus 0.3 percent local tax), which is a prepayment, not the final bill. In May you report your entire year of income, subtract expenses, and either pay more or get money back.

If you are a foreigner teaching English on the side, writing for Korean media or doing contract design, check two things. First, your visa. A work visa is tied to a specific employer or activity, and income outside it can create an immigration problem long before it creates a tax problem. Second, your registration: ongoing business activity may require a business registration and VAT. Ask a tax agent, because the line between a one-off gig and a business is a question of fact.

A failure case, labeled as a composite I have seen in expat forums: a foreign engineer with a Korean employer took a side translation contract, had 3.3 percent withheld, and assumed that closed the matter. The side income never showed on the year-end settlement, no May return was filed, and the tax office later sent a notice with a penalty. Nothing was hidden. It simply was never reported, and the withholding didn’t count as filing. The fix was an after-the-fact return plus the penalty.

How do the US and Korea avoid double taxation on my salary?

The US taxes citizens and green card holders on worldwide income, so you file in both countries. Korea taxes you as a resident, and the US gives you credit or exclusion for that Korean tax.

You usually pick one of these tools:

• Foreign earned income exclusion (Form 2555): exclude a capped amount of foreign wages if you meet the bona fide residence or physical presence test. See my FEIE guide.
• Foreign tax credit (Form 1116): subtract Korean income tax paid from your US tax, dollar for dollar, within limits.
• Both, in different slices. People often take the exclusion for salary and the credit for other income.

The US-Korea tax treaty keeps the right of the US to tax its citizens, and what treaties mostly do for Americans in Korea is cut withholding on certain income types and provide specific exemptions, such as for visiting professors or students. Read the treaty text or ask a preparer. A subtle point: choosing the 19% flat rate lowers your Korean tax, which can mean a smaller foreign tax credit, but also less tax to credit in the first place.

Americans with Korean bank accounts must also watch US reporting, which is separate from Korean tax. The FBAR guide covers that, and opening a local account is covered in the foreigner bank account guide. US return deadlines for people abroad differ from Korea’s May date, so keep both calendars.

What mistakes cost foreigners the most?

Short list, from the patterns I see most often:

1. Assuming the 183 days start at day 183. The domicile rule can make you a resident from day one.
2. Electing the 19% flat rate without running the regular calculation, or the reverse, ignoring it because it “sounds like a loss.”
3. Missing the May return after a side job, a second employer or a mid-year switch.
4. Leaving Korea without settling. Ask HR to run year-end settlement at your departure date.
5. Forgetting foreign income after year five. Keep your resident-years log.
6. Not claiming treaty relief on paper. The benefit is rarely automatic.

Whatever you decide, keep your passport entry and exit record, your contract, your withholding receipt (원천징수영수증), and a copy of every form you submit. Use HomeTax for filing and the National Tax Service’s English pages for official explanations. If you hold stock, the capital gains guide covers the separate investment side.

This article is general information, not tax or legal advice. Korean rules, the flat-rate cutoff and treaty terms change, and your facts decide the outcome, so confirm current rules with the National Tax Service or a licensed tax professional. Figures are as of October 2026.