Korea's flat tax for foreign workers is going to 21% — and the break-even moves ₩20m

Korea’s finance ministry wants the flat tax rate that foreign employees may elect instead of the progressive scale raised from 19% to 21%, from 2027. It also wants the scheme to run three years longer, covering anyone who first works in Korea by the end of 2029. Both proposals sit in the 2026 tax reform package published on 3 August.

The extension is the generous half and it will get the headlines. The rate is the half that costs money.

Add the local income surtax — a flat 10% of whatever national income tax you owe, paid to your city or province — and the real numbers are 20.9% today and 23.1% from next year. That is a 10.5% larger tax bill at every salary, for every foreign worker on the flat rate. On a ₩200 million package it is ₩4.4 million a year.

What you give up to get the flat rate

Article 18-2 of the Restriction of Special Taxation Act lets a foreign executive or employee apply one rate to Korean-source employment income, for tax years ending within 20 years of the first day they worked in Korea. The income is taxed separately and never lands in the aggregate return. Day labourers are out, and so is anyone whose employer is a related party.

The price is the rest of the code. No employment income deduction — which alone shelters up to ₩20 million. No basic deduction for yourself, a spouse or a dependant. No credit for children, medical bills, tuition, insurance premiums, pension contributions or credit-card spending. Employer-provided housing is the only exclusion that survives.

So the flat rate has always been a high-earner instrument dressed as a convenience. Below a certain salary, electing it is a straightforward mistake, and every year a fresh cohort of arrivals makes it because a recruiter described the 19% as a discount.

The break-even moves about ₩20 million

Korea’s national scale runs from 6% to 45% across eight bands, and the local surtax multiplies each one by 1.1, so the top marginal rate is 49.5%. But marginal is not effective. What matters is where the effective rate on a whole salary — after the employment income deduction — crosses the flat rate.

Future of Korea calculation using the 2026 national bracket table, the 10% local surtax and the employment income deduction schedule. Assumes a single filer with no dependants and no itemised credits, which understates the progressive route slightly.

Add a spouse, two children, a mortgage and a year of orthodontics and the crossover climbs further. Someone at ₩180 million with a full deduction profile can plausibly be better off on the progressive scale at 23.1% while they were better off on the flat rate at 20.9%. This is the practical consequence of two percentage points: not that the tax went up, but that the correct answer changed for a band of people who had already decided.

Nobody appears to be grandfathered

The election is made annually, so there is no locked-in rate to protect. The ministry’s summary places the higher rate from 2027 and describes no carve-out for workers who elected 19% in prior years.

That silence is worth reading carefully, because the same package is explicit about grandfathering elsewhere. Mortgage interest deductions keep the old rules for loans drawn before the end of this year. Performance-fund members who joined by 31 December keep theirs. Where the drafters meant to protect an existing position, they said so.

Why the ministry moved it

The stated reason is arithmetic about Koreans, not about foreigners. When the 19% special rate was introduced, Korea’s top personal rate was 40%. It is 45% now. The gap the flat rate opened has widened by five points without anyone voting to widen it, and officials framed the two-point rise as restoring the intended distance rather than as a tax increase.

That framing also explains why the deadline moved out to 2029 in the same breath. Korea is trying to recruit foreign professionals — the 2026 visa overhaul built a Top-Tier route and an E-7-M track specifically to do it — and withdrawing a headline tax benefit in the middle of that would be an odd signal. Raising the rate while extending the term keeps the recruiting line intact and collects more from the people who use it.

If you are leaving Korea rather than staying, the tax election is the smaller of the two decisions — the National Pension lump-sum refund turns on your nationality and is worth more to most people than two percentage points of income tax.

Figures current as of 26 August 2026, sourced to the ministry release, statute and data portals listed below.