Bonus Tax in Korea 2026: How a Performance Bonus Is Taxed and What You Take Home

Bonus tax in Korea is simply income tax on extra employment income: your employer withholds tax when the bonus is paid, adds 10% of that tax as local income tax, and the final amount is settled at year-end. This guide is written for foreign employees in Korea, and it covers the same rules Korean colleagues deal with plus the points that trip up expats.

All figures below are as of October 29, 2026. I could not open every official page directly while researching, so rates that came from secondary sources are flagged. Your payroll team and the official sites linked below are the final word.

How does bonus tax in Korea work, and why is the payout smaller than expected?

Your bonus is added to your salary as employment income, taxed on the same progressive scale, and collected in pieces. Income tax and local tax come out on payday, employment insurance usually does too, and health insurance catches up the following spring. That staggered collection is why the number on your bank statement feels low.

The tax authority describes the basic rule on its employment income withholding page: the employer withholds income tax each time it pays salary, bonuses included, using a standard withholding table. The legal basis sits in the Income Tax Act, which you can read at the Korea Law Information Center.

Here is what a bonus passes through, in order.

Step	When	What happens
Withholding	Payday	Employer estimates tax and pays it to the tax office for you
Local income tax	Payday	10% of the income tax, shown as a separate line
Employment insurance	Usually payday	Employee share, reported as 0.9% in 2026
Health insurance true-up	Next spring	Premiums recalculated on the full year’s pay
National pension	From next July	Contribution base updated for the following year
Year-end settlement	Following February	Final tax calculated on all pay, difference refunded or collected

One thing to hold onto: the withholding on payday is a prepayment. It is not your final tax bill.

Is a Korean bonus taxed differently from salary?

The tax rate scale is the same, but the withholding method for bonuses is different, and that is where the odd-looking pay slips come from.

For a bonus tied to a defined period, such as an annual performance bonus, the rule as summarized from the Income Tax Act works like this. Divide the bonus by the number of months in the period. Add that to your average monthly regular pay. Look up the withholding on that combined figure, multiply by the number of months, then subtract the tax already withheld from your regular paychecks. What is left is withheld on bonus day.

For a bonus with no defined period, such as a holiday or spot bonus, the period runs from January 1 to the month it is paid. A bonus paid in December is spread over twelve months in the calculation. One paid in March is spread over three, which can make the annualized income look much larger and the withholding feel heavier.

Neither version changes your final tax. They only decide how much is taken at the moment of payment.

Why the marginal rate matters

Korean income tax is progressive. The published scale starts at 6% on the first ₩14 million of taxable income and rises through 15%, 24%, 35%, 38%, 40% and 42% to 45% at the top. I could not re-verify every threshold against the statute during research, so check the brackets in the Income Tax Act before running your own numbers.

The practical point is that a bonus lands on top of your salary. It is taxed at your marginal rate, not your average rate. If your salary already puts you in the 24% bracket, most of your bonus is taxed at 24% before deductions on the extra income are counted.

What do the four social insurances take from a bonus?

Korea’s “four insurances” are national pension, health insurance with long-term care, employment insurance and industrial accident insurance. Employees pay the first three; the employer pays industrial accident insurance alone.

These employee-side rates for 2026 come from secondary explainers, not from official notices I could open, so treat them as reported.

Insurance	2026 employee share (reported)	How a bonus is treated
National pension	4.75% (9.5% total, split with employer)	Annual income feeds the base, applied each July for a year
Health insurance	3.595% (7.19% total)	Full-year pay is reported by March, premiums settled in April
Long-term care	13.14% of the health premium	Settled together with health insurance
Employment insurance	0.9%	Usually deducted with the bonus; confirm with payroll

Two details deserve attention.

The pension base has an upper limit. Reports indicate the monthly cap moved to about ₩6.59 million from July 2026, up from ₩6.37 million. If your monthly pay including the bonus average is above that, extra income does not raise pension contributions further. The National Pension Service publishes the official figure.

Health insurance is the one that surprises people. Your employer reports the previous year’s total pay, bonus included, to the insurer, and the premium is recalculated. If you received a large bonus last year, expect a bigger April deduction this year. Employer-based health insurance details are on the National Health Insurance Service site.

Foreign employees should also ask HR about pension treatment. Foreign nationals are generally covered, but exemptions or refund rules may apply depending on nationality and on agreements between Korea and your home country. I did not verify country-specific rules, so ask the NPS or your HR team rather than assuming.

What does a ₩10 million bonus look like after tax?

This is an illustration with stated assumptions, not a prediction of your pay slip. Real withholding comes from the official table and your payroll software.

Assumptions

• Single employee, monthly salary ₩5 million (₩60 million a year)
• One lump-sum bonus of ₩10 million
• Taxable income before the bonus around ₩38 million, so the extra income stays in the 15% bracket
• The employment income deduction on additional pay is about 15% (simplified; verify against the statute)
• No change in tax credits because of the bonus

Item	Calculation	Amount
Gross bonus		₩10,000,000
Income tax (estimate)	10,000,000 × 0.85 × 15%	about ₩1,275,000
Local income tax	10% of income tax	about ₩127,500
Employment insurance	0.9%	₩90,000
Cash on payday		about ₩8,507,500 (85%)
Health insurance, next spring	3.595%	about ₩359,500
Long-term care	13.14% of health premium	about ₩47,200
Cash after spring true-up		about ₩8,100,000 (81%)
Pension increase, from next July	4.75%, spread over a year	about ₩475,000

The pension line is not a one-day deduction. It shows up as slightly higher monthly pension contributions after the base resets, and it builds your pension record.

A ₩5 million bonus under the same assumptions leaves about ₩4.25 million on payday and about ₩4.05 million after the health insurance true-up. A bonus large enough to push your taxable income past the next bracket will be taxed at a higher rate on the part that crosses, so do not extend this table to very large amounts.

At roughly 81 cents on the won after the spring adjustment, the bonus is still clearly worth having. It simply arrives in more than one installment of deductions.

How does year-end settlement treat a bonus?

At year-end settlement, your employer adds up everything you earned during the tax year, including every bonus, subtracts your deductions, and recalculates the annual tax. The tax withheld through the year is credited, and the difference is refunded or collected, normally in the February paycheck.

Bonuses matter here in two ways.

Your total pay rises, which raises taxable income. Some deductions only start counting after spending passes a share of your total pay, and a bigger total raises that bar. So in a big-bonus year you can end up with a smaller refund than the year before, even if your spending stayed the same.

Withholding on the bonus may also have been higher or lower than your final liability. Do not treat a hefty withholding line as a lost cost. If your deductions are generous, the surplus comes back at settlement.

Practical steps before year-end:

1. Gather proof for medical, education and donation expenses.
2. Check your pension savings and IRP contributions against the annual limit. The Korea pension savings tax credit guide explains the cap.
3. Confirm your dependents and which spouse claims them.
4. Learn the tax portal before the season starts with the Korea HomeTax guide for foreigners.

If you earn income beyond your salary, you may also need a separate return. The Korea comprehensive income tax guide for expats covers who files in May.

If you leave Korea mid-year, your employer normally settles at your last payroll based on income to that date. Keep that statement for your home-country tax return.

Is the 19% flat tax for foreign workers still available in 2026?

Under the rules in force, foreign workers who start working in Korea by December 31, 2026 can elect a 19% flat rate on employment income, about 20.9% with local income tax, instead of the progressive scale, for up to 20 years from the start of employment. The flat rate generally replaces the deductions and credits you would otherwise claim.

On August 3, 2026, the finance ministry announced a tax reform plan that would raise the flat rate to 21% (about 23.1% with local tax) and extend the deadline to the end of 2029, applying to income from January 1, 2027. These details come from advisory-firm summaries of the plan. As of October 29, 2026, I found no report that the National Assembly has passed it, so treat it as a proposal. Korean tax legislation usually finishes at the end of the year, so look for the final text in December.

Whether the flat rate beats the normal system depends on three things:

• Your total pay. The higher your income, the more likely a flat 19% is lower than your marginal rate.
• Your deductions. If you have many dependents, large medical costs or pension credits, the progressive system can come out ahead.
• Bonus size. A large bonus pushes up your marginal rate, which favors the flat option.

Do not guess. Ask your payroll team to run both calculations for your actual pay, and confirm the election deadline. This is the one choice in the system where a wrong default can cost real money for years.

What mistakes do expats make with bonus tax?

This composite example is invented to show typical errors, not a real person.

An engineer on a ₩70 million salary receives a ₩12 million bonus in December. The pay slip shows a large income tax line, and she assumes she has been over-taxed on the bonus. In February her refund is small, because her total pay rose and her card spending did not clear the higher threshold. In April her salary shrinks by a lump sum, which is the health insurance true-up for last year’s pay. She had not planned for either.

The mistakes behind the surprise were avoidable:

• Treating payday withholding as the final tax.
• Spending the whole bonus before the April and February adjustments.
• Never checking whether the flat rate would have helped her.

A simple habit prevents most of it: when a bonus lands, set aside about 15 to 20 percent as not yet yours. Use the rest freely once spring passes.

What should you do with a bonus after tax?

Move in this order.

1. Park the tax and insurance share in a separate account until the spring true-up and settlement are done.
2. Fill your emergency buffer before spending. Expats without family nearby need a larger one.
3. Use tax-advantaged accounts. The Korea ISA account guide shows what you can and cannot open as a foreign resident, and the pension savings credit rewards contributions before December 31.
4. If you spend overseas often, compare the options in the best credit cards in Korea for expats, because card spending also feeds the deduction thresholds at year-end settlement.
5. Keep your settlement statement and your pay slips together if you will file a return in another country.

A bonus is not a smaller bonus because of tax. It is a bonus paid out over several months of adjustments. Once you know the sequence, payday stops being a shock.

This article is general information, not tax, legal or financial advice. Tax rates, social insurance rates, the pension cap and the foreign worker flat-rate rules can change, and some figures here come from secondary sources. Confirm current rules with the National Tax Service, the National Pension Service, the National Health Insurance Service and your employer’s payroll team before making decisions. Your own situation, including nationality, residency and tax treaties, can change the outcome.