Because Korean payroll takes two bites before your bank account sees anything: the four social insurances (4대보험), which cost an employee roughly 9.7% of gross pay in 2026, plus income tax and a 10% surtax on it. A ₩4,000,000 contract (roughly $2,700 at mid-2026 rates) usually lands in the mid-₩3-millions.
I want to tell you how I ended up caring about this, because it was not an act of curiosity. It was an accusation.
My January payslip was smaller than my December one. Not by much. But my annual raise had just landed, so it should have gone the other way, and I build internal systems at a Korean financial company for a living, which means my reflex when a number moves in the wrong direction is not “huh, interesting” — it is “something is broken and I am going to find it.” I opened the payslip PDF next to December’s and started diffing line items like a bug report.
There was no bug. There was a rate change. Two, actually, landing in the same month, and one of them was the first time the National Pension rate had moved since 1998 — a number that had sat flat for my entire working life and most of my schooling. Then in July the pension contribution ceiling moved again.
A while back I wrote about what our household of three actually spends in a month. That post starts at the take-home number and spends it. This is the prequel nobody writes: how the number on your contract becomes the number in your bank app.
Why is my Korean paycheck smaller than my contract salary?
Your contract almost certainly quotes gross annual or monthly pay. What arrives is 실수령액 (silsuryeongaek, literally “the amount actually received”), and the gap between the two is not negotiable, not a mistake, and not something your employer chose. Korea collects social insurance and income tax by 원천징수 (woncheon jingsu, literally “collection at the source”), meaning your company is legally required to withhold it and hand it over before paying you the rest.
So the order of operations on a Korean payslip goes like this. Gross pay comes in. The four insurances come out first, as fixed percentages. Income tax comes out next, as an amount looked up in a government table. A local surtax equal to 10% of that income tax comes out after it. Whatever survives is yours.
The percentages are public and identical for everyone, foreigner or Korean, which is why you can predict the insurance part of your payslip to the won before you sign anything. The tax part is the one that surprises people, and I will get to why.
What are the “four insurances” (4대보험) on every Korean payslip?
4대보험 (sa-dae boheom, “the four major insurances”) is the bundle every salaried worker in Korea is enrolled in from day one of employment. Koreans say the phrase the way Americans say “benefits,” except it is not a perk and you cannot decline it. Here is what each one is. And the part that genuinely surprises foreign readers: how little of the headline rate you personally pay.
| Insurance | 2026 rate | You pay | Employer pays |
|---|---|---|---|
| National Pension 국민연금 |
9.5% of standard monthly income | 4.75% | 4.75% |
| Health Insurance 건강보험 |
7.19% of income | 3.595% | 3.595% |
| Long-Term Care 장기요양보험 |
0.9448% of income (= 13.14% of your health premium) |
about 0.4724% | about 0.4724% |
| Employment Insurance 고용보험 |
1.8% (unemployment benefit portion) | 0.9% | 0.9%, plus a job-security/skills portion of 0.25%–0.85% paid entirely by the employer |
| Industrial Accident 산재보험 |
rated by industry | nothing | 100% |
Two names in that table carry most of the weight. 국민연금 (gungmin yeongeum, National Pension) and 건강보험 (geongang boheom, National Health Insurance) are together more than four-fifths of everything that leaves your paycheck, and they are the two that moved this year. But the other two are worth pulling out, because they are the ones you never think about. 산재보험 (sanjae boheom, Industrial Accident Compensation Insurance) is one of the four and it costs you exactly zero. The employer carries all of it, priced by how dangerous your industry is. And 고용보험 (goyong boheom, Employment Insurance) has a second layer your employer pays alone, on top of the 0.9% you both put in. So of the four insurances that make your paycheck smaller, one does not touch you at all and another only half-touches you.
장기요양보험 (janggi-yoyang boheom, Long-Term Care Insurance) is the line that makes people squint. It funds care for the elderly, and it is calculated as a percentage of your health insurance premium, not of your salary, which is why your payslip prints it as a separate line right under health insurance and why the number looks so oddly small. Both ways of quoting it describe the same money.
Add the employee-side rates up — 4.75 + 3.595 + 0.4724 + 0.9 — and you land at about 9.72% of gross pay. That is my arithmetic on the four published rates, not an official statistic, but it is the number that actually leaves your account.
Why did my January paycheck shrink after a raise?
Because all of those rates moved at once, and 2026 is the year Korean payslips visibly changed.
The National Pension rate went from 9% to 9.5% on January 1, 2026, split 50/50, so the employee side went 4.5% → 4.75%. That is the first change since 1998. To put a face on it, the government’s own example is a worker earning the average ₩3.09 million a month, who now pays about ₩7,700 more per month. It is scheduled to keep climbing 0.5 percentage points a year until it reaches 13% by 2033. In exchange, the income replacement rate rose from 41.5% to 43% — you are paying more and the pension you eventually collect is worth slightly more.
Health insurance went from 7.09% to 7.19%, a 0.1 percentage point bump decided in August 2025. The ministry’s own figure: the average employee-borne health premium goes from ₩158,464 to ₩160,699 a month. Long-term care rode along, from 0.9182% to 0.9448% of income. Employment insurance did not move.
Three of the four, in one month, on top of a raise that was supposed to make the number bigger. Here is what it looks like on a ₩4,000,000 monthly salary — an illustrative calculation from the published rates, rounded to the nearest hundred won, since the pension and health services apply their own rounding rules and a real payslip can land a few won either side.
| Deduction on ₩4,000,000 gross | 2025 | 2026 | Change |
|---|---|---|---|
| National Pension | ₩180,000 | ₩190,000 | +₩10,000 |
| Health Insurance | ₩141,800 | ₩143,800 | +₩2,000 |
| Long-Term Care | about ₩18,400 | about ₩18,900 | +about ₩500 |
| Employment Insurance | ₩36,000 | ₩36,000 | — |
| Four insurances, total | about ₩376,200 | about ₩388,700 | +about ₩12,500 |
| Income tax + 10% local surtax | Set by the withholding table — depends on your dependents (see below) | ||
So on an unchanged ₩4M salary, the 2026 rate changes cost about ₩12,500 a month, roughly ₩150,000 over a year. The four insurances together now take about ₩388,700 (roughly $260 at mid-2026 rates) out of that salary every month, and that is before the tax lines start. My raise was real. It just had to clear a hurdle first, and in January it did not clear it by enough.
One more thing moved, and it moved this month. Pension contributions are charged only on your 기준소득월액 (gijun sodeuk woraek, the standard monthly income used as the contribution base), which sits inside a band with a floor and a ceiling. From July 2026 that ceiling rises from ₩6.37 million to ₩6.59 million a month and the floor from ₩400,000 to ₩410,000, holding until June 2027. If you earn above the ceiling, you are not charged on the excess — your pension deduction simply stops growing. High earners will see one more small step up in their July payslip and then nothing.
How much income tax is taken out each month?
This is where I have to disappoint anyone hoping for a percentage.
Monthly income tax in Korea is not a formula. It is a lookup. The National Tax Service publishes the 간이세액표 (ganiseaekpyo, the Simplified Tax Withholding Table), and your payroll team finds the cell where your salary level meets your number of dependents, and that cell is your tax. Two colleagues on identical salaries can have visibly different tax lines because one has two kids and the other has none. Any blog that tells you “income tax is about X% of a ₩4M salary” is guessing, and the guess breaks the moment your family situation does not match the writer’s.
On top of that comes 지방소득세 (jibang sodeukse, local income tax), which is fixed and simple: exactly 10% of the income tax that was just withheld. Not 10% of your salary. Ten percent of the tax. It shows up as its own line and everyone ignores it until they add up the deductions and find one they cannot account for.
You can also choose to have 80%, 100% or 120% of the table amount withheld. Pick 120% and you overpay every month and get more back in the spring; pick 80% and you keep more now and may owe in the spring. Most people never touch this setting and stay at 100%. If you want your real number rather than an internet guess, run your salary and dependents through the NTS withholding calculator on Hometax — it is the same table your payroll runs.
Do foreigners have to pay all of this too?
Yes. All four insurances, income tax, local surtax, on the same terms as your Korean colleagues. There is no expat exemption and no version of the Korean payslip where the deductions are optional.
But there is one detail I got wrong out loud, and I would rather you hear it from me than repeat it. When someone from our overseas team was moving to the Seoul office, I passed along something I had picked up in an English-language forum: that health insurance kicks in after six months of residence. Our HR lead corrected me, politely, in front of him. The six-month rule is real, but it applies to people who live in Korea without a job. They become mandatory 지역가입자 (jiyeok gaipja, regional subscribers) the day after the six-month mark, though some visas — students, F-5 permanent residents, F-6 marriage migrants, E-9 workers — are enrolled the moment they register as foreign residents. If you have an employment contract, you are a 직장가입자 (jikjang gaipja, workplace subscriber) from your first day of work. No waiting period. Your card works immediately.
Where six months does bite is other dependents. Your spouse and your children under 19 are exempt: they can go on your workplace coverage as soon as they land. But a parent, or a child aged 19 or over, generally needs six months of residence in Korea before you can add them. That is the gap that catches families bringing a grandparent along, and it is worth knowing before you get on the plane rather than at a hospital counter afterward.
Can foreigners choose the 19% flat tax instead?
You can, and this is the one genuine fork in the road that Koreans do not have. Under Article 18-2 of the Restriction of Special Taxation Act, a foreign employee may elect to have employment income taxed at a flat 19% instead of Korea’s progressive brackets. It applies to tax years ending within 20 years of the day you first provided labor in Korea. As the law currently stands, you must have first started working in Korea on or before December 31, 2026 to be eligible at all — and I would watch that date, because Korea’s tax revision bill lands each summer and this deadline has been pushed before.
Now the catch nobody puts in the headline. Elect the flat rate and you give up almost everything else: non-taxation, deductions, exemptions and tax credits stop applying to you (a narrow carve-out exists for certain welfare-type benefits). And the flat 19% still carries the 10% local surtax, so your real rate is about 20.9%, not 19%.
Which means the flat tax is not a discount. It is a bet, and it only pays off if you earn enough that the progressive brackets would have taken more than 20.9% of your income and you have few deductions to lose — no mortgage interest, no dependents, no big medical or education spending. For a mid-salary teacher with a family, electing it can easily cost money. Run both calculations before you sign the election form. If the numbers are close, the deductions you would be surrendering are usually the tiebreaker.
Can I get my pension money back when I leave Korea?
Often, yes — through the 반환일시금 (banhwan ilsigeum, literally “returned lump sum”), which pays back your National Pension contributions plus interest when you leave the country for good. Whether you qualify comes down to three routes, and you need only one of them.
- A social security agreement. Your country has a benefit-covering agreement with Korea. The National Pension Service lists countries including the USA, Canada, Germany, France, Australia, India and the Philippines.
- Reciprocity. Your country grants an equivalent benefit to Korean nationals. NPS maintains this list too, and it includes countries such as Thailand, Indonesia, Malaysia and Sri Lanka.
- Your visa. If the insured period was worked on an E-8, E-9 or H-2 visa, you qualify regardless of nationality.
I am deliberately not printing the full country lists here, and you should be suspicious of any blog that does. These lists are maintained by NPS, they change, and the difference between a stale copy-paste and the real list is potentially years of your contributions. Check your own nationality against the current NPS list, or call the NPS foreign-language line before you book your flight. The claim is normally made as you depart, and the money is wired to your overseas account — but the paperwork is far easier to start while you are still here with a bank account and an alien registration card that works.
What is 연말정산, the “13th month’s salary”?
Every February, Korean group chats fill up with people either gloating or complaining, and the reason is 연말정산 (yeonmal jeongsan, the year-end tax settlement). All year your employer has been withholding tax from that simplified table, which is an estimate. In January and February you file the real numbers — credit card spending, rent, insurance, medical bills, donations, dependents — and the tax office settles the difference.
Overpay across the year and you get a refund, which Koreans call 13월의 월급 (sipsam-worui wolgeup, “the 13th month’s salary”). Underpay and you owe, and the phrase you hear instead is 세금 폭탄 (segeum poktan, a “tax bomb”). Same process, two very different Februaries.
Foreign employees do this too, and it is where the flat-tax choice comes home to roost: if you elected 19%, most of those deductions you spend February collecting receipts for simply do not apply to you. It is also the single most valuable hour a foreign worker in Korea can spend on their own money, and the one most people skip because the Hometax interface is intimidating and the deadline lands right when nobody wants to think about paperwork.
What I’d tell you if you were signing a Korean contract tomorrow
Take the gross monthly figure, cut about 9.7% for the four insurances, then cut income tax and its 10% surtax on top of that, and be pleasantly surprised rather than blindsided. For a ₩4,000,000 contract that means budgeting from the mid-₩3-millions, not from four.
And know that the trend line only goes one way. The pension rate is legislated to climb half a point a year to 13% by 2033, so the payslip shock I had in January is not a one-time event — it is an annual appointment I have now scheduled a calendar reminder for, mostly so I stop trying to debug my own payroll.
The one thing I would not do is take a stranger’s percentage as gospel, mine included. The insurance rates are public and fixed, so those you can trust. The tax line is decided by a table and your own family situation, and the pension refund is decided by your passport. Look up your own two numbers. They are the only ones that will show up in your account.
I build systems at a financial company; I am not a tax adviser. This is a map of how the deductions work, not advice on your particular return — for that, use the NTS calculators or talk to a Korean tax accountant (세무사, semusa).