Gross vs Net: Why Your Contract Number Is Not Your Bank Number
Every payroll system in the world runs on the same two-number structure: a gross figure that appears in your contract, and a net figure that reaches your bank account after mandatory deductions. The gap between them is what economists call the tax wedge, and it is large everywhere. Across OECD countries, the average single worker loses roughly a quarter to a third of labor cost to income tax and social contributions; Belgium and Germany sit near the top, while Korea's wedge is comparatively moderate — but still very noticeable on a payslip.
In Korea the deductions fall into two families. The four major social insurances (4대보험) — national pension, health insurance with its long-term care surcharge, and employment insurance — are flat-rate contributions on your pay. Then come income tax and its companion local income tax, which are progressive: the rate climbs with income. Both families are withheld by your employer before you ever see the money, which is why the monthly shock is invisible until your first payslip.
A uniquely Korean trap is the 연봉 (annual salary) to monthly conversion. Most contracts divide the annual figure by 12, but some companies historically folded bonuses in and divided by 13 or more, and severance pay (퇴직금) — legally about one month's pay per year of service — is sometimes quoted inside the annual number for contractors, inflating it. Two offers with the same 연봉 can therefore differ by hundreds of thousands of won per month. Before comparing offers, always ask three questions: is severance inside or outside the number, how many installments is it paid in, and how much of the pay is non-taxable allowances.
The Four Major Insurances: Where 9-Plus Percent of Your Pay Goes First
Before any income tax is computed, Korean payroll deducts the employee share of four social insurance programs, and understanding each one demystifies most of the payslip. National pension (국민연금) takes 4.5% from the employee, matched by another 4.5% from the employer, on income up to a monthly cap that is revised each July — earnings above the cap contribute nothing more, which is why high earners see this line flatten. Health insurance (건강보험) takes roughly 3.5% from the employee (matched by the employer), and riding on top of it is long-term care insurance (장기요양보험), calculated not on your salary but as a percentage of the health premium itself — a surcharge on a premium, which is why its line looks oddly small. Employment insurance (고용보험) takes 0.9% for the unemployment benefit fund; the employer pays that plus additional job-stability levies. Industrial accident insurance, the fourth pillar, is employer-paid only, so it never appears on your side of the slip.
Add it up and the employee side comes to roughly 9 to 9.5% of gross pay, with the employer paying a similar or larger amount on top of your salary — the true cost of employing you is about 10% higher than your gross. One caveat matters more than any exact figure: these rates change. Pension reform debates, annual health-insurance rate announcements, and cap adjustments mean the percentages drift almost every year (the health rate alone has crept up repeatedly over the past decade). Treat the numbers here as a snapshot, and check the official 4대보험 portals for the current year before making decisions.
Employee-side rates used by this tool (2026 snapshot;
rates change nearly every year - always verify):
national pension 4.5% of pay (up to monthly cap)
health insurance 3.545% of pay
long-term care 12.95% OF the health premium
employment insurance 0.9% of pay
--------------------------------------------
total ~9.4% of gross (employer pays
a similar amount again on top)
Example, 3,000,000 KRW taxable monthly pay:
pension 135,000
health 106,350
care 13,772 (= 106,350 x 0.1295)
employment 27,000
------------------------
insurances 282,122 (~9.4%) before any income taxWithholding Tables and the Year-End Settlement: How Korean Income Tax Actually Arrives
The income tax line on a Korean payslip is not a live calculation of your true annual tax — it is a lookup. Employers withhold monthly amounts from the 간이세액표 (simplified withholding tax table) published by the National Tax Service, a grid indexed by monthly pay and number of dependents that approximates what someone with your profile will owe over the year. This calculator mirrors that logic in simplified form: it annualizes your pay, applies the earned-income deduction (a formula that shields a large fraction of low and middle wages), subtracts personal exemptions of 1.5 million won per dependent and your pension contributions, runs the result through the progressive brackets from 6% up to 45%, applies the earned-income tax credit and child credits, then divides by 12. Local income tax is then a clean 10% surcharge on the income tax — if you know one, you know the other.
Because the monthly table is only an approximation, Korea reconciles everything each spring in the 연말정산 (year-end tax settlement), where actual deductions — credit-card spending, medical costs, education, housing, donations — replace the table's assumptions. Roughly two thirds of employees get money back; the rest pay in. Employees can even elect to have 80% or 120% of the table amount withheld monthly, trading cash flow now against the size of the settlement later.
The practical reading: your monthly income tax line is a deposit, not a verdict. If it looks slightly different from this calculator, the cause is usually rounding rules in the official table, a different dependent count on file, or company-specific taxable items — not an error in either place.
Non-Taxable Allowances: The 200,000 Won That Punches Above Its Weight
Buried in Korean payroll law is a short list of allowances that are exempt from both income tax and, in most cases, social insurance assessment — and because they escape every rate at once, each exempt won is worth more than a taxable one. The workhorse is the meal allowance (식대), exempt up to 200,000 won per month since the limit was doubled from 100,000 in 2023. Others include a vehicle maintenance allowance up to 200,000 won for employees who use their own car for company business, childcare allowance up to 200,000 won per month for parents of children under six, certain research allowances for R&D staff and teachers, and overtime pay for lower-wage production workers within annual limits.
The arithmetic is what makes this section worth reading. Shifting 200,000 won of a 3,000,000 won salary from taxable base pay into meal allowance does not change gross pay at all, but it removes that slice from pension, health, care, employment, and income-tax bases simultaneously. At a combined marginal bite of roughly 15–25% for a middle-income earner, that is roughly 30,000–50,000 won of extra net pay every month — 360,000 to 600,000 won a year — for a line-item relabel. This is why this calculator asks for your non-taxable amount as a separate input, and why two identical gross salaries can produce different take-home figures.
There are trade-offs worth knowing: a smaller pension base today means slightly smaller pension credits accruing for retirement, and allowances must reflect reality (a meal allowance paired with a company-provided free cafeteria can be challenged in audits). Exemption ceilings are also revised over the years, so verify current limits before restructuring anything.
Same 3,000,000 KRW gross, two structures:
A) all taxable B) 200,000 as meal allowance
taxable base 3,000,000 taxable base 2,800,000
Insurance + tax apply to the taxable base only.
At a combined marginal rate of ~20%:
B saves 200,000 x 0.20 = ~40,000 KRW/month
= ~480,000 KRW/year in extra net pay
Common non-taxable items (limits as of 2026):
meal allowance <= 200,000 /month
own-car business use <= 200,000 /month
childcare (child < 6) <= 200,000 /monthA Full Worked Example — and How Other Countries Do the Same Math
Walk one case end to end. A single employee, gross 3,000,000 won per month, 200,000 of it non-taxable meal allowance, one dependent (self), no children. The taxable base is 2,800,000. The four insurances take about 263,000 won (pension 126,000, health 99,260, long-term care about 12,850, employment 25,200). Income tax from the simplified logic lands in the neighborhood of 30,000 won with the local surcharge adding a tenth of that — modest, because the earned-income deduction and credits absorb most of the liability at this level. Net pay comes out around 2.67 million won, or roughly 89% of gross. The pattern generalizes: around the 3 million mark most of the wedge is social insurance, not tax; push toward 8–10 million and progressive income tax overtakes the insurances as the dominant deduction, with the pension line frozen at the cap.
The same machinery, with different labels, runs everywhere. A US payslip shows FICA (6.2% Social Security under a wage cap plus 1.45% Medicare) alongside federal and state withholding driven by a W-4 form. Japan deducts 社会保険 (health, pension at 9.15% employee share, employment) plus withheld income tax, reconciled by the employer's 年末調整 — the direct ancestor of Korea's year-end settlement. Germany's Lohnsteuer plus roughly 20% employee social contributions produce one of the OECD's largest wedges. The universal lesson holds across all of them: negotiate gross, but budget net.
Finally, keep this page in its lane: it is an educational estimator using a snapshot of rates that change nearly every year, and it cannot see your overtime rules, bonuses, or year-end deductions. For decisions that matter — a job offer, a loan application, a visa income requirement — verify with the official National Tax Service calculators or a licensed tax professional.
Worked example: single, 3,000,000 gross, 200,000 non-taxable
taxable base 2,800,000
national pension 4.5% -126,000
health insurance 3.545% -99,260
long-term care 12.95% of h -12,850
employment ins. 0.9% -25,200
income tax (simplified table) ~-30,000
local income tax 10% of tax ~-3,000
---------------------------------------
net pay ~2,670,000 (~89% of gross)
Same idea, other countries (employee side, approx.):
US FICA 7.65% + federal/state withholding (W-4)
Japan shakai hoken ~14-15% + withheld tax (nenmatsu chosei)
Germany ~20% social + Lohnsteuer
Estimates only - rates change yearly; confirm with the
National Tax Service (hometax) or a licensed tax professional.