South Korea Employer Payroll — 원천징수 & 4대보험

Confirm the employer is registered with the National Tax Service (NTS / 국세청) as a withholding agent and enrolled with all four social insurance agencies (NPS, NHIS, Employment Insurance via 근로복지공단, and Industrial Accident Insurance). Collect employee data needed to compute the correct withholding and insurance amounts.

Calculate each employee's gross monthly pay including base salary, fixed allowances, and any variable pay. Identify tax-exempt allowance components: meal allowances up to KRW 200,000/month (식대), commuting allowances up to KRW 200,000/month (자가운전보조금 for own-car commuters), and child care allowances up to KRW 100,000/month are excluded from taxable wages and from the social insurance base.

Apply NTS withholding to each employee's monthly taxable wage using the 간이세액표 (simplified income tax withholding table), which is indexed by monthly taxable wage and number of dependants (공제대상 가족수 including the employee). The result is the national income tax to withhold; add 10% local income tax (지방소득세) surtax on top. Employees may elect to withhold at 80%, 100%, or 120% of the table amount.

Calculate the employee and employer shares of all four social insurances based on each employee's monthly standard wage (기준소득월액). National Pension (국민연금): 9% total, split 4.5% employee / 4.5% employer, capped at ceiling (KRW 6,370,000/month from July 2025). National Health Insurance (건강보험): 7.09% total, split 3.545% / 3.545%, plus Long-Term Care Insurance (장기요양보험) at 12.95% of the NHIS premium. Employment Insurance (고용보험): 0.9% employee / 0.9%+ employer (varies by firm size). Industrial Accident Insurance (산재보험): 100% employer, rate varies by industry.

File the monthly withholding tax return on Hometax (홈택스) and remit the withheld income tax and local income tax to NTS. For employers with monthly withheld tax under KRW 1,000,000 and fewer than 20 employees who elected the semi-annual filing (반기별 납부), the return and payment are due by the 10th of the month following the semi-annual period instead. Otherwise the deadline is the 10th of the following month.

Remit the combined employee and employer social insurance contributions to each agency by the statutory deadlines: NPS by the 10th of the following month; NHIS (including LTCI) by the 10th of the following month; Employment and Industrial Accident Insurance (combined via 근로복지공단) by the 10th of the following month. The 근로복지공단 issues a monthly invoice (고지서) covering both employment and industrial accident insurance.

Complete the annual income tax settlement in January for the prior calendar year. Each employee submits a deductions and credits claim (소득·세액공제 신고서) supported by certificates gathered through the NTS 연말정산 간소화 서비스 (year-end settlement simplification service, available from 15 January). The employer recomputes the annual tax liability, compares it to total amounts withheld, and either refunds the excess or collects the shortfall in the February payroll. File the 지급명세서 (payment record) with NTS by the end of February.