Korea Payroll & Tax API › bonus-tax

South Korea tax withheld on a bonus or incentive payment

South Korea tax withheld on a bonus or incentive payment: income tax by the simplified-table bonus method over the payment period, local tax and employment insurance, and the net bonus.

Price: $0.05 USDC per call over REST (x402 on Base, no API key). MCP: paid-only — the MCP tool returns payment instructions. Basis year: 2026.

Input

Field	Type	Required	Description
`bonus`	number	yes	Bonus amount (KRW)
`monthlySalary`	number	yes	Usual monthly taxable salary (KRW)
`periodMonths`	integer		Months the bonus covers (1, 3 quarterly, 6 half-year, 12 annual); default 1
`dependents`	integer		Dependents including self; default 1
`children8to20`	integer		Children aged 8-20; default 0

Example request

curl -X POST https://api.kkuldogu.com/v1/bonus-tax -H "content-type: application/json" \
  -d '{"bonus":5000000,"monthlySalary":3800000,"periodMonths":12}'

Without payment this returns 402 with x402 payment requirements; an x402 client pays $0.05 USDC and retries.

Example response

{
  "basisYear": 2026,
  "currency": "KRW",
  "disclaimer": "For reference only, not legal or tax advice. Uses official 2026 Korean rates and the same formulas as the kkuldogu.com calculators; actual payroll, NHIS/NPS notices and tax settlement can differ.",
  "source": "https://kkuldogu.com",
  "tool": "bonus-tax",
  "input": {
    "bonus": 5000000,
    "monthlySalary": 3800000,
    "periodMonths": 12
  },
  "result": {
    "net": 4250120,
    "bonus": 5000000,
    "incomeTax": 640800,
    "localIncomeTax": 64080,
    "employmentInsurance": 45000,
    "deductionRatePct": 15
  }
}

For reference only, not legal or tax advice. Uses official 2026 Korean rates and the same formulas as the kkuldogu.com calculators; actual payroll, NHIS/NPS notices and tax settlement can differ. · Calculators for people (Korean): kkuldogu.com · API home · llms.txt · OpenAPI