Korea Payroll & Tax API › freelancer-withholding

South Korea 3

South Korea 3.3% business-income withholding for freelancers (3% income tax + 0.3% local tax), in either direction: net from gross, or the gross to invoice for a target net.

Price: $0.01 USDC per call over REST (x402 on Base, no API key). MCP: free as freelancer_withholding at https://api.kkuldogu.com/mcp. Basis year: 2026.

Input

Field	Type	Required	Description
`amount`	number	yes	Gross payment, or desired net when direction is net_to_gross (KRW)
`direction`	gross_to_net \| net_to_gross		default gross_to_net

Example request

curl -X POST https://api.kkuldogu.com/v1/freelancer-withholding -H "content-type: application/json" \
  -d '{"amount":1000000}'

Without payment this returns 402 with x402 payment requirements; an x402 client pays $0.01 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": "freelancer-withholding",
  "input": {
    "amount": 1000000
  },
  "result": {
    "gross": 1000000,
    "incomeTax": 30000,
    "localIncomeTax": 3000,
    "net": 967000
  }
}

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