Korea Payroll & Tax API › stamp-duty

South Korea stamp duty (injise) on a contract document by its stated amount

South Korea stamp duty (injise) on a contract document by its stated amount: real-estate ownership transfer contracts and loan agreements, 20,000 to 350,000 KRW, with the exemptions (10M or less; housing transfers up to 100M; loans up to 50M).

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

Input

Field	Type	Required	Description
`amount`	number	yes	Amount stated in the document (KRW)
`document`	real_estate_transfer \| loan		real_estate_transfer (sale contract; default) or loan (money loan agreement)
`housing`	boolean		The property is housing (transfers up to 100M are exempt); default false

Example request

curl -X POST https://api.kkuldogu.com/v1/stamp-duty -H "content-type: application/json" \
  -d '{"amount":500000000,"document":"real_estate_transfer","housing":true}'

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, tax or financial advice. Computed from South Korean statutes and standard formulas as of 2026; reliefs, exemptions and special cases not shown in the result are not modeled, and rules may have changed. Confirm with the relevant office, court, lender or a professional before acting.",
  "source": "https://kkuldogu.com",
  "tool": "stamp-duty",
  "input": {
    "amount": 500000000,
    "document": "real_estate_transfer",
    "housing": true
  },
  "result": {
    "stampDuty": 150000,
    "exempt": false
  }
}

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