Korea Payroll & Tax API › loan-repayment

Loan repayment schedule summary as used by South Korean banks

Loan repayment schedule summary as used by South Korean banks: equal monthly payment (wolligeum gyundeung), equal principal (wongeum gyundeung) or interest-only with bullet repayment; monthly payment, first and last installments, total interest.

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
`principal`	number	yes	Loan principal (KRW)
`annualRatePct`	number	yes	Annual interest rate in percent
`months`	integer	yes	Loan term in months
`method`	equal_payment \| equal_principal \| bullet		equal_payment (default), equal_principal, or bullet (interest monthly, principal at maturity)

Example request

curl -X POST https://api.kkuldogu.com/v1/loan-repayment -H "content-type: application/json" \
  -d '{"principal":300000000,"annualRatePct":4.2,"months":360}'

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, 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": "loan-repayment",
  "input": {
    "principal": 300000000,
    "annualRatePct": 4.2,
    "months": 360
  },
  "result": {
    "monthlyPayment": 1467052,
    "firstPayment": {
      "principal": 417052,
      "interest": 1050000,
      "payment": 1467052
    },
    "lastPayment": {
      "principal": 1461588,
      "interest": 5116,
      "payment": 1466704
    },
    "totalInterest": 228138372,
    "totalPayment": 528138372
  }
}

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