Korea Payroll & Tax API › financial-income-tax

South Korea comprehensive taxation of financial income (interest and dividends over 20 million KRW a year)

South Korea comprehensive taxation of financial income (interest and dividends over 20 million KRW a year): compares the comprehensive method (first 20M at 14%, the excess added to other income at 6-45%) with the 14% separate method and takes the larger, then shows tax due beyond what was withheld. Dividend gross-up and the 2026 high-dividend separate-taxation option are not modeled.

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
`financialIncome`	number	yes	Total interest and dividend income for the year, before tax (KRW)
`otherTaxBase`	number		Tax base of other comprehensive income (after deductions), e.g. wage or business income; default 0 (KRW)

Example request

curl -X POST https://api.kkuldogu.com/v1/financial-income-tax -H "content-type: application/json" \
  -d '{"financialIncome":50000000,"otherTaxBase":50000000}'

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": "financial-income-tax",
  "input": {
    "financialIncome": 50000000,
    "otherTaxBase": 50000000
  },
  "result": {
    "comprehensiveTaxation": true,
    "totalIncomeTax": 16240000,
    "method": "comprehensive",
    "comprehensiveMethodTax": 16240000,
    "separateMethodTax": 13240000,
    "taxOnOtherIncomeAlone": 6240000,
    "withheldOnFinancialIncome": 7000000,
    "additionalIncomeTaxDue": 3000000,
    "additionalLocalIncomeTax": 300000
  }
}

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