Korea Payroll & Tax API › business-days

South Korea business days

South Korea business days: count working days between two dates, or find the date N business days later, skipping weekends and Korean public holidays (2025-2027 table incl. substitute holidays).

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

Input

Field	Type	Required	Description
`mode`	count \| add		count days between startDate and endDate (default) or add N business days to startDate
`startDate`	string	yes	Start date (YYYY-MM-DD)
`endDate`	string		End date, count mode (YYYY-MM-DD)
`days`	integer		Business days to add, add mode; default 1
`includeStart`	boolean		Count the start date itself, count mode; default true

Example request

curl -X POST https://api.kkuldogu.com/v1/business-days -H "content-type: application/json" \
  -d '{"startDate":"2026-11-10","endDate":"2026-12-31"}'

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": "business-days",
  "input": {
    "startDate": "2026-11-10",
    "endDate": "2026-12-31"
  },
  "result": {
    "businessDays": 37,
    "totalDays": 52,
    "weekendDays": 14,
    "weekdayHolidays": 1,
    "holidays": [
      {
        "date": "2026-12-25",
        "name": "성탄절"
      }
    ]
  }
}

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