Developer API

Free, public REST API for global income tax calculations. No authentication required.

Base URL

https://globaltaxcalculator.net/api

Endpoints

GET/api/countries

List all supported countries.

Response

[
  { "name": "Australia", "code": "AU" },
  { "name": "Brazil", "code": "BR" },
  { "name": "Canada", "code": "CA" },
  ...
]

GET/api/countries/:code

Get the full tax data for a country, including all brackets, social contributions, surcharges, and assumptions.

Example

curl https://globaltaxcalculator.net/api/countries/US

Response

{
  "country": "United States",
  "countryCode": "US",
  "taxYear": "2025",
  "currency": "USD",
  "assumptions": {
    "subnationalRegion": "California",
    "notes": [...]
  },
  "incomeTax": {
    "brackets": [...],
    "relief": { "type": "allowance", "amount": 15000, ... }
  },
  "subnationalTaxes": [...],
  "socialContributions": [...],
  "surcharges": [...]
}

GET/api/currencies

List all supported currency codes.

Response

["AED", "ARS", "AUD", "BRL", "CAD", "CHF", "CNY", "EUR", "GBP", "JPY", "USD", ...]

POST/api/calculate

Calculate income tax for one or more countries. Returns a detailed breakdown including income tax, subnational taxes, social contributions, and surcharges.

Request body

Field	Type	Description
`amount`	number	Annual gross income. Must be positive.
`currency`	string	ISO 4217 currency code (e.g. "USD", "EUR", "GBP").
`countries`	string[]?	ISO 3166-1 alpha-2 country codes (e.g. ["US", "GB"]). 1-10 countries. Omit for all.

Example

curl -X POST https://globaltaxcalculator.net/api/calculate \
  -H "Content-Type: application/json" \
  -d '{"amount": 100000, "currency": "USD", "countries": ["US", "GB"]}'

Response

[
  {
    "country": "United States",
    "countryCode": "US",
    "taxYear": "2025",
    "currency": "USD",
    "exchangeRate": 1,
    "gross": 100000,
    "net": 72839,
    "originalGross": 100000,
    "originalNet": 72839,
    "originalTax": 27161,
    "tax": {
      "total": 27161,
      "rate": 0.2716,
      "breakdown": {
        "incomeTax": 14260.5,
        "subnationalTaxes": 5726.96,
        "socialContributions": 7174,
        "surcharges": 0
      }
    },
    "assumptions": { ... },
    "details": { ... }
  }
]

POST/api/tax-curve

Generate effective tax rate curves across an income range for one or more countries. Useful for charting and comparisons.

Request body

Field	Type	Description
`countries`	string[]	ISO country codes. 1-6 countries.
`currency`	string	ISO 4217 currency code.
`maxIncome`	number?	Upper income bound. Default: 300,000.
`steps`	number?	Number of data points (5-50). Default: 20.

Example

curl -X POST https://globaltaxcalculator.net/api/tax-curve \
  -H "Content-Type: application/json" \
  -d '{"countries": ["US", "GB"], "currency": "USD"}'

Response

[
  {
    "country": "United States",
    "countryCode": "US",
    "currency": "USD",
    "points": [
      { "income": 0, "effectiveRate": 0, "netIncome": 0 },
      { "income": 50000, "effectiveRate": 0.2213, "netIncome": 38935 },
      { "income": 100000, "effectiveRate": 0.2716, "netIncome": 72839 },
      ...
    ]
  }
]

Errors

All errors return a JSON object with a status code and message.

{ "statusCode": 404, "statusMessage": "Country not found" }

Code	Meaning
400	Invalid or missing parameters.
404	Country or resource not found.
500	Server error. Try again later.

Attribution

You must include a visible link to globaltaxcalculator.net anywhere you display data from this API. For example:

Tax data by <a href="https://globaltaxcalculator.net">globaltaxcalculator.net</a>

Attribution-free usage is available under a paid license. Contact hello@globaltaxcalculator.net for details.