Developer Documentation

Get an API key

Sign up for a free account at /signup. You'll receive a key like ptx_free_... instantly — no credit card required.

Make your first request

Look up tax rates for a California employee on a biweekly pay schedule:

curl "https://payrolltaxapi.com/v1/rates/lookup?workState=CA&payDate=2026-01-01&filingStatus=single&grossWages=5000&payPeriod=biweekly" \
  -H "Authorization: Bearer ptx_free_your_key_here"

You'll get back federal brackets, FICA rates, California income tax brackets, CA SDI, CA SUTA — everything in one response.

Example response

{
  "pay_date": "2026-01-01",
  "work_state": "CA",
  "residence_state": "CA",
  "filing_status": "single",
  "taxes": [
    {
      "tax_type_code": "FED_INCOME_EE",
      "name": "Federal Income Tax",
      "category": "income",
      "taxpayer_side": "employee",
      "jurisdiction": "Federal",
      "rate_structure": "graduated",
      "supplemental_rate": 0.22,
      "wage_base": null,
      "effective_date": "2026-01-01",
      "brackets": [
        { "from": 0,     "to": 11925, "rate": 0.10 },
        { "from": 11925, "to": 48475, "rate": 0.12 },
        { "from": 48475, "to": 103350,"rate": 0.22 }
      ]
    },
    {
      "tax_type_code": "FED_FICA_SS_EE",
      "name": "Social Security (Employee)",
      "category": "fica_social_security",
      "taxpayer_side": "employee",
      "rate_structure": "wage_base_capped",
      "rate": 0.062,
      "wage_base": 176100,
      "effective_date": "2026-01-01"
    },
    {
      "tax_type_code": "FED_FICA_MED_EE",
      "name": "Medicare (Employee)",
      "category": "fica_medicare",
      "rate_structure": "flat_percent",
      "rate": 0.0145,
      "wage_base": null
    },
    {
      "tax_type_code": "CA_INCOME_EE",
      "name": "California State Income Tax",
      "category": "income",
      "jurisdiction": "California",
      "rate_structure": "graduated",
      "supplemental_rate": 0.066,
      "brackets": [...]
    },
    {
      "tax_type_code": "CA_SDI_EE",
      "name": "California SDI (Employee)",
      "category": "sdi",
      "rate_structure": "flat_percent",
      "rate": 0.009,
      "wage_base": null
    }
  ],
  "meta": {
    "tax_count": 8,
    "processing_ms": 12
  }
}