Income Tax Calculator API

About the Income Tax Calculator API

An income tax API for US federal tax calculation, built for apps that need to calculate taxes from a salary. Income Tax Calculator works by applying the official federal income tax brackets to your gross income after the standard deduction. It calculates the tax owed at each bracket level and returns a detailed breakdown including effective and marginal tax rates. Add fica=true to get take-home pay after the employee share of Social Security (capped at that year's wage base) and Medicare, including the 0.9% Additional Medicare Tax, with the FICA amounts themselves itemized on paid plans.

What people use it for

Job Offer Evaluation

When weighing multiple job offers, candidate compensation portals calculate net take-home pay and federal tax obligations across different filing statuses.

Payroll Withholding Estimation

HR platforms estimate employee annual federal tax liability and monthly deductions directly from gross salary inputs to forecast withholdings.

Retirement Distribution Modeling

To model retirement drawdowns, financial advisors project changes in effective and marginal rates as client taxable distributions shift across tax bands.

Custom Rate Invoicing

Compute estimated tax obligations and remaining net earnings for freelance contracts using custom tax percentages and project deductions.

Without writing code

Income tax and refund calculator on DigestYourFinances estimates your federal tax and refund.

Ways to call it

One endpoint, many ways in — REST with JSON, XML, YAML and CSV, plus GraphQL and an MCP interface for AI agents.

JSON

Default REST response

XML

Markup format

YAML

Human-readable

CSV

Tabular export

Beta

GraphQL

Query language

New

MCP

For AI agents

Request parameters — GET /v1/incometaxcalculator

Sent in the query string. Premium parameters are accepted on every plan but only take effect on plans that include them. Anything not listed here is dropped rather than passed through.

Required

Optional

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curl "https://api.apiverve.com/v1/incometaxcalculator?income=85000&rate=22&deduction=14600" \
  -H "x-api-key: YOUR_API_KEY"

Authentication

Send your key in the x-api-key header. That is the only auth step — no token exchange, and no per-endpoint scope to configure.

Response — GET /v1/incometaxcalculator

Every APIVerve endpoint returns the same three top-level keys, so one response handler covers your whole integration: status, error and data. Only data changes shape.

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{
  "status": "ok",
  "error": null,
  "data": {
    "year": 2025,
    "filing_status": "single",
    "income": 85000,
    "standardDeduction": 15000,
    "taxableIncome": 70000,
    "totalTax": 10313.88,
    "effectiveRate": "12.13%",
    "marginalRate": "22%",
    "incomeAfterTax": 74686.12,
    "monthlyTax": 859.49,
    "monthlyIncome": 6223.84,
    "brackets": [
      {
        "rate": 0.1,
        "ratePercent": "10.0%",
        "rangeMin": 0,
        "rangeMax": 11925,
        "taxableAmount": 11926,
        "taxAmount": 1192.6
      },
      {
        "rate": 0.12,
        "ratePercent": "12.0%",
        "rangeMin": 11926,
        "rangeMax": 48475,
        "taxableAmount": 36550,
        "taxAmount": 4386
      },
      {
        "rate": 0.22,
        "ratePercent": "22.0%",
        "rangeMin": 48476,
        "rangeMax": 103350,
        "taxableAmount": 21524,
        "taxAmount": 4735.28
      }
    ],
    "fica": {
      "total": 6502.5,
      "socialSecurityRate": 0.062,
      "socialSecurityWageBase": 176100,
      "socialSecurityTax": 5270,
      "medicareRate": 0.0145,
      "medicareTax": 1232.5,
      "additionalMedicareThreshold": 200000,
      "additionalMedicareTax": 0
    },
    "takeHomePay": 68183.62,
    "monthlyTakeHomePay": 5681.97,
    "totalEffectiveRate": "19.78%"
  }
}

Response fields

Paths are relative to data. Premium fields are absent rather than zeroed on plans that do not include them, so check for presence instead of comparing to 0.

Response headers

Every response carries your balance, so your own code always knows where it stands without polling anything. All four are exposed to browsers through CORS.

Errors

Read the HTTP status first, then error for the specific reason. The body names the parameter that has to change.

What a call costs — 2 credits per call

Credits are shared across every APIVerve API — one balance, one key, one bill. Failed requests never count against it, so a rejected input costs nothing.

Calls are what the credits buy at this API's rate — spend them here, on any of the other APIs, or across both. Nothing is reserved per endpoint.

Zero-code embed — one snippet, no backend

Drop an interactive Income Tax Calculator form onto any page. The widget calls the API for you, so no key ever appears in your markup and there is nothing to deploy.

Changelog — Income Tax Calculator API

Every change to this endpoint, newest first. Breaking changes ship as a new version and the previous one keeps serving — response fields are added, never removed or retyped in place, so an integration written against v1 keeps working.

Currently v1