Marginal vs effective tax rate decomposition API

Decompose marginal rate (rate on the last dollar) versus effective rate (total tax / income) over the US 2024 progressive schedule, returning both, the spread, and the per-bracket breakdown so the gap is auditable. Estimate only. Answers 'what's the difference between marginal and effective tax','why is my effective rate lower than my bracket','what's my average tax rate'.

Price$0.01per request

MethodPOST

Route/v1/calc/tax-marginal-vs-effective

StatusLive

MIME typeapplication/json

Rate limit120/minute

CacheNo cache

taxmarginaleffectiveaverage-ratebracketsincome-taxuscalc

API URLhttps://x402.hexl.dev/v1/calc/tax-marginal-vs-effective

Integration docs

Example request

{
  "income": 200000,
  "filingStatus": "single"
}

Example response

{
  "year": 2024,
  "filingStatus": "single",
  "grossIncome": 200000,
  "taxableIncome": 185400,
  "totalTax": 37538.5,
  "marginalRate": 0.24,
  "marginalPercent": 24,
  "effectiveRateOnGross": 0.1877,
  "effectivePercentOnGross": 18.77,
  "effectiveRateOnTaxable": 0.2025,
  "effectivePercentOnTaxable": 20.25,
  "spreadPercent": 5.23,
  "interpretation": "Your next dollar is taxed at 24% (marginal), but your average rate on gross income is 18.77% (effective).",
  "note": "Estimate. Marginal = rate on the last dollar; effective = total tax / income."
}

Input schema

{
  "type": "object",
  "required": [
    "income"
  ],
  "properties": {
    "income": {
      "type": "number",
      "description": "Gross income in USD",
      "examples": [
        200000
      ]
    },
    "filingStatus": {
      "type": "string",
      "enum": [
        "single",
        "married",
        "head"
      ],
      "examples": [
        "single"
      ]
    },
    "deduction": {
      "type": "number",
      "description": "Override deduction in USD"
    }
  }
}

Output schema

{
  "type": "object",
  "additionalProperties": true
}