Tax

State income tax (all 50 states + DC)

Computes state income tax for all 50 states + DC: the nine no-income-tax states ($0), the flat-rate states (single rate), and the graduated states with full brackets and state standard deductions (incl. the CA 1% MHSA and MA 4% millionaire surtaxes, and 0%% floors in ND/SC/DE). Complements the federal tax/estimate engine. v1 covers tax year 2025. Optional pension_income (generic qualified pension/401k/403b/IRA) applies each state's 2025 retirement-income exclusion — full exemption, fixed dollar caps, AGI phase-outs, or NJ/CT tiers — gated by age. Social Security is handled separately. Does not model flat states' own standard deductions. Deterministic.

post/v1/tax/state-income

Request

  • Base URL: https://api.numeratica.com
  • URL: https://api.numeratica.com/v1/tax/state-income
  • Auth: one of:
    • HTTP bearer
    • API key in header X-API-Key

Request body

statestring required

2-letter code or DC. All 50 states + DC covered (2025).

tax_year2025 required
filing_status'single' | 'mfj' | 'mfs' | 'hoh' required
state_taxable_incomenumber required

Non-SS, non-pension income, before the state standard deduction.

social_security_incomenumber

Added to the base only for the 9 states that tax SS; the other 41 + DC exempt it.

pension_incomenumber

Optional. Generic qualified retirement income (private pension / 401k / 403b / traditional IRA). The state's 2025 exclusion is applied; the taxable remainder is added to the base.

ageinteger

Optional. Gates age-conditioned pension exclusions (e.g. GA 62/65, NY 59½, IA 55).

Example request

{
  "state": "CA",
  "tax_year": 2025,
  "filing_status": "single",
  "state_taxable_income": 100000
}

Response

State tax

result_idstring
engine_versionstring
disclaimerstring

Example response

{
  "result_id": "st_1a2b3c4d5e6f7a8b",
  "engine_version": "state-income-1.0.0",
  "inputs": {
    "state": "CA",
    "tax_year": 2025,
    "filing_status": "single",
    "state_taxable_income": 100000
  },
  "result": {
    "state": "California"
  }
}

Changes

No recorded changes to this operation across all 1 revision of this API.