Tax

Taxation of Social Security benefits (§86) + the tax torpedo

The federally taxable portion of Social Security retirement benefits under IRC §86 (the provisional / "combined income" worksheet, IRS Pub. 915): provisional income = other income (AGI excluding SS) + tax-exempt interest + ½ of benefits, taxed in two tiers (up to 50%, then up to 85%) above the statutory base amounts ($25k/$34k single, $32k/$44k joint). Surfaces the "tax torpedo" — the band where each extra dollar of other income also drags $0.50 or $0.85 of benefits into tax, so an optional marginal_ordinary_rate yields the true effective marginal rate (e.g. a 22% bracket becomes 40.7%). The §86 thresholds are statutory and not inflation-indexed, so this engine is not year-keyed. Deterministic; not tax advice.

post/v1/tax/social-security-benefits

Request

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

Request body

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

mfs assumes lived-with-spouse (§86 $0 base); a separated filer should use single.

social_security_benefitsnumber required

Gross annual Social Security benefit.

other_incomenumber required

AGI excluding Social Security (pensions, IRA/401k distributions, wages, gains, etc.).

tax_exempt_interestnumber

Optional. Added back into provisional income under §86(b)(2).

marginal_ordinary_ratenumber

Optional. When set, the response reports the tax-torpedo effective marginal rate on the next dollar of other income.

Example request

{
  "filing_status": "single",
  "social_security_benefits": 24000,
  "other_income": 35000,
  "tax_exempt_interest": 2000,
  "marginal_ordinary_rate": 0.22
}

Response

Taxable Social Security + torpedo metrics

result_idstring
engine_versionstring
disclaimerstring

Example response

{
  "result_id": "sstax_1a2b3c4d5e6f7a8b",
  "engine_version": "ss-tax-1.0.0",
  "inputs": {
    "filing_status": "single",
    "social_security_benefits": 24000,
    "other_income": 35000,
    "tax_exempt_interest": 2000,
    "marginal_ordinary_rate": 0.22
  }
}

Changes

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