{"name":"income-tax-api","version":"1.0.0","description":"U.S. federal income tax engine: progressive bracket math (2024 & 2025, all filing statuses), FICA, take-home/paycheck, marginal-rate analysis and long-term capital gains with correct stacking. Deterministic, no DB, no external calls. Statutory brackets. Estimator only — not tax advice; excludes credits, AMT, NIIT and state specifics.","usage":"POST JSON or query params. Default year 2025. filing_status: single | married_jointly | married_separately | head_of_household.","endpoints":{"POST /income-tax":"Gross → taxable → federal tax, marginal + effective rate, per-bracket breakdown","POST /brackets":"Bracket table for year+status, or tax on a given taxable income","POST /fica":"Social Security + Medicare + Additional Medicare from wages","POST /take-home":"Gross → federal + FICA (+ optional flat state) → net, per pay period","POST /marginal":"Marginal rate, next-dollar tax, room left in current bracket","POST /capital-gains":"Long-term capital gains 0/15/20% stacked on ordinary income","GET  /reference":"Full bracket / standard-deduction / FICA / LTCG tables (audit)"},"example":"POST /income-tax {\"gross_income\":100000,\"filing_status\":\"single\"} → taxable 85,000, tax 13,614, marginal 22%, effective 13.61%"}