Tax Bracket API
Progressive (marginal) tax-bracket maths as an API. You supply the bracket schedule, so it works for any country, year or tax table and never goes stale, and it is entirely currency-agnostic. The tax endpoint takes an income and a schedule of threshold:rate pairs (with an optional standard deduction) and returns the total tax, the after-tax income, the effective and marginal rates, and a per-bracket breakdown showing exactly how much is taxed in each tier. The reverse endpoint solves the inverse problem — the gross income needed to take home a target net amount on the same schedule — by bisection. The brackets endpoint validates and normalizes a schedule into labelled tiers (adding a 0% tier from zero and marking the open-ended top bracket). Everything is computed locally and deterministically, so it is instant and private. It models only the schedule you provide — fold any allowances, credits or surtaxes into the brackets or the deduction yourself — and it is not tax advice. Ideal for payroll and HR tools, salary and offer calculators, fintech and budgeting apps, and any product that shows take-home pay. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is progressive-tax maths on a schedule you supply; for gross-pay period conversion use a payroll API and for loans and interest use a finance-calculator API.
api.oanor.com/taxbracket-api
