How progressive income tax works
Most countries tax income in bands (or "brackets"). You do not pay your top rate on your whole income — only on the portion that falls within each band. This is why your effective rate (total tax ÷ income) is always lower than your marginal rate (the rate on your last dollar earned).
Why the brackets are editable
Tax rates, bands, and allowances differ by country and change most years, so this tool ships with an illustrative schedule that you edit to match your own situation. Enter your local bands and rates, add any tax-free allowance or standard deduction, and the calculator shows your total tax, take-home pay, and the tax due within each band.
Important disclaimer
This is a simplified estimate for education only. It does not account for social security or national insurance contributions, tax credits, local or state taxes, different filing statuses, or capital-gains rules. For anything that matters, check your local tax authority or a qualified accountant.