How the numbers are made

1. 01

   Constants are sourced and dated

   Tax brackets, wage bases, and deductions come from IRS publications and carry their tax year in the code and on the page. When a year rolls over, the page says so.

2. 02

   Formulas are unit-tested

   Every calculator's engine is a pure function with automated tests against hand-worked examples. The engine that renders on the page is the same one under test.

3. 03

   Your data never leaves the page

   Calculators run entirely in your browser. There is no server receiving your income, no analytics event carrying your inputs.

4. 04

   Corrections are public

   When a number is wrong and gets fixed, the fix is noted on the affected page. Silent edits are for typos, not math.