How we build
Tools that show their work.
Every calculator names the statute or rule it implements, links the primary source, and ships with a unit-test suite on the underlying formula. These are planning tools, not professional advice.
Statute-cited
Every formula maps to a specific statute, rule, or filing — cited inline with a primary-source outbound link so you can verify the source yourself.
Unit-tested
Every formula is a pure function with a regression test suite. The math is deterministic, the inputs are visible, and the tests live in the repo next to the calculator.
Reviewed against statute
Pages carry a visible "last reviewed against" stamp and are refreshed when the statute, rule, or filing changes. These are tools — for binding advice, consult a licensed professional.
100%statute-cited30,319+unit testsOpenformula transparency