Where every number comes from

Primary sources only

Fact-sensitive figures are taken from the agency that publishes them, not from other websites: IRS revenue procedures and newsroom guidance for tax brackets, deductions, contribution limits, and the 2025–2028 car-loan interest deduction; SSA for the wage base and actuarial life tables; the Federal Reserve Survey of Consumer Finances for net-worth percentiles; Census ACS and the World Bank for income percentiles; state revenue departments for all 51 take-home-pay jurisdictions (each state page links its source).

Vintages are visible

Data ages. Where a calculator depends on survey or snapshot data, the page shows the vintage right next to the result — "Federal Reserve SCF 2022," "Census ACS 2023," "SSA 2021 life table" — instead of implying the numbers are live. Currency rates state their snapshot date and that they are not live quotes.

When the honest number is unpopular, it stays

When Congress repealed the federal EV and residential-energy credits in 2025, our defaults moved to $0 and the payback periods got longer — solar's honest default payback went from 9.8 to 13.2 years. Calculators that sell things keep the pretty version; we don't sell things, so we don't have to.

Verified by machines, not vibes

Every engine ships with canonical test vectors — hand-computed expected outputs for known inputs (516 of them, e.g. "a $500,000 IRA at age 73 requires $18,867.92"). A further 469 automated checks load every page in a real browser, type into the inputs, and verify results render and update. All 985 must pass before any change deploys.

Nothing steers the answer

No ads, no affiliate placements, no lead forms, no accounts. All math runs in your browser; inputs are never transmitted. The only measurement is cookieless page-view counting. There is no revenue model attached to what result you get, which is the strongest guarantee we can make about neutrality.

Update cadence & corrections

Tax-year figures are refreshed when the IRS publishes them (typically October–November for the following year). Legislative changes are folded in with the page noting the change, as with the 2025 credit repeals. Found an error? Tell us via the contact on the about page — corrections ship with the same test-vector treatment as everything else.

Reference pages

The datasets behind the calculators, published as citable pages: the IRS Uniform Lifetime Table and the 2026 IRS numbers.