Methodology & data sources
How the calculators work
Every calculation runs entirely in your browser. Nothing you type is transmitted, stored or logged — there are no accounts and no server-side processing of your numbers.
Paycheck tools use an annual estimator: progressive federal brackets applied to income after the standard deduction, FICA on gross wages, and state tax per each state's model (none, flat, or progressive brackets). This mirrors how major paycheck calculators estimate; it is not the IRS Publication 15-T withholding table, so a real pay stub can differ slightly.
Every tool page shows its formula and a worked example you can check by hand. The figures in those examples are computed by the same engine that powers the calculator above them, so the prose cannot drift from the tool.
Data sources
| Dataset | Primary source | Last verified | Refresh |
|---|---|---|---|
| Federal brackets & standard deduction (2026) | IRS Rev. Proc. 2025-32 | Aug 26, 2026 | Every January |
| Social Security wage base ($184,500) | SSA 2026 wage base announcement | Aug 26, 2026 | Every January |
| State income tax tables | State departments of revenue | Per state, dated on page | Every January |
As further calculators ship, their datasets are added here with the same treatment: mortgage average rates from the Freddie Mac Primary Mortgage Market Survey, and the CPI series behind the inflation tools from the Bureau of Labor Statistics public API.
Verification policy
A figure is either verified against its primary source for the current tax year, or the page says so plainly. There are no silent unverified numbers.
Verified — checked against the state revenue department or IRS publication for tax year 2026, with the check date recorded. 24 of the 25 states we cover are verified today.
Pending verification — carried from prior-year tables. The state page shows a notice, and the comparison table marks the row, until the current-year figure is confirmed. One state is pending today, and 26 more are not modelled at all yet — a state with unconfirmed figures is either shown with this notice or withdrawn until its figures can be checked.
What we deliberately don't model
Local and city income taxes (New York City, Philadelphia, Indiana counties), tax credits such as the Child Tax Credit and EITC, itemised deductions, and state disability and family-leave contributions (SDI/FLI). Each simplification is noted on the pages it affects. If your situation includes any of them, treat results as an upper bound on take-home pay.
Changelog
Material changes to data or method are dated here.
- August 26, 2026 — 2026 federal brackets, standard deductions and FICA limits verified against IRS Rev. Proc. 2025-32; SSA 2026 wage base announcement. The 24 no-tax states confirmed for 2026.
Corrections
If you find a figure that disagrees with a primary source, report it. Confirmed errors are fixed and noted in the changelog above, and affected pages get a fresh last-updated date.
Disclaimer
Estimates are for informational purposes only and do not constitute tax, legal or financial advice. Consult a qualified professional about your own situation.