About this site

The tax model is generally built from IRS, Social Security Administration and state revenue or labor publications. Some return comparisons may use a clearly labelled secondary compilation, and a return-based estimate may be used where a current employer-withholding method could not be verified from an accessible publication.

The calculator attempts to model unusual state rules when they are identified and supported by the available material. A rule can still be simplified, misread, transcribed incorrectly or superseded after review, so source links and an explanation of major assumptions are provided where practical.

Automated tests cover selected calculations, data relationships and previously identified errors, and they are run as part of the build process. Selected examples may also be compared with published examples or external calculators.

Those checks can reduce the chance of a regression, but they do not prove that every state, input combination, source interpretation or future rate change is correct. A passing build should not be treated as independent certification of the figures.

Except for selectable Maryland county withholding, the current model generally does not include local income taxes or the full set of return-only credits, itemized deductions and individual exceptions. The available inputs cannot represent every taxpayer or payroll arrangement.

Historical trend extrapolations, where shown, are labelled as arithmetic scenarios rather than official forecasts. Future rates, wages and agency guidance can differ from those scenarios.

HourlyPaycheck is published by Onoir Studio Limited. It is an independent informational site and is not presented as being affiliated with a tax authority or payroll provider.

Corrections and questions can be sent to hello@hourlypaycheck.com. Including the page address, disputed figure and supporting source makes a report easier to review.