Every figure on this site traces to one of the documents below. Each state page also links to its own source directly, so you never have to take our word for where a number came from.
Federal
- IRS annual inflation adjustments — income tax brackets and the standard deduction for each filing status.
- IRS Publication 15-T — federal income tax withholding methods, the tables employers actually use.
- Social Security Administration — the annual contribution and benefit base, which caps Social Security tax.
State
Each of the fifty states and the District of Columbia is checked against its own revenue department. In practice that means one of:
- the employer's withholding guide, usually published as a PDF each January;
- the published rate schedule for the tax year;
- a departmental notice or taxpayer bulletin announcing a change;
- the text of the bill itself, where a change is recent enough that the department has not yet republished.
Each state page names which of these it used and when it was read.
Verification status
Pages carry one of three labels, and we do not round them up:
- Confirmed with the state revenue department — read directly from the state's own document.
- Confirmed by two independent tax sources — two professional sources agree, and a departmental check is scheduled.
- Primary check pending — the figure comes from an aggregated national table and has not yet been confirmed at source. Shown in amber, because you deserve to know.