Auditable, not asserted

The accuracy status page

Golden tests, hundreds of thousands of property checks, and per-page verification dates - the gates every release must pass, in the open.

This page is the working status of the machinery behind the numbers: the checks that run before anything is published, and how fresh the underlying data is. It exists because "we verify our numbers" ought to be a claim someone can audit.

The gates every release must pass

99 golden tests come first. Each one is a paycheck derived by hand from the official schedules, bracket by bracket and cap by cap, that the engine has to reproduce to the cent. One failure stops the whole release.

Then 377,558 property checks sweep salaries, filing statuses and localities across every covered state, hunting for things that must never be true: earning more but netting less, a negative component, tax exceeding gross pay, a 401(k) contribution that somehow raises the total tax. The sweep also probes one dollar either side of every bracket boundary, wage cap and threshold in our specifications, because that is where formulas break.

Last, the build refuses to publish a page carrying an unreplaced template token, a parameter with no source, executable inline script, or an internal editorial note that was never meant for readers.

Where the checking is strongest, and where it is thinnest

The honest shape of it: our tightest evidence is on state tax. For twenty-one states we reproduce every worked example the tax agency publishes, to the cent, and where a third party or an independent derivation has reached our annual figure we say which kind of corroboration it was rather than blend the two.

The local line is the thinner half, and it is worth saying plainly because that line is often as large as the state one. Of the eight states here that levy a city or county tax, four publish worked examples we can replay — twenty-four of them: nineteen from New York, for New York City and Yonkers; one from Indiana, whose Departmental Notice #1 prints the county line of the same worked example as the state line; one from Michigan, for Detroit; and three for the Portland area. Twenty of the twenty-four we reproduce to the cent, and one to within a cent of the agency's own printed rounding. The three Portland figures we reproduce to the dollar, which is the precision their employer handbooks print — those handbooks let an employer round to the dollar or keep the exact cents, so we keep the cents and check the subject-wage figure the handbook publishes on the way. Maryland is a fifth case, and a useful one: its guide contains no worked example at all, but it publishes complete tables whose rate is the state and county rates added together, so we replay all 973 of their cells against the rate schedule the state publishes separately — which anchors the county line and the state line at once. The remaining three have neither, so their local line rests on reading the statute and the forms rather than on reproducing an official calculation. That is exactly where our two largest errors of August 12 were found, and it is why we now state the tax base on each local page rather than only the rate.

What these gates caught recently

On August 12, 2026, the property sweep found that one extra dollar of pay at $40,000 in Ohio leaves you worse off. That is not a defect: Ohio's personal exemption steps down at $40,000 and $80,000, and the law makes the step. We now show it on the page, because a raise that lands just over one of those lines is worth understanding.

The same day, a gate written that morning caught its own author. It replays every figure printed on our pages against the engine. When we later corrected how Ohio's city tax is calculated, the cliff figures we had already published became wrong — they had included a city share that no longer belonged there. The gate refused the build and the page was fixed before it went out.

Less comfortable, and worth recording for that reason: changing Ohio's local tax type made the property sweep stop recognising it, and 8,068 checks silently disappeared behind a reassuring "0 violations". It was caught by comparing the count with the previous run, not by any alarm. The condition is no longer a hand-written list of types.

On their first full run, August 6, 2026, the property checks turned up a genuine defect: a $52 Pennsylvania local services levy was being applied to zero wages. It was corrected the same day.

The same run identified Oregon's phase-out cliffs, which are not a defect at all. Oregon's own formula reduces its federal-tax subtraction in discrete steps, so around $125,000 an extra dollar of income can cost roughly $150 of net pay. We keep the cliffs because the law creates them, and we document them because a reader has every right to know the curve has a hole in it.

Verification freshness, by page

Each calculator page stamps every claim with its source and the date that source was read. Current state of the ledger:

The automated source watch

The project’s own pre-committed bar — the traffic threshold it must meet, and the clocks its machine-readable work runs on — is published on the build-in-public page.

Watched
2026-08-28
146 official URLs under automatic watch. Every source cited in our specifications is re-fetched on a schedule and its text compared with what we read by hand. Nothing is ever republished automatically: a difference raises a flag for a human re-check.

At the run of 2026-08-28T13:37Z: 115 sources confirmed unchanged, 19 unreadable from our servers (16 because the agency's server refuses requests from datacenter IP addresses; 3 because the fetch failed with a network error (SSLError)). A source we cannot fetch is treated as an alarm, never as a pass. Of those 19, 8 open normally from a home connection and are re-read by a tool that records the date; 11 refuse every machine we have and rest on the date their figures were last checked by a person. Separately, 1 document we can download but not read: it carries no text layer, and we watch what it draws.

Each one, with its date
Oldest successful check in the set: 2026-08-23. Cadence: daily cron; each source re-fetched weekly, daily in the Oct-Jan publication window.

12 documents did differ once and are listed below, awaiting the second reading we require before acting on a difference.

The 12 sources that differed once, awaiting a second reading
  • AL — City of Birmingham (rate not read at source) (source)
  • AR — Governor of Arkansas, Bills Signed: HB1001, SB1, 6 May 2026 (source)
  • CO — Colorado FAMLI, official employers page (source)
  • FEDERAL_2026 — SSA, Federal Register 90 FR 49047 (2025-11-03) — the statutorily required offici (source)
  • FEDERAL_2026 — IRS Topic No. 751 (source)
  • FL — Tax Foundation, local income taxes survey (source)
  • MN — MN DOR press release 2025-12-16 (fetched) (source)
  • MO — stlouis-mo.gov + kcmo.gov earnings tax pages (source)
  • OH — The Finder + city pages (source)
  • SC — SCDOR H.4216 information page (source)
  • TX — US DOL UI fact sheet + TWC (twc.texas.gov 403 to our fetcher - search snippets c (source)
  • WA — WA Paid Family & Medical Leave (ESD) (source)
The 19 sources we cannot fetch automatically
  • AZ — Arizona Form 140ES, 2026 Individual Estimated Income Tax Payment, ADOR 10575 (25 (source, blocked_403)
  • AZ — Arizona Form A-4 (2026), ADOR 10121 (25), page 1, box 1; and Employer's Instruct (source, blocked_403)
  • HI — Hawaii Revised Statutes 235-51, schedule introduced by "In the case of any taxab (source, blocked_403)
  • HI — Hawaii Revised Statutes 235-2.4(a)(2)(F), as enacted by Act 46 (2024) (source, blocked_403)
  • HI — Hawaii Revised Statutes 235-54(a) (source, blocked_403)
  • HI — Hawaii Revised Statutes 383-61(a) (source, blocked_403)
  • KY — Louisville Metro Revenue Commission (site unreachable from our network on 2026-0 (source, blocked_403)
  • MO — MO DOR 2026 Withholding Formula (dor.mo.gov geo-blocks; figures cross-read from (source, blocked_403)
  • MO — Missouri Employer's Tax Guide, Form 4282 (2026) (source, blocked_403)
  • NV — Nevada Constitution art. 10 sec. 1(9) (canonical URL) (source, blocked_403)
  • NY — NY PFL official 2026 updates page (source, blocked_403)
  • RI — Rhode Island Division of Taxation, ADV 2025-22, Inflation-adjusted amounts set f (source, blocked_403)
  • RI — 2026 RI-1040ES, page 2, Deduction Worksheet lines 15-22 and Exemption Worksheet (source, blocked_403)
  • RI — Rhode Island Department of Labor and Training, 2026 Tax Rates for Unemployment I (source, blocked_403)
  • RI — State of Rhode Island Division of Taxation, Form RI W-4 (2026) (source, blocked_403)
  • TN — TN DOR GEN-34 (source, blocked_403)
  • MS — MS Pub 89-700-25-1 (Rev. 07/25), Withholding Income Tax Tables and Employer Inst (source, error:SSLError)
  • MS — Mississippi DOR, Individual Income Tax - Tax Rates (source, error:SSLError)
  • MS — MS DOR, Computer Payroll Accounting flowchart, revised 2025-08-13 (read in full) (source, error:SSLError)

The re-verification calendar and the watch list live on the methodology page, and every completed re-verification lands in the changelog. Each calculator page also carries the date its own sources were last re-checked, directly under the paycheck.

The same data, machine-readable

Everything this page vouches for is also published as plain JSON, produced by the same build and held to the same gates: every 2026 rate with its official source and verification date, and the corrections register. No scraping required, no markup to parse.