Source of record
Every figure this site publishes, the document it came from, the clause inside that document, and the day we read it. If a number here is wrong, this is the page where you find out whose number it was, and the exact sentence we took it from.
Nothing on this page is typed by hand. It is rendered from the same store the calculators read, so it cannot describe a provenance the arithmetic did not actually use. Where a row looks thin, the record is thin.
7 of these 995 rules are verified
Every other row below sits at ingested: read from the primary document by machine, its sentence archived against a content hash, and nothing yet confirming it independently. That is the honest state of this store on 08 September 2026, and we would rather print the number than describe a review process nobody has run.
It matters because ingested is not the same as wrong, and it is not the same as right. It means one reader read one document once. The bar we hold ourselves to, a golden test against the authority’s own worked example, plus a second compiler of the same law agreeing for the same tax year, has been cleared by 7 of them.
The documents, by authority
Grouped by whose document it is, because that is the question a reader actually has: not what our rule is called, but who said so. Open any row to read the sentence we archived, byte for byte, alongside the hash of the copy we hold.
Organisation for Economic Co-operation and Development
OECDThe bulk of the store. Read over the SDMX API rather than from a publication, so the locator is a data key and the archived quote is the CSV row the API returned. Also the second reader every national figure is checked against.
HM Revenue and Customs
GB-HMRCRead from the published rate tables on gov.uk rather than from legislation, because the tables are what HMRC itself directs a taxpayer to. Every locator names the table and the row inside it.
Internal Revenue Service
US-IRSRead from the annual inflation-adjustment revenue procedure rather than from a summary page, because the revenue procedure is the operative document and the summary pages lag it by weeks.
European Central Bank
ECBUsed only where a comparison genuinely requires a common currency. Most comparisons are made at each country’s own average wage, which needs no rate at all and therefore no reading from here.
Financial Crimes Enforcement Network, via IRS
US-FINCENNot a tax authority and not used in any calculation. Held because several guides state a reporting obligation that readers routinely confuse with a tax liability, and a stated obligation needs a source like anything else.
What the statuses mean
Three states, and the distance between them is the whole argument. A status here is not a label we award ourselves for effort; it names exactly how many independent readers have looked at a figure, and a figure cannot move up a level because someone is confident about it.
One reader, once
The figure was read from the primary document by machine and the sentence containing it was archived against a hash, so we can prove what the page said on the day we read it. Nothing has confirmed it independently.
A calculator will use an ingested figure, and the page carrying the result says so rather than implying a review that has not happened.
Two further things are true
A golden test checks our arithmetic against a worked example the authority published itself, and a second body that compiled the same law separately agrees with the figure for the same tax year. Both, for the same rule, or the status does not change.
That second reader is the OECD Tax Database, and it is not a formality. On the day it was connected it disagreed with our UK bands and it was right, which is why the disagreement is in corrections and not in a private branch.
Two readers, and they disagree
The primary document and the second compiler give different answers for the same tax year, and nobody has adjudicated it yet. The figure stays on the page with this status attached rather than disappearing while we work it out.
A disagreement is never resolved by quietly preferring one number. It ends as either a correction or a recorded decision with a name and a date against it, and both of those are public.
Attribution
OECD data is used under the OECD Terms and Conditions, which permit reuse including commercial use, with credit in a format the OECD sets rather than one we choose. Those citations are printed below in full rather than paraphrased, because a paraphrased citation is not a citation.
The same requirement travels with anyone who reuses our open ruleset. If you take the file, you take the acknowledgment with it, and you must impose that same condition on anyone you pass it to. That is not our preference; it is the licence.
The national and central-bank authorities above publish under their own public-sector information terms. Each rule’s source block carries the document, the clause locator and the retrieval date, which is what those terms require us to keep intact.
Found something wrong?
The fastest thing you can send is the official clause you think we misread. Every figure above is downloadable, so a disagreement can usually be settled without either of us guessing at the other’s method. Ruleset sha256:fe993d9d072cbcac.