Data Methodology & Sources

We publish open datasets on late-payment interest and tax rates. This page explains exactly how every figure is researched, cited, and verified — so you can trust it, and check it yourself against the original source.

51US jurisdictions
(late-payment interest)
42countries & regions
(VAT / GST rates)
Citedevery rate linked to its
statute or tax authority

The principle: every number is checkable

We do not ask you to take our word for it. Every rate in our datasets sits next to a link to its primary source — the controlling statute for US states, or the official government tax-authority page for VAT/GST. If a figure ever looks wrong, that citation is the fastest way to confirm or challenge it. Verifiability, not authority, is the point.

What we publish

Three reference datasets, all released as open data under CC BY 4.0:

  • US state late-payment interest — 51 jurisdictions (50 states + DC). The legal default rate that applies when a B2B contract is silent, the maximum rate a written B2B contract may charge, and the controlling statute for each. It also classifies every state into a three-bucket view of written-contract caps (26 no statutory cap, 12 conditional, 13 hard cap). → reference table & map · CSV · JSON
  • VAT / GST standard rates — 42 countries & regions. The standard rate, a summary of common reduced rates, and the official tax-authority source for each. → VAT/GST guide · calculator · CSV · JSON

Where the numbers come from

We cite the most authoritative source available, in this order:

  1. Primary law or official authority. The statute itself for US states (e.g. Cal. Civ. Code § 3289, Tex. Fin. Code § 302.002), or the government tax authority's own page for VAT/GST (e.g. HMRC, an EU member state's finance ministry, the ATO).
  2. Official secondary — only when the primary page is unreachable. If a statute portal or authority page is down or blocks automated access, we fall back to another official government source that restates the same figure, and we record that in the entry's source note (for example, citing a national business portal when the tax authority's own page returns an error).
  3. Never an uncited aggregator. We do not copy numbers from other rate-listing sites. If we cannot trace a figure to an official source, it does not ship.

How we verify each entry

Two independent passes

Each of the 51 US jurisdictions and 42 VAT regions is first researched against its primary source, then independently re-checked against that same source. Where the two passes disagree, the entry is re-examined against the primary text and corrected before publication.

We cite, we don't paraphrase

The number on the page is the number in the cited source. Each entry also carries a short note recording any nuance a single figure can't capture — a dollar threshold, an exemption, an automatic trigger date, or which official portal we used when the primary page was unreachable.

Definitions, so the data is used correctly

  • Legal (default) rate vs maximum written rate. For late payment these are two different numbers, and we publish both: the default is what state law supplies when the contract is silent; the max written is the ceiling, if any, two businesses may agree to in writing.
  • The three B2B cap buckets. No statutory cap (26 states — any written rate is lawful), conditional (12 — capped, but exemptions usually apply), and hard cap (13 — a firm statutory ceiling).
  • Variable / formula-set entries (9 states). Some states set the default by a formula or a periodically-reset official rate. We do not freeze these to a printed number — we link the live official figure instead.
  • VAT standard vs reduced rates. We publish the standard rate; common reduced rates are summarized, but they vary by item — check the cited authority for specifics.

Updates & last verified

  • US late-payment interest dataset — last verified June 12, 2026.
  • VAT / GST dataset — last verified June 12, 2026.

Both datasets are regenerated from the verified source file at every site build, so the on-page tables, the downloadable CSV/JSON, and the citations never drift apart. When a figure changes at its source, we re-verify against the primary text and date the review.

Limitations — read before you rely on it

Not legal or tax advice. Our datasets are a general reference for business-to-business invoicing. Consumer credit and consumer tax rules are separate and stricter. Statutes and rates change, and courts apply them to specific facts. Always confirm against the linked official source — or a licensed professional in your jurisdiction — before charging, disputing, or filing.

License, citation & downloads

All three datasets are open data under CC BY 4.0 — free to use, share, and cite with attribution. Copy-ready citations sit beside each table, and the raw data is one click away:

Found an error?

We would rather be corrected than wrong. If a figure looks off, tell us with the entry and the official source — we re-check against the primary text and update with a dated note. That loop is exactly why every number ships with its citation.