§ Sources

Sourced to HMRC, end-to-end.

Every tax rate, every threshold, every band in our calculators is taken directly from official HMRC and gov.uk publications. Below are the primary references the engine cites.

When HMRC publishes corrections or new tax-year rates, the engine's rate file is updated and the change is reflected here within seven days. Calculations carry a verified stamp so you can see how recent the data is.

For plain-English explanations of the terms used in the source documents above — IR35, personal allowance taper, marginal relief, dividend allowance, JSL, MVL, BADR, and more — see the glossary. For the calculation logic that turns these rates into numbers, see the methodology.

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