UK Tax Guides

Plain-English guides to the rates, thresholds and assumptions behind our calculators. Current guides cite primary HMRC or GOV.UK sources and show when they were reviewed.

Worked examples

Check a complete calculation with its assumptions and official source before trying your own figures.

Official sources

Rates and thresholds are checked against the following primary sources. Review dates are shown on the relevant guide or methodology page.

Last reviewed: 14 August 2026

Guides are general information, not personalised advice. For a calculation, use the relevant tool and verify material decisions with official guidance or a qualified adviser.