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How we calculate

Every calculator on this site follows the same rules.

One file of rates

All tax bands, fees and thresholds are kept in a single data file, with the source for each figure beside it. Pages read from that file, so a figure is never typed into two places. The current figures are for 2026/27 and were last checked on 25 October 2026.

Tested against worked examples

The calculation code has automated tests built from the examples published by HMRC, Revenue Scotland, the Welsh Revenue Authority and HM Land Registry, and from our own worked examples on each page. A release does not go out if a test fails.

Rounding

• Stamp duty, LBTT and LTT are rounded down to the whole pound, as the tax authorities do.
• Deposit caps are rounded down to the penny, because they are a maximum.
• Other figures are shown to the nearest pound or penny as labelled.

What we don’t do

• We don’t value homes. Bands and tax are worked out from the figures you enter.
• We don’t copy or host EPCs, council tax lists or title registers. We link to the official versions.
• We don’t publish owners’ names or any other personal data.

When figures change

We check rates after each UK Budget, each Scottish and Welsh Budget, and at the start of each tax year on 6 April (1 April for LBTT and LTT). Rules such as the Renters’ Rights Act are checked when each part comes into force. Corrections are listed in the corrections log.