Our calculators and guides are checked against official HMRC and GOV.UK publications. The primary sources we review for 2026/27 Capital Gains Tax figures are listed below. Where a page relies on a specific figure, that source is also linked on the page itself.
Rates, allowances and dates are held once in the calculator code and read from there by every calculator, worked example and paid report, so a change is made in one place. We check them against the sources above when a tax year starts, after a Budget, and when a reader reports a possible error. If a rate changes part-way through a tax year, as it did on 30 October 2024, the code keeps both periods so a sale is taxed at the rate of its own date.
Where a calculation is simplified or an assumption is made, that is stated on the relevant page and explained on the methodology page. All rates reflect the 2026/27 figures unless otherwise noted, and the 18%/24% rates that have applied since the October 2024 Autumn Budget. Our review and update process is set out in our editorial standards.
Reviewed by the UKCapitalGainsTaxCalculator team.
Every figure is checked against current HMRC and GOV.UK guidance and reviewed for the 2026/27 tax year. We explain how the tax works in plain English with worked examples, not just numbers. Editorial standards · Sources · About us