What is the UK Capital Gains Tax Calculator?
This tool applies to the United Kingdom. Capital Gains Tax (CGT) is charged when you sell or dispose of an asset — such as shares, a second property, or other investments — for more than you paid for it. This calculator estimates the CGT due on your gain after deducting your annual exempt amount. Figures use the 2026/27 rules, where the annual exempt amount is £3,000 and CGT on gains above it is charged at 18% (basic rate) or 24% (higher/additional rate) for both residential property and other assets.
How to use it
Enter your total capital gain for the year, your annual exempt amount (£3,000 for 2026/27), choose whether your taxable income places you in the basic or higher rate band, and select the asset type. The calculator subtracts the exemption, applies the appropriate rate, and shows the tax due and your net gain.
The formula explained
The core calculation is $$\text{CGT} = \max\!\left(0,\ \text{gain} - \text{annual exemption}\right) \times \text{rate}$$ The \(\max(0, \ldots)\) ensures that if your gain is below the exempt amount, no tax is due. The remaining taxable gain is multiplied by your CGT rate. Note that in reality the gain is added on top of your income to determine how much falls into the basic vs higher band; this calculator uses a single chosen band for a quick estimate.
Worked example
Suppose you make a £20,000 gain on shares, with a £3,000 annual exemption, and you are a higher-rate taxpayer. Taxable gain = \(£20{,}000 - £3{,}000 = £17{,}000\). $$\text{CGT} = £17{,}000 \times 24\% = £4{,}080$$ Your net gain after tax is \(£20{,}000 - £4{,}080 = £15{,}920\).
FAQ
Is the annual exempt amount really £3,000? Yes, for the 2026/27 tax year. It was £6,000 in 2023/24 and £12,300 before that, so check the current allowance.
Are property and share rates different? From 30 October 2024 both residential property and other assets share the same rates of 18% and 24%.
Is this an official HMRC figure? No — this is an estimate. Your actual liability depends on your total income, losses brought forward, and reliefs. Consult HMRC or an adviser for confirmation.
