Enter what you sold an asset for, what you paid and your costs, then your income for the tax year. The calculator deducts your losses and the £3,000 tax-free allowance, works out how much of your basic rate band is left, and charges 18% on the gains within it and 24% above it. The rules are those for individuals in the 2026 to 2027 tax year (6 April 2026 to 5 April 2027), the same in England, Scotland, Wales and Northern Ireland.
Work out your gain
Your gain is usually what you sold the asset for, less what you paid for it and the costs of buying, selling or improving it, such as solicitors’ and estate agents’ fees or an extension (not maintenance). If it was a gift, use its market value when you got it; if you inherited it, use the value used for Inheritance Tax. If you own it jointly, enter only your share of the price and costs.
Losses and the tax-free allowance
Losses made in the same tax year are deducted from your gains in full. The £3,000 annual exempt amount comes next. Losses from earlier years are only used to bring your gains down to that allowance, and anything left over is carried forward. Add any other gains you made since 6 April 2026, so the allowance is shared out correctly.
Which rate you pay
Your taxable income is your income less the Personal Allowance of £12,570, which falls by £1 for every £2 of income over £100,000 and is nil from £125,140. Gains that fit in what is left of the £37,700 basic rate band are taxed at 18%; the rest at 24%. Since 30 October 2024 the same rates apply to residential property and to shares.
Scotland, Wales and Northern Ireland
Capital Gains Tax is a UK-wide tax. Even if you pay Scottish or Welsh Income Tax, the law works out the basic rate band left for your gains as if you did not, so the UK band of £37,700 applies everywhere.
What this calculator leaves out
It assumes no relief: not Private Residence Relief on your home, nor Business Asset Disposal Relief, Investors’ Relief or gift relief. It does not apply the matching rules for shares bought and sold in the same company, and it is not for trustees, personal representatives, companies or people who are not UK resident. Income Tax reliefs, such as pension contributions or Gift Aid donations, can reduce the income that counts: if you have them, the result may overstate your tax.
Rounding and using the result
Each amount is rounded to the nearest penny, with halves rounded up, and the total is the sum of the rounded amounts. Copy the workings in one click, export them as a CSV file or save them to Priostack.
Gain = sale price − purchase price − costs of buying, selling and improving.
Taxable gains = gains − this year’s losses − losses brought forward (down to the allowance) − £3,000.
Basic rate band left = £37,700 − (income − Personal Allowance).
Tax = gains within the band left × 18% + the rest × 24%.
Example: HMRC’s own figures
GOV.UK gives this example for gains made on or after 6 April 2026. With taxable income of £20,000 (an income of £32,570 less the Personal Allowance) and taxable gains of £52,600, the £3,000 allowance leaves £49,600 to tax. The basic rate band has £17,700 left, taxed at 18% (£3,186.00); the other £31,900 is taxed at 24% (£7,656.00). The tax is £10,842.00.
