Capital Gains Tax Calculator

Everyone gets an Annual Exempt Amount of £3,000 in 2026/27 — the first £3,000 of your total gains each tax year is free of Capital Gains Tax. It can’t be carried forward: if you don’t use it, you lose it. Couples each have their own allowance, so jointly owned assets can shelter up to £6,000 of gains between them.

Your taxable gain is stacked on top of your taxable income. Any part that fits inside your unused basic-rate band (income up to £50,270 in 2026/27) is taxed at 18%; anything above that is taxed at 24%. That’s why the calculator asks for your income — the more you earn, the more of your gain is pushed into the 24% band. Higher and additional-rate taxpayers pay 24% on the whole taxable gain.

If you sell a UK residential property at a gain — for example a buy-to-let or second home — you must report the disposal and pay the CGT within 60 days of completion, using HMRC’s “report and pay CGT on UK property” service. This is separate from (and earlier than) your Self Assessment return, though the disposal still goes on the return too. Your main home is usually exempt under Private Residence Relief.

Business Asset Disposal Relief (formerly Entrepreneurs’ Relief) gives a reduced flat CGT rate when you sell all or part of a qualifying business — for example a sole-trade business or shares in your personal trading company. From 6 April 2026 the rate is a flat 18%, and there is a £1 million lifetime limit on gains that can qualify. Qualifying conditions (like the two-year ownership rule) apply, so check before you rely on it.

Capital losses in the same year are deducted from your gains before the Annual Exempt Amount, and unused losses can be carried forward — enter your gain net of any losses. The calculator gives an estimate only: it doesn’t model Private Residence Relief, the £1m BADR lifetime limit, trusts, non-resident rules or carried-interest rates, and it isn’t financial advice. Speak to a qualified accountant about your own position.