Capital Gains Tax Calculator United Kingdom

Capital Gains Tax (CGT) is the tax on the profit when you sell or dispose of an asset that has risen in value: shares, cryptocurrency, a second home, a buy-to-let or a business. You are taxed on the gain, not on what you receive. Buy shares for £10,000 and sell them for £30,000, and the £20,000 profit is what counts. This calculator applies the 2026/27 rules, the annual exempt amount, your capital losses and the two rates set against your income, to show what you owe and how much of the gain you keep.

How Capital Gains Tax works

Three things decide your bill: the size of the gain, how much of your annual exempt amount is left and which Income Tax band the gain falls into. CGT is not a flat rate. The taxable gain is stacked on top of your income for the year; the part that fits within your remaining basic rate band is taxed at the lower rate and anything above it at the higher rate. So the same gain can cost a basic rate earner much less than a higher rate earner, and selling in a year when your income is lower can reduce the tax.

The annual exempt amount

Every individual has a CGT annual exempt amount, a slice of gains each tax year that is tax-free. It has been cut sharply in recent years and is £3,000 for 2026/27. It cannot be carried forward, so an allowance you do not use is lost. That makes it worth realising some gains each year, and it is one reason married couples often share assets, so both exempt amounts are used. The calculator deducts the exempt amount automatically; if you have already used it elsewhere this year, tick the advanced option.

Rates for 2026/27

The main CGT rates are the same across most assets. Gains within your unused basic rate band are taxed at 18%, and gains above it at 24%. Residential property that is not your main home, such as a second home or a rental, is taxed at the same rates. Your main home is normally exempt under Private Residence Relief, so it is not included here. Selling all or part of a qualifying business can attract Business Asset Disposal Relief, which taxes the gain at a flat rate up to a £1 million lifetime limit. That rate rose to 18% from 6 April 2026; it still applies even to gains that would otherwise be taxed at 24%. Choose the asset type in the calculator to apply the right treatment.

Losses reduce the bill

If you sell one asset at a loss, the loss is set against your gains before the exempt amount is applied. Losses from earlier years can be carried forward indefinitely, provided you reported them to HMRC, and used against future gains. Enter your allowable losses in the advanced options; the calculator subtracts them first, then applies the exempt amount to what remains. A loss banked in a bad year can shelter a gain in a good one.

A worked example

You make a £20,000 gain on shares and your income for the year is £40,000. After the personal allowance, £27,430 of your income sits in the basic rate band, leaving £10,270 of it unused. Deduct the £3,000 exempt amount and £17,000 of the gain is taxable. The first £10,270 is taxed at 18% (£1,848.60) and the remaining £6,730 at 24% (£1,615.20), so the Capital Gains Tax is £3,463.80. That is an effective rate of just over 17% on the whole gain, and you keep £16,536.20. With income of £60,000 the basic rate band is already full, so all £17,000 is taxed at 24% and the bill is £4,080.

How to use the calculator

Enter the total gain, your annual income before tax and the type of asset. Use the advanced options to add capital losses or to flag that your annual exempt amount is already used. The result shows the Capital Gains Tax due, the taxable gain after the exempt amount, how much of the gain is taxed at each rate, your effective rate and the amount you keep. Use it to decide whether to sell now or wait, to test splitting a disposal across two tax years to use two exempt amounts, or to check a figure before you file.

Assumptions and limitations

This is a planning estimate, not a tax return. It uses 2026/27 rates and the £3,000 annual exempt amount. It assumes you enter the gain already worked out: proceeds minus purchase cost, allowable buying and selling costs and any capital improvements. It does not model Private Residence Relief, letting relief, gifts or transfers between spouses, Investors’ Relief, chattels rules, part-disposals, or pension contributions that extend your basic rate band. Residential property gains must usually be reported and paid within 60 days of completion, separately from Self Assessment. The rates and allowances are stored as parameters sourced from HMRC and reviewed each tax year.

About This Capital Gains Tax Calculator

Use this capital gains tax calculator to get an instant, accurate estimate. The figures follow official GOV.UK guidance and every rate and threshold is kept up to date for 2026. Adjust the inputs above to match your situation, or browse all our calculators to plan your next step.