Capital Gains Tax Calculator

How Capital Gains Tax works

Capital Gains Tax is charged on the profit when you sell or give away something that has gone up in value, such as a second home, a buy-to-let property, shares outside an ISA or a business. It is the gain that is taxed, not the whole amount you sell for.

• Your gain is the sale price, less what you paid and the costs you can deduct: fees for buying and selling (solicitor, estate agent, stamp duty, broker) and the cost of improvements, not repairs or upkeep.
• Everyone has a tax-free allowance, the annual exempt amount, of £3,000 a year. Only gains above it are taxed.
• Gains that fit inside what is left of your basic rate band are taxed at 18%. The rest is taxed at 24%.
• These rates apply to residential property, shares and other assets alike.

How the rate is worked out

Start with your taxable income: your income less your Personal Allowance. The basic rate band is £37,700 of taxable income. Whatever part of it your income has not used is taxed at 18% when filled with gains; anything above is taxed at 24%. If any of your income is already taxed at 40% or more, all your gains are taxed at 24%.

Gain less the £3,000 allowance

£49,600.00

Basic rate band left after your income

£17,700.00

Tax at 18% on £17,700.00

£3,186.00

Tax at 24% on £31,900.00

£7,656.00

Capital Gains Tax

£10,842.00

Losses

• Losses you make in the same tax year come off your gains in full, even if that wastes some of your allowance.
• Losses from earlier years only bring your gains down to the £3,000 allowance. Anything left over carries forward to later years.
• You must report a loss to HMRC within 4 years of the end of the tax year you made it, or you cannot use it.
• A loss on something you sold or gave to a family member or other connected person can only be set against gains on disposals to that same person, so leave those out here.

Business Asset Disposal Relief

If you sell all or part of your business, or shares in a trading company you work for, the gain may qualify for Business Asset Disposal Relief. Qualifying gains are taxed at a single lower rate: 18% in 2026/27, 14% in 2025/26.

• Usually you must have owned the business, or been an employee or officer of the company and held at least 5% of it, for at least 2 years up to the sale.
• There is a lifetime limit of £1,000,000 of qualifying gains. Gains above what is left of your limit are taxed at the normal rates.
• You claim it on your tax return. The calculator does not check whether you qualify.

Reporting and paying

• Selling UK residential property: report and pay the tax within 60 days of completion, using HMRC's Capital Gains Tax on UK property service.
• Other assets: report the gain on your Self Assessment tax return, or through HMRC's real time Capital Gains Tax service (UK residents), by 31 December after the end of the tax year, and pay by 31 January.
• If your total sale proceeds for the year are over £50,000 and you are registered for Self Assessment, you must report them even if no tax is due.

What this calculator does not cover

• Your main home. You usually pay no tax when you sell it, thanks to Private Residence Relief. If you let it out or did not live there the whole time, part of the gain may be taxable.
• More than one sale in a year. Add your gains together and enter the total as one sale if they are all taxed the same way.
• Relief at source pension contributions and Gift Aid, which widen your basic rate band and can lower the tax. The Pension Tax Relief Calculator shows the band effect on Income Tax.
• Gifts to a spouse or civil partner, inherited assets, shares bought at different times (share pooling), EIS and SEIS reliefs, trusts and people who are not UK resident.