UK Capital Gains Tax Calculator

How UK Capital Gains Tax works

What is Capital Gains Tax and when does it apply?

Capital Gains Tax (CGT) is a tax on the profit (the "gain") you make when you sell or dispose of an asset that has increased in value. It's the gain that is taxed, not the total amount you receive.

CGT applies to a wide range of assets, including shares and funds held outside an ISA, investment property (buy-to-let and second homes), cryptocurrency, valuable personal possessions worth more than £6,000, and business assets. It does not generally apply to your main home (covered by Private Residence Relief), assets held inside an ISA or pension, or personal cars.

A "disposal" includes selling the asset, gifting it to someone other than a spouse or civil partner, swapping it for something else, or receiving compensation for it being damaged or destroyed.

The annual exempt amount

Each tax year, every individual gets a CGT annual exempt amount — £3,000 in 2026/27. Any gains up to this threshold are tax-free. If you have multiple disposals in a year, you can apply the exempt amount to reduce your combined net gains.

The exempt amount cannot be carried forward — if you don't use it, you lose it. This makes it worth considering whether to take gains across two tax years if you're close to the threshold. Married couples and civil partners each get their own exempt amount, which can effectively double the tax-free allowance on jointly held assets.

How your income affects your CGT rate

Unlike income tax, CGT is charged at just two rates depending on your total income in the same tax year:

• 18% — for gains (or the portion of gains) that fall within the basic rate income tax band (up to £50,270 combined income + gain for 2026/27)
• 24% — for gains (or the portion) above £50,270

Crucially, your gain is stacked on top of your income for rate purposes. So if you earn £45,000 and have a £20,000 taxable gain, the first £5,270 of the gain sits in the basic rate band (taxed at 18%) and the remaining £14,730 sits in the higher rate band (taxed at 24%). This calculator handles that split automatically.

Note: the same 18%/24% rates now apply to both standard assets and residential property following the 2024 Autumn Budget changes, which aligned property CGT rates with other asset rates.

Business Asset Disposal Relief (BADR)

BADR (previously called Entrepreneurs' Relief) reduces the CGT rate on qualifying business disposals to a flat 18%, regardless of your income level. It applies to:

• All or part of a trading business you own
• Shares in your own company (if you hold at least 5% of shares and voting rights)
• Assets used in your business when the business closes

There is a lifetime limit of £1 million of qualifying gains at the 18% BADR rate. Any gains above the lifetime limit are charged at standard CGT rates. You must also have owned the business or shares for at least two years before the disposal. BADR conditions are complex — always take professional advice before a business sale.

How to report and pay Capital Gains Tax

There are two ways to report CGT depending on the type of asset:

• Residential property: if you sell a UK residential property (that isn't your main home), you must report and pay any CGT within 60 days of completion using HMRC's online "Report and Pay CGT on UK Property" service. This is separate from Self Assessment.
• All other assets: report CGT via your Self Assessment tax return for the relevant tax year. The tax is due by 31 January following the end of the tax year.

If your total gains are below the annual exempt amount, you generally don't need to report. But if your total proceeds exceed four times the annual exempt amount (£12,000 in 2026/27) in a tax year, you may still need to report even if no tax is owed. When in doubt, report — HMRC's penalties for late CGT reporting can be significant.