UK Capital Gains Tax Calculator

How UK Capital Gains Tax works in 2026/27

Capital Gains Tax (CGT) is the tax HMRC charges on the profit when you sell or otherwise dispose of an asset that has risen in value. It is the gain that is taxed, not the sale price. Sell a fund you bought for £20,000 for £35,000 and the chargeable gain is £15,000, not £35,000.

Every UK resident gets an annual exempt amount (AEA) of £3,000 in 2026/27. Gains below that figure are tax-free and do not normally need to be reported. Above the AEA, your remaining gain stacks on top of your other taxable income to determine the rate. Whatever portion of the gain sits within the basic-rate band (up to £50,270 of total income plus gains) is taxed at 18%. Anything above that is taxed at 24%.

Since the 30 October 2024 Budget the rates have been harmonised at 18% and 24% for both residential property AND non-property assets (shares, funds, crypto). The previous 10% / 20% rates for non-property assets are gone. This is the figure most retail investors miss: the rate on a stock-market gain rose materially with very little public attention.

The CGT allowance has been cut by 80% in three years

The £3,000 allowance is not a number that has held steady. It has been hacked down from £12,300 in 2022/23, to £6,000 in 2023/24, to £3,000 from 2024/25 onwards. That is roughly an 80% cut in three years, with no equivalent rise in the dividend allowance or any other shelter to compensate.

This is a textbook stealth tax. The headline rates of 18% and 24% sound moderate, but the threshold at which they bite has been quietly pushed down to a level where ordinary workers with a General Investment Account, a bit of crypto, or a single second property get pulled into the net. The government announced the changes without much fanfare and most retail investors only find out when their broker sends them a year-end statement and they realise they now owe CGT on a portfolio they used to be able to rebalance for free.

The practical takeaway is straightforward. If you hold investments outside an ISA or pension, you almost certainly need to act on the allowance every April rather than once a decade.

What counts as a disposal

A CGT-triggering disposal is broader than just selling. You crystallise a gain when you:

• Sell an asset for cash.
• Gift it to anyone other than your spouse, civil partner, or a registered UK charity.
• Swap it for another asset. Crypto-to-crypto trades count - swapping ETH for SOL is a disposal of the ETH.
• Transfer it out of a wrapper in a way HMRC treats as a sale (such as stripping shares out of certain structured products).
• Receive compensation for it, including some insurance payouts where an asset is lost or destroyed.

Transfers between spouses or civil partners are not disposals. The receiving partner inherits the original cost base. This is the single most powerful planning tool for couples and feeds directly into the Bed-and-Spouse technique below.

Assets that are exempt from CGT

A surprisingly large chunk of the typical UK portfolio is exempt by design. For most retail investors who plan a year ahead, CGT need not enter the picture at all.

• Stocks and Shares ISAs and JISAs. Every gain inside the wrapper is tax-free, full stop. See our Stocks and Shares ISA comparison for where to open one.
• Pensions (SIPPs, workplace pensions). Tax-free growth inside the wrapper. The ISA vs SIPP calculator helps you decide which to feed first.
• Your main home (Private Residence Relief). Sell the house you actually live in and there is normally zero CGT.
• Gifts to your spouse or civil partner, and gifts to UK-registered charities.
• UK government bonds (gilts) and most qualifying corporate bonds.
• Premium Bonds and other NS&I products.
• Personal possessions worth £6,000 or less when sold (the chattels exemption), and genuine personal-use cars.

Crypto is not exempt and cannot be held inside an ISA. Every disposal is chargeable, so active crypto traders generally rack up more CGT-reportable disposals in a year than most share investors do in a lifetime.

Bed-and-ISA, Bed-and-SIPP, and Bed-and-Spouse

Three planning techniques quietly do most of the heavy lifting for serious UK investors. Each one is legitimate, well-established, and recognised by HMRC.

Bed-and-ISA means selling a holding in your General Investment Account (GIA) and immediately rebuying the same holding inside your Stocks and Shares ISA. The sale crystallises a gain which is sheltered by the £3,000 annual exempt amount, and the repurchase resets the cost base higher AND moves the asset into a wrapper where every future gain is tax-free. Done every April for a working life, it can shift six figures of a GIA into an ISA without ever paying a penny of CGT.

Bed-and-SIPP is the same trick but using your pension instead of your ISA. It is more powerful for higher-rate taxpayers because the contribution attracts pension tax relief on top of the CGT shelter, but the money is locked up until age 55 (rising to 57 in 2028).

Bed-and-Spouse uses the inter-spouse exemption. Transfer the asset to your partner at no CGT cost, then they sell it using their own £3,000 AEA and their own basic-rate band. A married couple effectively gets £6,000 of AEA per year and two basic-rate bands to soak up gains at 18% rather than 24%.

Note the 30-day rule. If you sell a holding and buy back the same asset in the same account within 30 days, the buyback is matched against the sale rather than feeding into the cost pool. This blocks the old "bed-and-breakfast" trick of selling on 5 April and rebuying on 6 April just to crystallise an AEA-sized gain. The 30-day rule applies only to the same asset in the same account. Bed-and-ISA, Bed-and-SIPP, and Bed-and-Spouse all sit outside it because the repurchase happens in a different account or in a different person's name.

Worked example: selling a fund in your GIA

You earn £40,000 of salary and you sell £30,000 of a global equity fund from your General Investment Account. Your original investment was £20,000, so the raw gain is £10,000.

• Raw gain: £30,000 - £20,000 = £10,000
• Less annual exempt amount: £10,000 - £3,000 = £7,000 taxable gain
• Taxable income after personal allowance: £40,000 - £12,570 = £27,430
• Headroom in basic-rate band: £37,700 - £27,430 = £10,270
• All £7,000 of the gain fits inside the basic-rate band, so it is taxed at 18%.
• CGT due: £7,000 x 18% = £1,260

Had the gain instead been £25,000, the first £10,270 of headroom would have been taxed at 18% (£1,848.60) and the remaining £11,730 would have spilled into higher-rate territory at 24% (£2,815.20), for a total bill of £4,663.80. The same gain, the same investor, but a meaningfully higher bill the moment the gain breaches the basic-rate band.

For UK residential property the same gain would be reportable and payable within 60 days of completion through HMRC's online real-time CGT service. That is a much shorter window than the Self Assessment deadline most people are used to, and penalties for missing it stack up quickly. Full rate information is published on gov.uk/capital-gains-tax.

These worked examples are general guidance. If you have a complex disposal (a business sale, a part-disposal of land, an inherited holding, or significant offshore assets) a qualified UK tax adviser will save you far more than they cost.

Frequently asked questions