Capital gains tax calculator for shares
Work out the Capital Gains Tax on shares or funds you sell outside an ISA in 2026 to 2027, after the £3,000 allowance and earlier losses, at 18% and 24%.
- Capital Gains Tax to pay
- £1,843.80
- 15.4% of your £12,000 gain
- Gain
- £12,000
- £30,000 sale minus £18,000 costs
- Basic rate band left
- £5,270
- £37,700 minus £32,430 taxable income
- Losses to carry forward
- £0
- unused earlier losses, plus any loss on this sale
| Part of the gain | Amount | Tax |
|---|---|---|
| Tax-free allowance | £3,000 | £0 |
| Taxed at 18% | £5,270 | £948.60 |
| Taxed at 24% | £3,730 | £895.20 |
| Total | £12,000 | £1,843.80 |
Rules for the 2026 to 2027 tax year, checked on 28 September 2026, for shares and funds held outside an ISA or pension. The first £3,000 of gains is tax-free. The rest is taxed at 18% while it fits in the basic rate band left after your taxable income (your income minus the £12,570 Personal Allowance, which shrinks by £1 for every £2 over £100,000), and at 24% above that. Scottish taxpayers use the same bands for gains. Losses from earlier years only bring the gain down to £3,000; the rest carries forward. It treats this as your only sale in the tax year and takes the cost as you enter it: for shares bought at different times, HMRC's pooling rules set the cost. It leaves out reliefs, pension and Gift Aid payments that stretch your basic rate band, and other gains or losses this year. If you're registered for Self Assessment and sold more than £50,000 of assets in the year, you need to report them even with no tax to pay.
What goes in
Enter what you sold the shares or fund units for and what they cost, adding the costs of buying and selling them, such as dealing fees and the Stamp Duty Reserve Tax you paid when you bought. Then add your income for the tax year before tax, and any losses from earlier years you haven’t used yet.
If you bought the same shares at different times, the cost isn’t just what you paid for the ones you sold. HMRC pools them and uses the average cost, known as a section 104 holding, with separate rules for shares bought on the day you sell or in the 30 days after. HMRC’s helpsheet HS284 shows how to work it out.
What the result means
The first £3,000 of gains in the tax year is tax-free. The rest is taxed at 18% while it fits in the basic rate band left after your taxable income, which is your income minus the £12,570 Personal Allowance, and at 24% above that. The basic rate band is £37,700, and Scottish taxpayers use the same band for gains. These rates have applied since 30 October 2024.
In the example, shares sold for £30,000 that cost £18,000 make a £12,000 gain. After the £3,000 allowance, £9,000 is taxable. £45,000 of income leaves £5,270 of the basic rate band, so £5,270 is taxed at 18% (£948.60) and £3,730 at 24% (£895.20). That’s £1,843.80, 15.4% of the gain.
Losses from earlier years only bring your gains down to £3,000, so the allowance isn’t wasted, and the rest carries forward. Gains on investments inside an ISA are tax-free.
Sources
- GOV.UK: Capital Gains Tax rates and allowances
- GOV.UK: Capital Gains Tax: if you make a loss
- GOV.UK: Capital Gains Tax rates and allowances for past years
- GOV.UK: Tax when you sell shares: work out your gain and shares in the same company
- HMRC: Shares and Capital Gains Tax (HS284)
- legislation.gov.uk: Taxation of Chargeable Gains Act 1992, section 1J, which applies UK bands to Scottish taxpayers
- HMRC: Calculate Capital Gains Tax on shares