Capital gains tax calculator
UK capital gains tax with the £3,000 exempt amount and the gain stacked on top of your income, which is what decides whether you pay 18% or 24%.
Covers 2026-27 tax year · rates as at 2026-04-06
Capital gains tax
Estimate£4,784.00
3,000 exempt, then 18% and 24%
- Gain after tax
- £20,216
- Taxed at 18%
- £8,270.00
- Taxed at 24%
- £13,730
| Gain | £25,000 |
|---|---|
| Annual exempt amount | -£3,000.00 |
| Basic-rate headroom after income | £8,270.00 |
| At 18% | -£1,489.00 |
| At 24% | -£3,295.00 |
| Gain after tax | £20,216 |
- The gain sits on top of your income, so £8,270 of basic-rate band is left before the higher rate applies.
- The annual exempt amount fell from £12,300 in 2022-23 to £3,000, so far more disposals are now reportable.
On a £25,000 gain with £42,000 of income, £3,000 is exempt and only £8,270 of basic-rate band remains — so most of the gain is taxed at 24%, not 18%.
How this is calculated
How this is calculated
The gain sits on top of your income
Your income fills the basic-rate band first. With £42,000 of income only £8,270 of the £50,270 band is left, so £8,270 of gain is taxed at 18% and the rest at 24% — even though your salary alone is a basic-rate salary.
headroom = £50,270 − income; gain above it is taxed at 24%The exempt amount has collapsed
It was £12,300 in 2022-23 and is £3,000 now. A disposal that produced no tax and no reporting three years ago can now produce both, which is why far more people receive assessments than expect to.
Losses come off before the exemption
Capital losses in the same year reduce the gain first, and only then is the £3,000 applied. Carried-forward losses are used after the exemption, which preserves more of them for future years — the ordering matters.
Worked example: £25,000 gain on shares with £42,000 of income
| Gain | £25,000 |
|---|---|
| Income | £42,000 |
| Asset | Shares |
| Exempt | £3,000 |
|---|---|
| At 18% | £8,270 |
| At 24% | £13,730 |
Realising £8,270 of gain this tax year and the rest after 6 April would use two annual exemptions and two lots of basic-rate headroom, cutting the bill substantially.
What this assumes
- A UK-resident individual, not a company or trust.
- Assets held outside an ISA or pension.
- No capital losses brought forward.
- No business asset disposal relief claimed.
Where this commonly goes wrong
- Residential property gains must be reported and paid within 60 days of completion, separately from your usual return — missing that window brings penalties.
- Selling and rebuying the same shares within 30 days is caught by the bed-and-breakfast rule, so the gain is not crystallised as intended.
- Transfers between spouses are free of CGT and reset the acquisition cost, which is the simplest way to use two annual exemptions instead of one.
Questions
How much capital gains tax will I pay?
On a £25,000 gain with £42,000 of income, £3,000 is exempt, £8,270 is taxed at 18% and the remaining £13,730 at 24%. The rate split depends on your income, not on the gain alone.
What is the capital gains annual exempt amount?
£3,000 for individuals, down from £12,300 in 2022-23. Anything above it is taxable, and gains above the reporting threshold must be declared even where no tax ends up being due.
Why am I paying 24% when I am a basic-rate taxpayer?
Because the gain stacks on top of your income. With £42,000 of income only £8,270 of the basic-rate band is left, so anything beyond that is charged at 24% even though your salary alone sits in the basic band.
How can I reduce capital gains tax?
Spread disposals across tax years to use more than one exemption, transfer assets to a spouse to double the allowance, offset losses, and hold assets inside an ISA or pension where gains are not taxable at all.
When do I have to report a property gain?
Within 60 days of completion for UK residential property, with payment due at the same time. That is separate from your annual return, and the deadline is missed often enough to be a common source of penalties.
Do I pay capital gains tax inside an ISA?
No. Gains inside an ISA or pension are entirely free of capital gains tax and need no reporting, which is why moving holdings into a wrapper before they grow is usually more valuable than managing the tax afterwards.
Related tools
Sources
General estimate based on published HMRC rates for 2026-27 tax year. Not tax advice. Confirm your position with HMRC or a qualified adviser.
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