Capital gains tax calculator.
Estimate the Capital Gains Tax due on a gain, after your tax-free annual exempt amount. This is an estimate for general guidance only, not personalised tax advice — talk to Buzz for advice specific to your situation.
Enter the gain details
Enter your gain, then click Calculate to see an estimate.
Rates used in this calculator (2026/27 tax year)
| Capital Gains Tax | Rate |
|---|---|
| Annual exempt amount | £3,000 tax-free |
| Within your basic-rate band | 18% |
| Above your basic-rate band (higher/additional rate) | 24% |
These rates apply to most gains, including residential property, for individuals. Business Asset Disposal Relief can reduce the rate to 18% on qualifying business gains up to a £1 million lifetime limit — not included in this calculator; ask Buzz if this might apply to you. Source: gov.uk Capital Gains Tax rates and allowances page, checked July 2026.
Working out the gain before you tax it
Step one — the gain, not the proceeds. Take what you sold it for, deduct what you paid for it, then deduct the costs of buying and selling (legal fees, stamp duty on the original purchase, estate agent and auction fees) and the cost of any capital improvements. What you spent on repairs and maintenance does not count.
Step two — the annual exempt amount. The first £3,000 of gains in the tax year is tax-free. It applies once per person per year, not per disposal, and it cannot be carried forward.
Step three — the rate depends on your income, not the gain. The taxable gain is stacked on top of your income. Whatever falls inside your remaining basic-rate band is taxed at 18%; anything above it at 24%. This is why a modest gain for a low earner and the same gain for a higher-rate taxpayer produce very different bills — and why entering your other income gives a more accurate answer than picking a band.
Losses matter too. Capital losses in the same year are set against gains before the exempt amount, and unused losses can be carried forward indefinitely if you report them.
A £40,000 gain on a £45,000 income
- Gain after costs£40,000
- Less annual exempt amount−£3,000
- Taxable gain£37,000
- Basic-rate band left (£50,270 − £45,000), taxed at 18%£949
- Remaining £31,730, taxed at 24%£7,615
- Capital Gains Tax due£8,564
Note what the income does. With £45,000 of other income only £5,270 of the basic-rate band survives, so nearly the whole gain is taxed at 24%. Drop the income to £30,000 and £20,270 of the gain would fall in the 18% band instead — £900 less tax on exactly the same disposal.
That is the practical lesson: on a large gain, the timing of the disposal and the level of your income in that tax year are both levers, and they are only levers before you sell.
Reporting deadlines catch people out more than the tax does
- UK residential property has a 60-day rule. If a disposal produces a taxable gain, it must be reported and the tax paid within 60 days of completion, through HMRC's property account — separately from your tax return. Miss it and penalties start regardless of whether the tax is eventually paid.
- Everything else goes on the tax return. Shares, business assets, second properties abroad and other chargeable assets are reported through Self Assessment by 31 January after the tax year.
- Use both allowances if you are married or in a civil partnership. Transfers between spouses are on a no-gain-no-loss basis, so an asset can be put into joint names before sale to use two exempt amounts and potentially two basic-rate bands. The transfer has to be genuine and it has to happen before the sale is agreed.
- Report losses even in a year you owe nothing. Unreported losses generally cannot be used later, and they are worth up to 24% of their value against a future gain.
- Check whether a relief applies. Private residence relief on a home you have lived in, Business Asset Disposal Relief on qualifying business disposals, rollover relief on replacing business assets. None of them are in this calculator.
Common questions about Capital Gains Tax
Do I pay Capital Gains Tax on my own home?
Usually not. Private residence relief normally covers a property that has been your only or main home throughout ownership, including the final nine months even if you have moved out. It gets restricted where you let the property out, used part of it exclusively for business, owned it during a period you lived elsewhere, or the grounds exceed half a hectare. Where relief is partial, the gain is apportioned by the months of qualifying occupation against total ownership. If any of those apply to you, work the figures out before completion rather than after — the reporting deadline is short.
When do I have to report and pay?
For UK residential property, within 60 days of completion through HMRC's UK Property Account, with the tax payable on the same deadline. That is separate from your Self Assessment return, and the gain goes on both. For other assets — shares, business disposals, crypto — it goes through Self Assessment and is payable by 31 January after the end of the tax year. The 60-day rule catches people constantly, because the money has usually already been spent or reinvested by the time anyone mentions it. Penalties run from the deadline whether or not the gain is later reported correctly on the annual return.
Can I use my spouse's allowance?
Yes. Transfers between spouses and civil partners are made on a no-gain-no-loss basis, so moving an asset into joint names before a sale can use two annual exempt amounts of £3,000 each and two sets of basic-rate band, which at the 18% and 24% rates is worth real money. Two conditions matter. It has to be a genuine, outright transfer of beneficial ownership, not a paper exercise you reverse afterwards. And it must be completed before the sale is agreed — doing it after contracts are exchanged does not work, because the disposal has already happened.
What is Business Asset Disposal Relief?
A relief that reduces the rate on qualifying business disposals to 18%, subject to a £1 million lifetime limit across all claims. Qualifying conditions cover what you are selling, how long you have held it and your role — broadly, at least a 5% shareholding and voting rights in a trading company where you are an officer or employee, for a minimum period before disposal. That qualifying period is why this needs checking well before a sale rather than after: a company that has accumulated large cash reserves may no longer count as trading, and restructuring on the eve of a deal rarely works.
How is the rate actually decided?
By how much of your basic-rate Income Tax band is left once your other taxable income is counted. The gain sits on top of income: the part falling within the remaining basic-rate band is taxed at 18%, and everything above it at 24%. So the same £40,000 gain costs very different amounts for someone earning £25,000 and someone earning £70,000. This is also why timing matters — realising a gain in a year when income is low, or splitting a disposal across two tax years where the asset allows, can move part of it into the lower rate.
Are shares and crypto treated the same way?
Both are chargeable assets and both use the same rates, but the matching rules for identical holdings bought at different times are detailed: disposals match first against acquisitions on the same day, then within the following 30 days, then against the pooled average cost of everything else. Crypto adds its own problem, which is record-keeping — swapping one token for another is a disposal even though no sterling changed hands, and exchanges routinely fail to provide usable histories. Keep a full transaction record from the start. Reconstructing several years of it later is the genuinely expensive part.
What if I made a loss?
Report it. Capital losses are set against gains in the same tax year first, then carried forward indefinitely against future gains — but a carried-forward loss generally has to be claimed within four years of the end of the tax year it arose in, so an unreported loss can simply expire. That includes losses that feel like nothing at the time, such as shares in a company that has been dissolved. People diligently report gains and never mention losses, then pay tax years later on a gain that could have been reduced.
