Capital gains tax calculator
Work out what you owe on a disposal in the 2026 to 2027 tax year. Gains stack on top of your income, so the same gain can be taxed at 18% and 24% at once. This calculator splits it the way HMRC does instead of making you pick one rate.
Works for cryptoassets, shares, funds, second properties and land.
Read this before you rely on the number. It assumes England, Wales or Northern Ireland rates, one tax year, and that your gain qualifies for neither Business Asset Disposal Relief nor Private Residence Relief. It does not apply share pooling, the same day rule or the 30 day rule, which routinely change a crypto or share gain by more than the tax itself. Treat it as a sanity check on a figure you already have.
Enter your income and your gains to see the calculation.
What this calculator handles, stated plainly
Most free CGT calculators take one gain figure and one salary and stop there. Several of the biggest ones say so themselves in the small print, single transaction only, no losses, no carried forward allowance. This one takes your income, your total gains across every disposal, the losses you are offsetting and whether the £3,000 allowance is already used, then splits the result across the 18 and 24 per cent bands by filling whatever basic rate band your income leaves free. Rates were checked against HMRC’s published figures on 25 August 2026.
What every estimator misses, including this one, is what your gain actually is. That number comes from the matching rules, same day, then 30 days, then the Section 104 pool, applied to your real transaction history. For crypto we built a separate free tool that runs those rules on your actual data, the crypto tax calculator, and as far as we can find it is the only free page anywhere that does. No signup, no email gate.
Two timing rules sit outside any calculator and catch people every year. Tax due on UK residential property must be reported and paid within 60 days of completion on its own return, not the following January, and our guide to second property sales covers the mechanics. And if you sold before 30 October 2024, that older disposal carries the previous 10 and 20 per cent rates, so mixed years need the disposal dates checked one by one.
Scottish taxpayers, one quirk in your favour to know about. Capital gains tax ignores the Scottish income tax bands entirely, so the 18 to 24 split runs off the UK wide £50,270 threshold no matter what rate your salary is taxed at.
How the calculation works
Start with the gain. That is what you sold it for, minus what you paid, minus costs you were allowed to deduct along the way. Broker commission, exchange fees, stamp duty on the original purchase, legal and estate agent fees on a property. People leave these out and hand HMRC more than they owe.
Then take off losses, then the annual exempt amount, which is £3,000 for individuals and does not roll over into next year. What survives is your taxable gain.
Now the part most calculators skip. Your gain is stacked on top of your income and taxed at whatever band it lands in. Whatever is left of your basic rate band, which runs to £50,270, gets taxed at 18%. Everything above it goes at 24%. Earn £40,000 and make a £30,000 gain and you will pay both rates on the same disposal.
That is why the tool asks for your income. A calculator that makes you choose between basic and higher rate is answering a simpler question than the one HMRC asks.
Where an estimate stops being enough
The arithmetic above is the easy half. The hard half is deciding what your gain actually was, and there are three places this tool cannot help.
Matching rules. With shares or cryptoassets you do not choose which units you sold. Anything bought the same day is matched first, anything bought in the next 30 days comes second, and only then does the rest come out of your pooled average cost. HMRC sets this out for cryptoassets from CRYPTO22250 onwards. Sell at a loss and buy back within a month and the loss you were counting on gets absorbed into the new holding.
Reliefs. Private Residence Relief, Business Asset Disposal Relief at 18%, gift holdover, spouse transfers. Any one of them can change the answer to nothing owed at all, and none of them apply automatically.
Deadlines. Sell UK residential property and you have 60 days from completion to report and pay, separate from your tax return. Miss it and interest and penalties follow. Everything else goes through Self Assessment.
If your number comes from crypto software, treat it as a first draft. Missing acquisition data gets recorded as a zero cost, which taxes the whole proceeds as gain, and wallet transfers between your own addresses get logged as sales that never happened. Our reconciliation service exists because of exactly that, and the capital gains tax accountant page covers how we handle the rest.
Questions about the calculation
How much capital gains tax will I pay?
On gains above your £3,000 allowance, 18% on whatever fits in the rest of your basic rate band and 24% above that. Because the gain sits on top of your income, two people with identical gains and different salaries pay different amounts.
Does HMRC have its own calculator?
HMRC publishes tools for some situations, mainly property. They are accurate on the arithmetic and do not attempt the hard part, which is working out your acquisition cost across years of trades and transfers.
Can I use this for crypto?
For the tax arithmetic, yes. For the gain itself, only if you already trust the figure going in. Pooling and the 30 day rule decide what a crypto gain is, and getting those wrong moves the number far more than the rate does.
What if I made a loss?
Losses reduce your gains in the same year, then carry forward with no expiry. A loss only counts once you quantify it and tell HMRC, and you have four years from the end of that tax year to do it. Unreported losses are worth nothing.
Are Scottish rates different?
No, and this surprises people. Capital gains tax is not devolved, so the 18 and 24 per cent split runs off the UK wide £50,270 threshold even for Scottish taxpayers, whatever Scottish bands your salary is taxed under. Enter your income as normal and the calculator applies the right line.
I sold a house. When do I pay?
Within 60 days of completion if any tax is due, on a standalone property return, with penalties and interest running from day 61. The gain then appears again on your Self Assessment return if you file one, with the tax already paid credited against the total.
Not sure the gain is right?
Most of the money is won or lost before the rate is applied. Send us the figures and we will tell you whether they hold up.