UK Crypto Tax Calculator — Free HMRC Report
Import your exchange files and get your capital gains under HMRC’s matching rules, a Section 104 pool statement and the figures for your Self Assessment return. No upload, no sign-up, no paywall.
Your transaction files never leave your device. How to check this yourself
Figures for general information, not tax advice. Rules applied: HMRC share-pooling rules for individuals; not for companies or traders. Disclaimer
How to work out your UK crypto tax in three steps
For Capital Gains Tax, HMRC counts more than sales for pounds. Swapping one token for another, spending tokens on goods or services and giving them away (other than to a spouse or civil partner) are all disposals (CRYPTO22100). Each disposal needs a sterling value and a matched cost, and the cost has to come from HMRC’s matching rules rather than from whichever purchase you’d like to use. That is where most spreadsheets go wrong, and it’s the part this calculator does for you.
- 1
Import every account
Download the full transaction history from each exchange and wallet you used, including years before this one, so the Section 104 pool starts from the right cost.
- 2
Review what Ledger flags
Confirm transfers between your own accounts, give a cost to deposits that arrived from elsewhere, and decide on any transaction type the file didn’t explain.
- 3
Download the report
Pick the tax year and download the PDF and CSVs: SA108 figures, a per-disposal ledger with the rule for each match, and the pool statement.
What you get
- Same-day, 30-day and Section 104 matching for each token
- Every disposal shows the rule used and the HMRC manual reference
- Section 104 pool statement: opening balance, every movement, closing balance
- Capital gains summary figures for the SA108 pages
- Annual exempt amount and £50,000 proceeds checks
- 2024-25 gains split at 30 October 2024, when the rates changed
- Staking income listed separately, with its value carried into cost
- PDF report and CSV ledger, free and without a watermark
What happens to your files
Your transaction files never leave your device. CryptoTaxOwl reads them and calculates your report inside this browser tab. We don’t upload them, and the ads and analytics on this website can’t see them: the calculator runs in a separate, ad-free part of the site. To value your trades we download the same price file for every visitor, so even that doesn’t reveal what you hold.
The workspace reads your CSV and XLSX files inside your browser tab. The matching, the pool arithmetic and the PDF are all produced on your device, and closing the tab clears them unless you choose to save a project file. You can check this yourself: open your browser’s developer tools, watch the Network panel while you import, and you’ll see no request carrying your data. Our step-by-step check walks you through it.
We will never ask for your exchange password, API keys, wallet addresses or recovery phrase. If text that looks like a recovery phrase is pasted into a field, the workspace refuses it and warns you.
HMRC’s 30-day example, worked through
This is HMRC’s own example of the 30-day rule (CRYPTO22253). It’s one of the official examples we use to test the UK engine, and the figures below are HMRC’s.
Starting point: a Section 104 pool of 2,000 tokens of “C” with a pooled cost of £1,000
| Date | Event | Tokens | £ |
|---|---|---|---|
| 31 March | Sell | 1,000 | 400 |
| 20 April | Sell | 500 | 150 |
| 21 April | Buy | 700 | 175 |
| 28 April | Buy | 500 | 100 |
| 1 May | Buy | 500 | 150 |
31 March sale. No same-day purchase, so the 30-day rule looks at purchases in the next 30 days, earliest first. The 700 tokens bought on 21 April cost £175, and 300 of the 500 bought on 28 April cost £60 (300/500 × £100). Cost £235, proceeds £400, so the gain is +£165.
20 April sale. The remaining 200 tokens from 28 April (£40) and 300 of the 500 bought on 1 May (£90) are matched. Cost £130, proceeds £150, so the gain is +£20.
The pool. Only the 200 tokens left over from 1 May (£60) go into the pool, which becomes 2,200 tokens with a cost of £1,060. The pool was never touched by either sale.
Notice that the 31 March and 20 April sales sit in different tax years, either side of 5 April, but the 30-day rule still reaches across the year end. In the workspace each of these lines shows “30-day rule, TCGA 1992 s106A” with a link, so you can see exactly why a cost was used.
Do I need to report? The £3,000 allowance and the £50,000 proceeds rule
The Capital Gains Tax annual exempt amount is £3,000 for 2024-25 and 2025-26 (HMRC rates and allowances). If your total gains after losses are above it, you need to report and pay. Reporting can be needed even when no tax is due: if you’re registered for Self Assessment and the total you sold assets for was more than £50,000, gov.uk says you must report the gains (gov.uk: work out if you need to pay).
Every swap counts towards that proceeds total, so an active year of token-to-token trading can cross £50,000 while your net gain stays small. The report shows both checks side by side: gains against the allowance, and total proceeds against the threshold. It doesn’t calculate the tax itself unless you add your income band, because the rate depends on your other income (gov.uk: CGT rates).
Where the figures go on your Self Assessment return
Gains and losses on cryptoassets go on the capital gains summary pages of the return, SA108 (HMRC: SA108). The report gives you the figures those pages ask for:
- the number of disposals;
- disposal proceeds;
- allowable costs, including fees;
- gains in the year, before losses;
- losses in the year.
Each figure carries a short “where this goes” label. Box numbers can change between years, so check them against the SA108 notes for the year you’re filing. For 2025-26 the online return and any tax due are due by 31 January 2027 (gov.uk: deadlines); see the deadline calendar for the rest.
2024-25: why your gains are split at 30 October 2024
The main Capital Gains Tax rates changed part-way through the 2024-25 tax year. For disposals before 30 October 2024 the rates were 10% and 20%; from 30 October 2024 they are 18% and 24%, and the same rates apply in 2025-26 (HMRC rates and allowances). Because the return treats the two periods differently, the 2024-25 report shows gains on disposals before 30 October 2024 and on or after it as separate totals. For 2025-26 there is a single period.
Good to know
- Individuals only. The rules applied are HMRC’s share-pooling rules for individuals investing. They aren’t the rules for companies, and they don’t decide whether you’re trading.
- “Same day” means the UK calendar date. HMRC’s guidance doesn’t name a time zone, so we use the date in London and print that choice in the report.
- Missing history changes your cost. The Section 104 pool needs every purchase since you started. If you import only this year, older holdings arrive without a cost and Ledger asks you what to do with them.
- Airdrops and staking are treated differently. By default an airdrop you did nothing for is a zero-cost acquisition, and staking rewards are income whose value becomes their cost. You can change either per item; see the staking and airdrops guide.
- Report losses in time. A loss can be set against future gains only if you report it within four years of the end of the tax year (gov.uk: losses).
CryptoTaxOwl produces figures for general information. It isn’t tax, legal or financial advice, and it can only be as complete as the files you import. Check the warnings in this report, keep your own records, and speak to a qualified tax adviser if you’re unsure. You are responsible for what you file. Rules applied: HMRC share-pooling rules for individuals; not for companies or traders.
Related calculators and guides
- UK crypto tax: the same-day, 30-day and Section 104 rules explainedHMRC’s three matching rules, in order, with the official worked examples restated step by step.
- Moving crypto between your own wallets: why it isn’t a sale, and how to fix mismatchesSelf-transfers, network fees, and the unmatched deposits that quietly inflate tax reports.
- How staking rewards and airdrops are taxed in the US, UK, Canada, Australia and GermanyIncome or capital? When rewards are taxed, how they’re valued and how that value becomes your cost later.
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Questions people ask
Is swapping one crypto for another taxable in the UK?
Yes, it’s a disposal. HMRC treats exchanging one type of token for another as a disposal for Capital Gains Tax (CRYPTO22100). You need the pound value of the tokens you gave up; the calculator uses the value in your exchange file where there is one.
What counts as an allowable cost?
The price you paid, exchange fees on the purchase and sale, and some other costs listed by HMRC (CRYPTO22150). Fees in your exchange files are added automatically and shown in the ledger.
Can I use FIFO instead of Section 104?
Not for tokens of the same type held as an individual investor. HMRC’s guidance applies the same-day rule, then the 30-day rule, then the Section 104 pool (CRYPTO22200). The order isn’t a choice, which is why the UK calculator has no method setting.
Does moving crypto between my own wallets count as a sale?
No. Moving tokens between wallets you control isn’t a disposal. The workspace suggests matches between withdrawals and deposits and asks you to confirm them, so transfers don’t show up as sales. Our transfers guide explains the details.
Do I pay tax on crypto I haven’t sold?
Holding tokens that have gone up in value isn’t a disposal, so there’s no Capital Gains Tax until you sell, swap, spend or give them away. Rewards such as staking can be taxable when you receive them, which is a separate question covered in the staking guide.
Which tax years can I calculate?
The UK workspace supports 2025-26 and 2024-25. It uses every transaction you import, from any year, to build the pool, then reports the disposals in the year you pick.