Key takeaways
- Crypto gains go in the cryptoasset section of the SA108 capital gains pages, boxes 13.1 to 13.8 for 2025/26, and the return is due by 31 January 2027.
- Work out a gain for every disposal in pounds sterling, then match disposals under the same day rule, the 30 day rule and finally the section 104 pool.
- The annual exempt amount is £3,000, and gains above it are taxed at 18% within the basic rate band and 24% above it.
- You must fill in the capital gains pages if you disposed of chargeable assets worth more than £50,000, even with no tax to pay.
- If you are not in Self Assessment, the real time Capital Gains Tax service is an alternative: report a 2025/26 gain by 31 December 2026.
You report crypto on the Self Assessment capital gains pages, in the cryptoasset section HMRC added to the return for 2024/25 onwards. For the 2025/26 tax year that section is boxes 13.1 to 13.8 of the SA108 'Capital Gains Tax summary' pages, and it is due with the rest of your online return by 11:59pm on 31 January 2027. Everything goes in pounds sterling, worked out disposal by disposal, with your computations attached.
What counts as a disposal
Capital Gains Tax bites when you dispose of tokens, not when the price moves. The Cryptoassets Manual at CRYPTO22100 lists a disposal as:
- selling tokens for money
- exchanging tokens for a different type of token
- using tokens to pay for goods or services
- giving away tokens to another person, unless it is a gift to your spouse or civil partner
The GOV.UK guidance on selling cryptoassets also treats a gift to charity as outside the charge. Moving coins between wallets you own is not a disposal. Swapping one token for another is the one people miss: it is a disposal of the token you gave up, even though no cash moved.
Work out each disposal in pounds sterling
HMRC's rule is that you work out the gain for each transaction you make. The gain is what you disposed of the tokens for, less their allowable cost. On a crypto to crypto swap the proceeds are the pound sterling market value of what you received on the day. Where tokens move between connected persons you use market value instead of the price paid.
The allowable costs are set out in CRYPTO22150:
| Allowable | Not allowable |
|---|---|
| The consideration in pound sterling originally paid for the tokens | Costs already deducted against profits for Income Tax |
| Transaction fees paid for having the transaction included on the distributed ledger | Mining costs such as equipment and electricity |
| Advertising for a purchaser or a vendor | Fees to deposit sterling or foreign currency with an exchange |
| Professional costs of drawing up a contract for the acquisition or disposal | |
| The cost of a valuation or apportionment needed to calculate the gain or loss |
If you already paid Income Tax on the value of tokens when you received them, you do not pay Capital Gains Tax on that amount again. Your cost is the value you were taxed on, and only the growth after that is a gain.
The matching rules: same day, 30 days, then the pool
You cannot pick which coins you sold. CRYPTO22200 sets out three steps, applied in order, for each type of token. Each token type gets its own section 104 pool with its own pooled allowable cost, so bitcoin, ether and litecoin are three pools. Non-fungible tokens are separately identifiable, so they are not pooled and no matching rules apply.
| Order | Rule | What it does |
|---|---|---|
| 1 | Same day rule, TCGA 1992 s105 | Tokens of one type bought and sold on the same calendar day are treated as a single acquisition matched against a single disposal, so they never reach the pool |
| 2 | 30 day rule, TCGA 1992 s106A | Tokens bought within the 30 days after a disposal are matched to that earlier disposal, earliest disposal first, rather than going into the pool |
| 3 | Section 104 pool | Anything left is a disposal from the pool, using a proportion of the pooled allowable cost |
HMRC's own pooling example: you buy 100 token XY for £2 each, then 300 token XY for £1 each. You hold 400 tokens that cost £500, an average of £1.25 each. Sell 200 of them and the cost you deduct is £250. The pool moves with every acquisition and disposal, which is why a spreadsheet built from exchange exports rarely survives a full year of trading.
Where crypto gains go on the 2025/26 return
The SA108 pages for 2025/26 are split into nine sections, and cryptoassets have their own, boxes 13.1 to 13.8. Do not use the 'Other property, assets and gains' section for tokens.
| Box | What goes in it |
|---|---|
| 13.1 | Number of disposals made in your own capacity |
| 13.2 | Total disposal proceeds, before any reliefs, claims or elections |
| 13.3 | Total allowable costs, including purchase price |
| 13.4 | Gains in the year, before losses |
| 13.5 | Losses in the year |
| 13.6 | The 3 letter code for any claim or election |
| 13.7 | Gains or losses already reported through the real time service |
| 13.8 | Tax already paid on the box 13.7 gains |
Two things trip people up. The SA108 says you must enclose your computations, including details of each gain or loss, as well as filling in the boxes, so a Koinly report is an attachment rather than a substitute for the numbers. And anything in box 13.7 must also sit inside the box 13.4 and 13.5 totals, with the real time reference numbers in box 54. Source: the SA108 notes for 2025/26.
Where crypto income goes
Tokens you receive rather than buy are usually income. HMRC's position on the receiving cryptoassets guidance is that tokens from mining, staking or lending, including from DeFi, count as other taxable income where you are not carrying on a trade. That goes in box 17 on page TR 3 of the SA100, 'Other taxable income before expenses and tax taken off', with a description in box 21. There is a £1,000 trading and miscellaneous income allowance: if your total miscellaneous income from all sources is between £1,000 and £2,500 you contact HMRC, and above £2,500 you register for Self Assessment.
Whether a particular staking or lending return is income or a capital receipt depends on the facts of the arrangement, and HMRC says so rather than giving one rule. Our guides on staking and UK tax and DeFi tax work through what it turns on. If an employer pays you in tokens, exchange tokens like bitcoin are readily convertible assets and the tax should already have gone through PAYE.
Rates and the £3,000 annual exempt amount
The annual exempt amount is £3,000. Above it, gains are taxed at 18% to the extent they fall within your remaining basic rate Income Tax band and 24% above it, so a higher rate or additional rate taxpayer pays 24% on the lot. Crypto is taxed at these main rates, not the residential property rates. Source: GOV.UK Capital Gains Tax rates.
If your 2025/26 gains come to £15,000, the first £3,000 is covered and £12,000 is taxable, split between 18% and 24% depending on how much basic rate band is left after your other income. Our Capital Gains Tax calculator gives you the shape of the bill, and our Capital Gains Tax guide covers the rest.
When you must report even with no tax to pay
Do not use the old rule of four times the annual exempt amount: that applied to tax years before 2023/24. The SA108 notes for 2025/26 say to fill in the capital gains pages if any of these apply:
- you sold or disposed of chargeable assets which were worth more than £50,000
- your chargeable gains before taking off any losses were more than £3,000
- you have gains in an earlier year taxable in this period
- you want to claim an allowable capital loss, or make a capital gains claim or election for the year
The £50,000 test is on what you disposed of, not what you made, so a year of heavy trading that nets out to nothing can still cross it. GOV.UK confirms the figure applies for 2023/24 onwards on its work out if you need to pay page. Claiming a loss is its own trigger, which is the point of our guide to crypto losses.
The real time Capital Gains Tax service
If you are not otherwise in Self Assessment, you can report a crypto gain through HMRC's real time Capital Gains Tax service instead of filing a return. You must be a UK resident, you cannot use it on behalf of someone else, and you must attach a copy of your calculations. For a 2025/26 gain you report by 31 December 2026 and pay by 31 January 2027.
The catch: if you are already registered for Self Assessment you still have to include the disposal in your return, in boxes 13.7 and 13.8. Source: GOV.UK report and pay your Capital Gains Tax.
Records HMRC expects you to keep
HMRC will ask to see records if it opens a compliance check. For each pool you must keep separate records for each transaction showing:
- the type of tokens
- the date you disposed of them
- the number of tokens disposed of, and the number you have left
- the value of the tokens in pound sterling
- bank statements
- the pooled costs before and after the disposal
Wallet addresses are worth keeping too. HMRC is blunt about exchange reports: they are not tax calculations, and they will not keep track of your pooled costs. You must keep your own records.
Key dates for the 2025/26 return
| Date | What is due |
|---|---|
| 5 October 2026 | Register for Self Assessment if you have not filed a return before |
| 31 October 2026 | Paper return for 2025/26 |
| 31 December 2026 | Deadline to report a 2025/26 gain through the real time Capital Gains Tax service |
| 31 January 2027 | Online return for 2025/26, plus payment of the tax owed |
More on the calendar in our guide to the next Self Assessment deadline, and on the rules in crypto tax in the UK and when you pay tax on cryptocurrency.
Get your crypto return filed
GoForma's ACCA and AAT qualified accountants file crypto Self Assessment returns for £298 plus VAT. That includes a Koinly licence for up to 25,000 transactions, gains worked out across every exchange and wallet you have used, and the full return filed. A Self Assessment return without crypto is £198. We are rated 4.9 on Google from 72 reviews and have filed more than 7,000 tax returns. See our crypto tax accountants page, our crypto Self Assessment service, or book a free consultation.
