You've done the hard part and worked out your gains and income. Now, where does it all go on the tax return? Many online guides still point to the wrong boxes. Crypto now has its own section on the capital gains pages. Here's exactly what to enter, box by box, with a worked example.
Quick answer (2025/26 return, due 31 January 2027)
- Crypto disposals: SA108 "Capital Gains Tax summary", cryptoasset section, boxes 13.1–13.8. Don't use the "other property, assets and gains" boxes 14–22.
- Staking and other crypto income: SA100 page TR 3, "Other UK income", boxes 17–21.
- Computations: HMRC's notes say you must send them with the capital gains pages.
Step 1: Do you need to complete the capital gains pages?
Fill in the SA108 if any of these apply:
- you disposed of chargeable assets worth more than £50,000 in total;
- your gains before losses were more than £3,000 (the annual exempt amount);
- you want to claim a capital loss or make a claim or election.
If none apply, you don't need the capital gains pages for crypto, but keep your records.
Step 2: The cryptoasset section (SA108, boxes 13.1–13.8)
| Box | What to enter |
|---|---|
| 13.1 Number of disposals | Total crypto disposals in the year (each sale, swap, spend or gift) |
| 13.2 Disposal proceeds | Total £ value received, before any reliefs, claims or elections |
| 13.3 Allowable costs (including purchase price) | Total matched costs plus allowable fees |
| 13.4 Gains in the year, before losses | Total of the gains on gain-making disposals |
| 13.5 Losses in the year | Total of the losses on loss-making disposals |
| 13.6 Claim or election code | Only if you're making a claim or election (code table in the SA108 notes) |
| 13.7 Gains/losses reported on Real Time Transaction returns | Only if you used HMRC's "real time" CGT service for crypto |
| 13.8 Tax on gains in box 13.7 already paid | As above |
Note: box 13.4 and box 13.5 are separate totals. Don't net gains and losses into one figure. Losses brought forward from earlier years go in the "Losses and adjustments" section (box 45 onwards).
Step 3: Staking and other crypto income (SA100, page TR 3)
| Box | What to enter |
|---|---|
| 17 Other taxable income | Your miscellaneous crypto income. If you claim the £1,000 trading allowance, enter the amount after deducting it. |
| 18 Total allowable expenses | Actual expenses, or leave blank if you claimed the allowance |
| 19 Any tax taken off box 17 | Usually blank |
| 21 Description | e.g. "Cryptoasset staking rewards £1,300 – trading income allowance £1,000 claimed" |
More detail: Crypto staking tax UK.
Step 4: Worked example (2025/26)
Ayesha, a higher-rate taxpayer, had in 2025/26:
- 12 crypto disposals (sales and swaps): proceeds £58,400, matched costs and fees £49,900
- gain-making disposals totalling £10,300; loss-making disposals totalling £1,800
- £1,300 of ETH staking rewards (no other trading income)
Her entries:
| Where | Box | Entry |
|---|---|---|
| SA108 cryptoassets | 13.1 | 12 |
| 13.2 | £58,400 | |
| 13.3 | £49,900 | |
| 13.4 | £10,300 | |
| 13.5 | £1,800 | |
| SA100 "Other UK income" | 17 | £300 |
| 18 | blank | |
| 21 | Cryptoasset staking rewards £1,300, trading allowance claimed |
Her tax:
- Net gains £8,500 − £3,000 exempt = £5,500 × 24% = £1,320 CGT
- Staking £300 × 40% = £120 income tax
- Total: £1,440, payable by 31 January 2027
Her proceeds were over £50,000, so she had to complete the capital gains pages even though her net gain was modest.
Step 5: Send your computations
HMRC's SA108 notes say you must send your computations (calculations) with the capital gains pages. In practice:
- Commercial filing software usually lets you attach a PDF, such as your crypto tax software's capital gains report.
- If you file through HMRC's own online service, use the "Any other information" space to summarise the calculation method and keep the full report ready to send on request.
- Your computation should show each disposal, the matching rule applied, proceeds, costs and gain or loss.
Step 6: Don't forget these
- On the main return, answer "Yes" to the question about capital gains, so the SA108 pages are included.
- Register for Self Assessment by 5 October after the tax year if it's your first return.
- Payments on account: if your total tax due through Self Assessment is over £1,000, HMRC may ask for advance payments for the next year.
- Losses: report them now, even in a year with no gains. Unreported losses expire after 4 years.
Common mistakes
- Entering crypto in the "other property, assets and gains" boxes (14–22) instead of 13.1–13.8.
- Netting gains and losses into box 13.4.
- Putting staking on the self-employment pages.
- Entering £1,300 in box 17 and £1,000 in box 18 instead of £300 in box 17.
- Missing the £50,000 proceeds rule and not filing the SA108 at all.
- Sending no computation.
Part of our series: Crypto tax UK 2026/27: the complete guide
Related: Crypto capital gains tax · Crypto staking tax · Self Assessment service
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Box numbers are from the 2025/26 SA100 and SA108 (filed by 31 January 2027). Check the current year's forms before filing. General information, not personal advice.