SA108 Cryptoassets Boxes 13.1 to 13.8 Explained

Updated 17 October 2026

General information only, not tax advice. We are not HMRC and are not affiliated with it. Check GOV.UK. Sources read October 17, 2026. Anything marked expected should be re-checked (re-check planned December 1, 2026). Examples use GOV.UK's own figures or made-up figures. Do not enter personal identifiers (National Insurance number, UTR, name, date of birth) on this site. This page contains no affiliate links.

Short answer: On the 2025 to 2026 Capital Gains Tax summary (SA108), HMRC's notes describe a cryptoassets section with eight boxes, 13.1 to 13.8. The notes say to fill in the summary pages if, for example, you disposed of chargeable assets worth more than £50,000, or your gains before losses were more than £3,000, or you want to claim an allowable loss or make a claim or election. The tax year runs 6 April 2025 to 5 April 2026 and the online return deadline is 31 January 2027.

The boxes (HMRC notes)

Box What HMRC says to enter
13.1 Number of disposals in the year (ignore disposals not made in your own capacity, e.g. as a trustee)
13.2 Disposal proceeds, before taking off reliefs, claims or elections
13.3 Allowable costs, including purchase price
13.4 Gains in the year, before losses, after reliefs/claims that reduce total gains; not amounts charged at a different rate (e.g. BADR); must include any gains inside the 13.7 amount
13.5 Losses in the year, after reliefs/claims; must include any losses inside the 13.7 amount
13.6 The 3-letter code if you make a claim or election (you must also explain it in your computation)
13.7 Total gain or loss reported through the real time CGT service for cryptoassets (minus sign if a loss); also include these in 13.4 and 13.5; put real-time reference numbers in box 54
13.8 Tax already paid on the gains in 13.7 through the real time service

Gains and losses are entered as separate totals, not netted. Amounts are in pounds sterling (valuation in pounds).

Where your numbers come from

Your disposals count, proceeds and costs come from your own computation using same-day, 30-day and section 104 pooling rules (pooling example). Allowable costs: what counts.

Made-up example

For the year you have 12 disposals, total proceeds £18,400, allowable costs £14,900. Suppose your gains on profitable disposals total £4,100 and losses on others £600 (the netting is £3,500, but the form asks for the two totals). You would enter 12 in 13.1, £18,400 in 13.2, £14,900 in 13.3, £4,100 in 13.4 and £600 in 13.5, assuming no claims and no real-time reports.

A loss claim

If you want to claim an allowable loss you fill in the summary pages even if you are below the £3,000 gains figure (report gains and losses; lost or stolen crypto).

FAQ

Is there a box for crypto income like staking? Not in these boxes; see [crypto income](../crypto-income-uk-staking-airdrops-mining-tax/).

Does the form call these "boxes 14 to 17" too? Boxes 14 to 22 are for other property and assets; crypto has its own 13.x boxes.

What we could not verify

Uncertain. These points were not confirmed on the pages read. A re-check of the GOV.UK pages is planned for 1 December 2026.

  • The 3-letter claim codes table (page CGN 4 of the notes): not read.
  • The real time CGT service rules and deadlines: not read.
  • Whether the 2026 to 2027 form will keep the same box numbers (expected, not published).
  • How HMRC treats part-year or trustee cases beyond the sentence quoted.
  • The £50,000 and £3,000 tests apply to all chargeable assets together, not to crypto alone (as the notes are written); individual cases may need advice.

Sources (official)

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