The New Cryptoasset Boxes on SA108: A Walkthrough for 2025-26
Crypto used to share a section on SA108 with second homes, antiques and forex. From 2024-25 onwards it has its own block: boxes 13.1 through 13.8 on page CG 1. If you filed a return last year and went looking for crypto in “Other property, assets and gains”, that’s why it isn’t there any more.
Why crypto got its own section
The split is partly cleaner reporting and partly groundwork for the new Cryptoasset Reporting Framework. From 1 January 2026, UK exchanges collect customer data and forward it to HMRC; the first information exchange is due 31 May 2027. After that, HMRC will be reading crypto data straight from the source — and your SA108 needs to match the shape of what they already have.
Boxes 13.1 through 13.8
For most people, only 13.1 through 13.5 matter. The rest cover claims and Real Time Transaction reporting.
| Box | Field | What goes in |
|---|---|---|
| 13.1 | Number of disposals | Count of disposals — each sell, swap, spend or gift counts as one. |
| 13.2 | Disposal proceeds | Total GBP value received from all crypto disposals. |
| 13.3 | Allowable costs | Cost basis of the crypto disposed of, plus fees. |
| 13.4 | Gains in the year, before losses | Sum of gains — winners only. |
| 13.5 | Losses in the year | Sum of losses — losers only. |
| 13.6 | Claim or election code | Three-letter code if you’re making a claim. Usually blank. |
| 13.7 | Gains/losses already reported | Crypto gains already reported via HMRC’s Real Time Transaction service. |
| 13.8 | Tax already paid | Tax already paid on those reported gains. |
A small Binance year
Three crypto disposals during 2025-26:
| Event | Date | Gain/(Loss) | Goes to |
|---|---|---|---|
| Sold 0.5 BTC for USDT | 15 May 2025 | £3,200 | Box 13.4 |
| Swapped 5 ETH for SOL | 10 August 2025 | (£800) | Box 13.5 |
| Sold 10,000 USDT for GBP | 2 February 2026 | £40 | Box 13.4 |
The ETH-for-SOL swap is one trade in your Binance history but two events for tax: a disposal of ETH and an acquisition of SOL (CRYPTO22100). The £800 loss is matched against your Section 104 ETH pool in GBP, using the GBP value of SOL at the moment of the swap. SOL itself only becomes a tax event when you dispose of it.
The 10,000 USDT sale is also a disposal — “a stablecoin” doesn’t exempt anything. The dollar value barely moves, but the GBP–USD rate may have shifted between buying and selling. Hence £40.
The boxes:
- 13.1 — 3 disposals
- 13.2 — total GBP proceeds across all three
- 13.3 — total allowable costs from your Section 104 pools
- 13.4 — £3,240 (the two winners: £3,200 + £40)
- 13.5 — £800
- 13.6–13.8 — blank
Don’t put crypto under listed shares
Boxes 24–27 are for listed shares. 13.2–13.5 are for crypto. HMRC reconciles each block against different data sources, so crypto totals must go in 13.x. If you have both shares and crypto, fill in both sections.
How the calculator helps
Upload your Binance trade history (plus a Statements CSV if you had staking, earn or airdrop activity) and we apply the same HMRC matching rules to crypto as we do to shares: Same Day, Bed & Breakfast (30 days), then Section 104 Pool. You get a per-disposal breakdown showing the matched rule and the GBP figures behind it. For the “why” behind swaps, fees and stablecoin pricing, see our deeper write-up on how UK crypto CGT calculations work.
One caveat. The Assessment Summary still groups crypto disposals into the “Stocks” row. Until we split it out, find your crypto tickers (BTC, ETH, USDT, …) in the Stock Disposals table, sum their proceeds, costs, gains and losses on their own, and put those subtotals in 13.2–13.5. Listed-share totals stay in 24–27.
Sources
- SA108 Capital Gains Summary 2025-26 (PDF) — the form itself
- SA108 Notes 2025-26 (PDF) — HMRC’s line-by-line guidance
- Self Assessment: Capital Gains Summary (SA108) – GOV.UK
- CRYPTO22100 — Crypto-to-crypto swaps are disposals
- CRYPTO22200 — Crypto as property, CGT applies