Reporting Crypto Gains and Losses in the UK: Self Assessment and Claims

Updated 17 October 2026

General information only, not tax advice. We are not HMRC and are not affiliated with it. Check GOV.UK and your platform. Last checked against GOV.UK: 17 October 2026. Anything marked expected should be re-checked. Examples use 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: GOV.UK says that if your total gain for the tax year (6 April to 5 April) is above the CGT tax-free allowance, you must report it and pay CGT, either on a Self Assessment return or through the Capital Gains Tax real time service. Self Assessment returns have a cryptoasset section from tax year 2024 to 2025 onwards, and you complete it in pound sterling.

Dates

The 2026-27 tax year ends 5 April 2027. A 2026-27 Self Assessment return is expected to be due 31 January 2028 under the usual rule (our extension of GOV.UK's 2025-26 date; not confirmed for 2026-27) (key dates cover the CARF dates).

Reporting losses

• GOV.UK says capital losses on other assets can reduce your gain, but you must report them first.
• A loss is deducted from the gains of the same tax year; unused losses from earlier years can then be deducted if your total taxable gain is still above the allowance, and the remainder carried forward.
• You don't have to report a loss straight away: you can claim up to 4 years after the end of the tax year of the disposal.
• If you've never made a gain and aren't registered for Self Assessment, you can write to HMRC instead.

Tokens that have become worthless: negligible value claims

HMRC's manual says you can crystallise a loss on tokens you still own if they become worthless or of "negligible value". The claim treats the tokens as disposed of and immediately re-acquired at an amount you state (which may be £nil). Because tokens are pooled, the claim must cover the whole section 104 pool of that token, not individual tokens. It must state the asset, the amount (possibly nil) and the date; it can be made when you report the loss. HMRC's manual adds that the deemed disposal date is generally the date HMRC receives the claim, that there is no fixed time limit for making the claim, and that a resulting loss must also be notified to HMRC (it can be in the same return).

Records and earlier years

Keep the records listed in reconciling your records. GOV.UK says you can use HMRC's Cryptoasset Disclosure Service if you need to disclose unpaid tax for earlier years.

FAQ

Do exchange reports go on my return? GOV.UK says they can be essential for working out tax, but they aren't tax calculations.

Is stolen crypto a loss? HMRC's manual says theft isn't a disposal, so there is no loss as such; but where there is no likelihood the asset will be recovered, a negligible value claim under section 24(2) TCGA 1992 would be competent, unless the loss is covered by insurance. See lost keys or stolen crypto.

What we could not verify

The CARF Readiness Checker runs in your browser. It does not store what you enter and it does not ask for personal identifiers.