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You received an HMRC letter about crypto

An HMRC letter about crypto is frightening but not always a fine. Many are prompts to review your records. Do not ignore it — follow this path.

Quick answer

Read the letter carefully → gather exchange and wallet records → compare with what you filed → amend your return or use voluntary disclosure if tax is owed → respond within any deadline stated.

  1. Step 1 Penalties & nudge letters

    What nudge letters are

    What happens if you file late, underpay crypto tax, ignore a nudge letter, or fail CARF identity checks.

  2. Step 2 Record keeping

    Rebuild your transaction list

    What transaction records UK crypto holders must keep for HMRC — dates, sterling values, fees and a free downloadable CSV template.

  3. Step 3 When to report

    Check what you should have reported

    UK reporting rules for 2025/26 — £3,000 CGT allowance, £50,000 proceeds threshold, income triggers and CARF.

  4. Step 4 Voluntary disclosure

    If tax is owed

    How to disclose undeclared UK crypto tax — lookback years, penalties, interest and the HMRC disclosure service.

  5. Step 5 SA108 crypto boxes

    Amending SA108 figures

    Which SA108 boxes to use for UK crypto gains and losses in 2025/26 — proceeds, costs, gains, losses and income.