Legal issues
What HMRC will see
User identity, tax residence and transaction summaries from reporting platforms, combined with bank data and other sources.
Civil and criminal routes
- Nudge letters and compliance checks: requests to review your returns.
- Voluntary disclosure through HMRC's crypto disclosure service, with tax, interest and penalties.
- Code of Practice 9 for suspected serious fraud, a civil route.
- Criminal investigation, reserved for cases where HMRC considers criminal sanction appropriate, such as deliberate concealment.
Time limits for HMRC to assess tax are generally four years, six for carelessness and twenty for deliberate behaviour.
Evidence that matters
- Full transaction exports from every exchange and wallet, including closed accounts.
- Bank records showing fiat deposits and withdrawals.
- Records of staking, mining, airdrops and DeFi activity.
- Any earlier calculations or software reports used.
Reasonable lines of enquiry
Reconstruct each tax year, apply the share-pooling rules, and identify whether losses or allowable costs reduce the liability. Assess honestly whether past failures were innocent, careless or deliberate, since that drives penalties and the disclosure period.
What happens next
If you disclose voluntarily, HMRC reviews the figures and may ask questions. If HMRC opens an enquiry or investigation first, the route it chooses shapes your response. If you are invited to a criminal interview under caution, do not attend without a solicitor. See HMRC criminal investigations.
Immediate steps
- Do not ignore an HMRC letter about crypto.
- Do not delete accounts or records.
- Get legal advice before any disclosure if the conduct could be seen as deliberate, so the disclosure does not create avoidable criminal risk.
What should you send us?
Send any HMRC letter, the tax years affected and the name of your accountant if you have one.