CryptoTax UK · Guide
Crypto Tax Audit Preparation UK — HMRC Enquiry Guide
HMRC is increasingly active in checking crypto tax compliance. This guide explains what an HMRC enquiry looks like and how to prepare your records. Educational only — not tax advice; seek specialist representation if HMRC opens an enquiry.
Calculate my crypto gains →What triggers an HMRC crypto enquiry?
HMRC uses several methods to identify crypto taxpayers who may have under-reported: data from UK-registered exchanges (including under CARF from 2026), blockchain analytics tools, information from foreign tax authorities, and risk-profiling of Self Assessment returns.
What HMRC will ask for
In a crypto enquiry, HMRC typically requests: full transaction histories from all exchanges and wallets, evidence of cost basis calculations, bank statements showing fiat in/out flows, and an explanation of the methodology used to calculate gains.
Responding to an HMRC enquiry
If HMRC opens a formal enquiry (via a Section 9A notice), you must respond within the stated timeframe. It is strongly advisable to engage a qualified tax adviser or accountant with crypto experience before responding.
Frequently asked questions
How long can HMRC go back on crypto tax enquiries?
HMRC can normally go back 4 years for innocent errors, 6 years for careless errors, and 20 years for deliberate non-disclosure.
What if I have not filed crypto gains in previous years?
Consider using HMRC's Voluntary Disclosure facility (the Digital Disclosure Service) to come forward before HMRC contacts you.
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Calculate my crypto gains →Educational guidance only. CryptoTax UK is not a regulated tax adviser and the information above does not constitute tax, legal or financial advice. Always confirm your specific position with HMRC or a qualified accountant before filing.