An HMRC crypto enquiry rarely arrives out of nowhere. By the time the letter lands on your doormat, HMRC usually holds exchange data, bank records, or both, and has already compared them against what you reported. Respond well, and you often settle with a modest penalty. Respond badly, or ignore the letter entirely, and you hand HMRC the evidence it needs to argue your behaviour was deliberate.
Received a letter from HMRC about your crypto? Book a confidential call with a crypto accountant who handles HMRC crypto enquiries every week. Call 0208 638 5800 or book online at Crypto Accountants.
Why Are HMRC Crypto Enquiries Rising Sharply?
HMRC Already Holds Your Exchange Records
HMRC spent years without visibility over crypto. That has ended.
Since 2019, it has used statutory information notices to compel UK-facing exchanges to hand over customer records, including names, addresses, transaction histories and wallet addresses.
Those datasets feed HMRC’s Connect system, which cross-references them against tax returns, bank accounts, Companies House filings and property records.
The Cryptoasset Reporting Framework widens the net further.
UK service providers began collecting standardised customer and transaction data on 1 January 2026, with the first reports due to HMRC in 2027 and automatic exchange with partner jurisdictions following.
Offshore exchanges no longer sit outside HMRC’s reach in the way they once did.
Your Tax Return Now Points at Crypto Directly
From the 2024-25 tax year, the Self-Assessment capital gains pages carry a separate box for cryptoasset disposals. That change gives HMRC a clean filter. It can now identify every taxpayer who appears in exchange data but left that box empty, and it runs that comparison at scale.
Nudge Letters Come Before Formal Enquiries
HMRC has issued “one to many” nudge letters to suspected crypto holders since late 2021, and the batches have grown each year.
A nudge letter is not a formal HMRC crypto enquiry. It is a prompt, and it carries a significant advantage: disclose before HMRC opens a formal investigation, and your disclosure counts as prompted but cooperative, which reduces the penalty range considerably.
What Triggers an HMRC Crypto Investigation?
Four patterns account for most enquiries, and only one of them involves anything HMRC would call dishonest. This is what puts a file on a compliance officer’s desk.
A Mismatch Between Exchange Data and Your Return
This is the most common trigger of an HMRC crypto enquiry by far.
The exchange reports disposals worth £180,000; your return shows £4,000 of gains. HMRC does not know whether you made a profit or a loss on those disposals, and it does not need to.
The mismatch alone justifies an enquiry.
Unexplained Credits Hitting Your Bank Account
Fiat withdrawals from an exchange into a personal current account create a visible trail. Where those credits sit alongside modest declared income, HMRC asks where the money came from.
Mortgage applications and large property deposits funded by crypto proceeds raise the same question.
Disposals People Never Realised Were Taxable
Plenty of enquiries start with an honest mistake. HMRC treats crypto as property, not currency, so a disposal happens whenever you swap one token for another, spend crypto on goods, or gift it to anyone other than your spouse or civil partner. Investors who only calculate gains on cash-outs often understate their position by a wide margin. Staking rewards, airdrops, mining income and DeFi yield add further layers, and the correct treatment depends on the facts rather than the label.
Failing to Register at All
If you owed tax and never filed a return, you also failed to notify HMRC of chargeability.
That is a separate offence with its own penalty regime, and it extends the period HMRC can go back and assess.
The clients who end up in the worst position are rarely the ones who set out to evade tax. They are the ones who answered HMRC’s first letter themselves, guessed at a figure, and then had to correct it later. Once HMRC holds a number you cannot stand behind, you spend the rest of the enquiry defending it.
Malik Ali FCCA, Managing Partner at Crypto Accountants, advises saying nothing about figures until your transaction history is rebuilt. Disclose in full and in one go.
Timing matters just as much, because penalties turn on whether you volunteered the information or waited to be asked. That makes the cheapest day to disclose the day you realise there is a problem.
HMRC Crypto Investigation: What Happens at Each Stage?
Stage One: The Opening Letter
Everything begins with a single sheet of paper. When HMRC challenges a return you already filed, it acts under section 9A of the Taxes Management Act 1970, and it normally has to move within twelve months of the date you filed.
Where that window has shut, or where you never filed at all, HMRC switches to a discovery assessment, which reaches considerably further back.
Read the letter for three things: the tax years it names, the taxes it covers, and the date by which you must reply. HMRC usually allows 30 to 40 days.
Alongside it you will often find a Schedule 36 information notice. That document spells out precisely what HMRC wants from you, typically exchange statements, wallet addresses, bank records and old correspondence. Your adviser can push back on both the breadth of the list and the deadline attached to it, and HMRC frequently agrees to narrow one or extend the other.
Silence is the expensive option. Ignore a Schedule 36 notice, and HMRC charges £300 immediately, then up to £60 for every further day you stay quiet.
Stage Two: Escalation to Code of Practice 8 or 9
Straightforward enquiries stay with a local compliance officer.
More serious cases move to HMRC’s Fraud Investigation Service under one of two codes.
Code of Practice 8 covers complex or high-value cases where HMRC does not yet suspect fraud. Code of Practice 9 signals that HMRC suspects deliberate behaviour and offers you the Contractual Disclosure Facility.
COP9 deserves real attention.
HMRC gives you 60 days to accept the facility and submit an outline disclosure. Accept it and make a complete, accurate disclosure, and HMRC contractually agrees not to prosecute you for the conduct you disclose. Reject it, or disclose partially, and criminal investigation stays on the table.
Nobody should answer a COP9 letter without professional representation.
Stage Three: Quantifying the Tax
You or your adviser then rebuild the full transaction history. That means every exchange, every wallet, every chain, matched under HMRC’s share pooling rules, including the same-day and 30-day matching rules.
Capital gains rates rose to 18% and 24% for disposals made on or after 30 October 2024, and the annual exempt amount now sits at £3,000, so older gains and newer gains carry different arithmetic.
Losses matter here. Many investors who owe tax on 2021 gains also hold substantial realised losses from later years, and claiming them properly can reshape the final bill.
Stage Four: Penalties and How Far Back HMRC Goes
Penalties follow behaviour, not the amount.
Careless errors attract penalties between 0% and 30% of the tax, deliberate errors between 20% and 70%, and deliberate errors with concealment between 30% and 100%.
Offshore matters can push the maximum to 200%. Within each band, your position depends on how much you tell HMRC, how quickly, and whether you volunteered it.
The same logic governs the assessment window. HMRC can go back four years for innocent errors, six for carelessness, and twenty where it can show deliberate behaviour.
That twenty-year reach is why arguing your behaviour was careless rather than deliberate often saves more than the penalty percentage itself.
What to Do in the First Fortnight
Acknowledge the letter and request an extension if you need one, because HMRC grants reasonable extensions when you ask. Preserve everything, including exchange CSVs, wallet addresses and old emails. Say nothing about figures until someone has reconstructed them, since an estimate you give in week one will follow you through the entire HMRC crypto enquiry.
Then get representation. An adviser who runs HMRC crypto enquiry cases weekly manages the correspondence, frames your behaviour accurately, and negotiates the penalty within the statutory bands. That framing is where most of the money is won or lost.
If HMRC has not contacted you yet and you know your reporting is wrong, the Digital Disclosure Service remains open. An unprompted disclosure attracts the lowest penalties available, and the window closes the moment HMRC writes to you.
Talk to Us Before You Reply
We handle HMRC crypto enquiries end to end: transaction reconstruction across exchanges and chains, disclosure drafting, COP8 and COP9 representation, penalty negotiation, and time-to-pay arrangements. A chartered certified accountant from our team leads every case, and every conversation stays confidential.
Book your consultation now. Call 0208 638 5800 or book your FREE first consultation online. The earlier you involve us, the more room we have to protect you.
People Also Ask
Can you go to prison for not declaring crypto in the UK?
Yes, but it is rare. Cheating the public revenue carries a maximum of life imprisonment, and fraudulent evasion of income tax up to seven years. HMRC settles the large majority of crypto cases civilly, with tax, interest and a penalty. It reserves prosecution for serious fraud, concealment or taxpayers who lie during an investigation.
Do I owe tax if I never cashed out to pounds?
Almost certainly yes. HMRC treats crypto as property, so swapping one token for another counts as a disposal, as does spending crypto or gifting it to anyone other than your spouse. Gains arise whether or not the money ever touches your bank account.
Can HMRC see my private wallet and DeFi activity?
Often, yes. Exchanges hand over the wallet addresses you withdrew to, and HMRC uses blockchain analytics to follow funds from there across chains and protocols. Self custody hides far less than most investors assume.
How long does an HMRC crypto enquiry take?
A straightforward enquiry usually closes within six to twelve months. Cases involving multiple exchanges, DeFi activity or Code of Practice 9 commonly run for one to two years. Producing a complete transaction history early is the single fastest way to shorten it.
Should I reply to an HMRC nudge letter myself?
Reply, but take advice before you do. A nudge letter carries a certificate you sign to confirm your tax position, and signing an inaccurate one hands HMRC evidence of deliberate behaviour. Get your figures reconstructed first, then respond.
