HMRC Is Asking About Years of Crypto Trades I Never Declared: Am I Facing Prosecution?

Does an HMRC Crypto Tax Enquiry Mean I Could Be Prosecuted?

Not necessarily. HMRC regularly contacts taxpayers where information suggests that cryptoasset income or gains may have been omitted from their tax returns.

A formal compliance check does not amount to a criminal charge. The nature of the investigation and the evidence of your conduct determine whether the matter could become criminal.

Understanding the difference between a civil enquiry and a fraud investigation

A civil compliance check may involve questions about your tax returns, requests for transaction records or assessments for unpaid tax. HMRC may also issue formal information notices requiring documents by a specified deadline.

A Code of Practice 9 (COP9) letter is different. It means HMRC suspects serious tax fraud and is offering the Contractual Disclosure Facility (CDF) as a route to resolving the matter through civil procedures.

Accepting the CDF requires you to admit deliberate behaviour and provide a full disclosure. In return, HMRC undertakes not to pursue a criminal investigation into the fraud properly disclosed under the agreement, provided its conditions are met.

A criminal investigation is a separate process. Fraudulent evasion of income tax requires proof of knowing involvement in fraudulent evasion beyond reasonable doubt.

How to identify which letter you have received

• A nudge letter usually invites you to check whether your cryptoasset transactions have been correctly reported.
• A formal enquiry letter identifies the tax return or period HMRC is examining.
• An information notice may legally require you to provide specified records.
• A discovery assessment states the additional tax HMRC considers payable and may carry appeal rights.
• A COP9 letter offers the CDF and requires a decision about whether to accept or reject it.

The wording matters because each process has different obligations and deadlines.

Check the response deadline before doing anything else

Read the letter carefully and establish when HMRC expects a response.

For COP9, the normal deadline is 60 calendar days from receiving the CDF offer. If you accept, a valid Outline Disclosure must also be submitted within that period. Other notices have their own deadlines, and some provide rights to appeal or request a review.

If you cannot gather the records in time, obtain advice about requesting an extension rather than submitting incomplete figures.

How Are Crypto Trades, Staking and DeFi Transactions Taxed?

HMRC generally applies existing Income Tax and Capital Gains Tax rules to cryptoassets. The tax treatment depends on the transaction, whether you received income and whether you disposed of an asset.

Crypto-to-crypto swaps

• Swapping Bitcoin for Ether, or one token for another, is normally a disposal for Capital Gains Tax purposes.
• You do not have to convert crypto into pounds for a taxable disposal to arise.
• The gain or loss is generally calculated using the sterling value of the transaction and the allowable cost of the tokens disposed of.
• HMRC’s pooling rules normally apply to tokens of the same type, with separate rules for acquisitions made on the same day or within 30 days of a disposal.

Staking rewards

• Staking rewards may be taxable as income when received, even if you do not sell the tokens.
• Their sterling value at receipt is generally relevant to the Income Tax calculation.
• If you later sell or swap the tokens, Capital Gains Tax may also apply to any subsequent gain.
• The precise treatment depends on how the rewards arose and whether your activities amount to a trade.

DeFi lending and liquidity provision

• DeFi transactions can be more complicated because the tax treatment depends on how the arrangement operates.
• For example, lending tokens to a protocol may create a Capital Gains Tax disposal if beneficial ownership passes to another party.
• If beneficial ownership remains with you, depositing the tokens may not itself be a disposal.
• Rewards or returns may be taxable as income or capital, depending on their nature.
• Each arrangement needs to be assessed using its terms and transaction records.

Transfers between wallets you control

• Moving tokens between wallets that you beneficially own is generally not a taxable disposal.
• However, you should preserve records showing that both wallets belong to you.
• Otherwise, transfers may be mistaken for sales, payments or new receipts during a tax reconstruction.

Airdrops and hard forks

• Airdrops received in return for services or through trading activity may be taxable as income.
• Where tokens are received without providing services and outside a trade, Income Tax may not arise on receipt, although a later disposal may create a Capital Gains Tax liability.
• Hard forks are treated differently. Where new tokens arise from an existing holding, allowable acquisition costs are generally apportioned between the original and new tokens.

Neither an airdrop nor a hard fork should automatically be treated as having a nil acquisition cost without checking the applicable rules.

Why losses must be assessed tax year by tax year

A large crypto loss in one year does not automatically cancel taxable gains from an earlier year. Capital gains and losses must be calculated for the relevant tax years.

Allowable losses may be carried forward against future gains, subject to the rules and reporting deadlines. This is why HMRC may still assess tax on historic gains even where your portfolio has since lost much of its value.

What Information Can HMRC Obtain From Crypto Exchanges?

HMRC can obtain records from crypto exchanges and use them to check whether transactions have been correctly declared. The information available may include account-holder details, transaction histories and payment records.

Routine reporting by UK-registered exchanges

UK cryptoasset businesses have obligations to verify customer identities and retain relevant records under anti-money laundering rules. HMRC can also obtain information through its statutory powers and international information-sharing arrangements.

Under the Crypto-Asset Reporting Framework, relevant service providers must collect transaction information for the 2026 calendar year, with the first reports due by 31 May 2027.

This expands HMRC’s access to cryptoasset transaction data.

Powers HMRC can use to compel information

HMRC can issue statutory information notices requiring taxpayers or third parties to provide relevant documents.

For example, investigators may request exchange records, bank statements or information explaining transfers between accounts. Failure to comply with a valid notice can result in penalties.

The information requested must fall within the applicable legal powers, and some notices or decisions may be challenged.

What this means for someone who assumed their crypto trades were private

HMRC may already hold information about trades you have not declared. However, an exchange record does not necessarily establish the correct tax liability.

Investigators still need to distinguish purchases, disposals, transfers between your own wallets and taxable receipts.

Your complete transaction history may therefore be important in explaining the information HMRC has obtained.

How to Reconstruct Crypto Records for a Tax Enquiry

Start by gathering records from every exchange and wallet you used during the years HMRC is examining. Organise the transactions chronologically and identify which records are missing.

Starting with exchange account exports

Download available transaction histories, including purchases, sales, swaps, fees, deposits and withdrawals. CSV exports may be useful because they can be combined into a single transaction history.

If an exchange has closed or removed older data, check whether account statements, confirmation emails or archived records remain available.

Using blockchain data to fill gaps

Public blockchain records can help verify wallet transactions, including dates, amounts and destination addresses. Block explorers may allow you to recover information missing from exchange records.

However, blockchain data does not always explain who controlled a wallet or why a transaction occurred.

Specialist crypto tax software can help organise records, but its calculations still need checking.

Obtaining sterling valuations for each transaction

Tax calculations generally require the sterling value of relevant transactions when they occurred. Historical market data may help establish those values.

Where a token was illiquid or prices varied significantly between exchanges, a consistent and reasonable valuation method is important.

Keep a record of the sources and assumptions used.

Documenting transfers between your own wallets

Identify transfers between addresses and accounts you beneficially owned. These should be distinguished from genuine disposals or receipts of income.

Keep records linking the wallets to you and showing where the assets moved.

Dealing with lost or inaccessible records honestly

If records cannot be recovered, explain what is missing and what steps you took to obtain them. Reasonable estimates may be necessary, but their basis should be documented.

Do not present estimated figures as confirmed transaction values. An accurate reconstruction is more useful than one that appears complete but relies on unsupported assumptions.

How Genuine Ignorance Affects Penalties and Any Criminal Assessment

A genuine misunderstanding of crypto tax rules may affect how HMRC assesses your conduct. However, not knowing the rules does not automatically remove the tax liability or prevent a penalty.

The civil penalty behaviour categories

For inaccuracies in tax returns, HMRC generally distinguishes between reasonable care, careless behaviour, deliberate inaccuracies and deliberate concealment.

An error made despite taking reasonable care may attract no inaccuracy penalty. Careless inaccuracies generally attract penalties of up to 30% of the lost tax, while deliberate behaviour can attract higher penalties.

The applicable rules also depend on whether you filed an inaccurate return or failed to notify HMRC of a liability. HMRC considers the available evidence and your cooperation when assessing penalties.

How ignorance affects the criminal threshold

A misunderstanding of the tax treatment of swaps, staking or DeFi may be relevant to whether you acted fraudulently.

For example, someone who recorded all their transactions but incorrectly believed crypto-to-crypto swaps were not taxable may be in a different position from someone who deliberately concealed accounts or falsified records.

However, claims of ignorance will be examined against what you knew, what advice you received and how you handled your tax affairs.

The prosecution must prove the mental elements of the particular offence beyond reasonable doubt.

Penalties, Tax Owed and What Criminal Sentencing Can Mean

Unpaid tax, interest, civil penalties and criminal sentences are separate consequences. A civil enquiry may result in additional tax and penalties without criminal charges.

Tax owed and statutory interest

• You remain liable for tax properly due on undeclared cryptoasset income or gains.
• HMRC generally charges late-payment interest from the relevant due date.
• The interest is normally calculated on a simple rather than compound basis.
• The amount depends on the tax outstanding, the period of non-payment and the applicable rates.

Civil penalties under Schedule 24

• For inaccurate returns, penalties depend on the behaviour involved and whether disclosure was prompted or unprompted.
• A disclosure made before HMRC has reason to investigate may qualify for greater reductions.
• If HMRC has already contacted you about the relevant crypto transactions, a later disclosure may be treated as prompted.
• Providing complete information and cooperating can still reduce penalties within the applicable rules.

Sentencing for criminal tax evasion

• Serious deliberate tax evasion can result in criminal prosecution.
• Fraudulent evasion of income tax carries a maximum sentence of fourteen years‘ imprisonment for offences committed from 22 February 2024.
• Cheating the public revenue carries a maximum sentence of life imprisonment, while fraud under the Fraud Act 2006 carries a maximum of ten years.
• The actual sentence depends on the offence, the amount involved and the defendant’s conduct.

An HMRC civil enquiry does not mean that any of these criminal penalties will apply.

Disclosure Routes Available After HMRC Has Made Contact

You may still be able to correct undeclared cryptoasset tax after receiving a letter from HMRC. However, the appropriate process depends on whether you are dealing with a routine compliance enquiry or suspected fraud.

The Cryptoasset Disclosure Facility

HMRC’s cryptoasset disclosure service allows taxpayers to report unpaid tax arising from cryptoassets. It can be used for historic liabilities that need correcting outside the normal Self Assessment process.

The disclosure must cover the relevant income, gains, tax years and supporting calculations. HMRC generally requires payment within 30 days of the disclosure. If you cannot pay, contact HMRC about the available options.

Using the facility does not guarantee immunity from criminal investigation.

The Contractual Disclosure Facility under COP9

A COP9 letter means HMRC suspects serious tax fraud and is offering the Contractual Disclosure Facility. Accepting requires an admission of deliberate conduct and a valid Outline Disclosure within 60 days of receiving the offer.

If you comply with the agreement, HMRC undertakes not to criminally investigate the fraud properly disclosed under its terms.

This is different from an ordinary cryptoasset disclosure and should not be accepted without understanding the admission involved.

Years the disclosure should cover

The relevant period depends on how the tax loss arose.

HMRC can generally assess up to six years where the loss resulted from carelessness, or twenty years for deliberate behaviour. Other rules apply to ordinary errors and certain failures to notify liability.

A disclosure should cover the years that can lawfully be assessed and any other relevant obligations. Do not restrict it to the most recent transactions without establishing the full position.

How a Specialist Solicitor Can Help

If HMRC is asking about years of undeclared crypto trades, a solicitor experienced in tax investigations can review the correspondence and explain whether you face a civil enquiry or suspected fraud investigation.

They can work with a crypto tax specialist to reconstruct transactions, assess potential liabilities and advise on the appropriate disclosure route.

Where criminal allegations are possible, a solicitor can also examine the evidence of your knowledge and intentions and advise before any interview.

Confidential communications made for the purpose of obtaining legal advice are generally protected by legal professional privilege, subject to legal exceptions. Ordinary accountancy advice does not automatically receive the same protection.

Our fraud and financial crime team advises individuals facing HMRC investigations and allegations involving undeclared cryptoasset transactions.

Speak to a solicitor about your HMRC enquiry and next steps.