HMRC Crypto Nudge Letter Help

What the letter means

An HMRC crypto nudge letter asks you to check your tax position. It does not, by itself, establish that you owe extra tax. A formal enquiry or investigation is different, so start by identifying what HMRC has actually sent and which years and activities it covers.

Read the whole letter, note its reference and response date, and keep a copy. If you are unsure whether it is genuine, check the contact details against GOV.UK before sharing personal information or paying anything.

Identify the type of contact

A nudge letter generally invites you to review your records and correct any omissions. Work to the date stated in your letter rather than assuming all crypto letters have the same deadline.

A formal enquiry may ask specific questions about a return or require information under a particular procedure. The scope and wording matter. A letter mentioning Code of Practice 9 or the Contractual Disclosure Facility concerns suspected fraud and requires professional advice. Do not treat it as an ordinary nudge letter or assume a routine crypto disclosure deals with it. [1]

Gather the evidence before giving a substantive answer

Collect exchange exports, wallet addresses and transaction histories, bank statements, previous tax returns and any earlier calculations. Include staking, lending, liquidity pools and other DeFi activity where relevant. Record transfers between your own wallets so that the same movement is not mistaken for a sale or new income.

Prepare a timeline of the activity and HMRC correspondence. Identify missing records and explain any reconstruction or valuation assumptions. Do not present an unsupported estimate as a verified figure. Crypto calculations need sterling values and the relevant matching and pooling treatment, not simply the profit displayed by one exchange. [2]

If you cannot complete the work by the response date, contact HMRC promptly to explain and request more time. Do not assume an extension has been granted. Keep a record of what HMRC agrees.

Prompted and unprompted disclosure

HMRC's test considers what you had reason to believe when you made the disclosure: had HMRC discovered, or was it about to discover, the relevant issue? A disclosure is unprompted only if you had no reason to believe that was the case. Contact about the same issue can be important evidence, but the scope of the contact and surrounding facts matter. [3]

Disclosures during a compliance check are usually prompted, although an unrelated matter outside its scope can be different. Taking advice before replying can help you make an accurate and complete disclosure; it does not itself preserve unprompted status. The date of an ordinary reply does not automatically fix the classification. [3]

Tax interest and penalties

The tax calculation, interest and any penalty are separate questions. An inaccurate return and a failure to notify HMRC can fall under different penalty rules. Behaviour, the applicable regime and the quality of disclosure matter; a single percentage table cannot describe every crypto case. [4]

Provide an accurate account of what happened and the steps you took. Do not assume that receiving a letter automatically means deliberate behaviour, or that appointing an adviser guarantees a lower penalty. If you believe your affairs are correct, explain that position with the relevant evidence rather than making a disclosure of tax you do not owe.

Choose the appropriate correction route

The next step may be a return, an amendment or a disclosure. HMRC's cryptoasset disclosure guidance directs current and previous tax-year income and gains to Self Assessment. For older unpaid crypto tax, its dedicated disclosure service may be relevant. An existing investigation or wider issues can affect the appropriate route. [5]

Read our voluntary-disclosure guide for the preparation involved: crypto voluntary disclosure. Tell your adviser about all HMRC contact before submitting anything through a separate facility.

Where the letter identifies omissions across several tax years, use our backdated crypto tax returns guide to organise the filed returns, missing years and records before choosing a correction route.

CARF and HMRC information

UK reporting cryptoasset service providers must report their first calendar-year 2026 information between 1 January and 31 May 2027. This provides HMRC with additional information to compare with returns. It does not automatically establish tax due or determine whether every disclosure is prompted. [6]

Getting help with a response

Professional help may be useful where several years, incomplete records, DeFi activity or a formal investigation are involved. An adviser can assess the letter, reconstruct the figures and explain the available response routes.

To ask about an introduction, use our enquiry form. We review enquiries before sharing them with our accountancy partner where appropriate. The firm decides whether to accept the work and agrees its fees with you. Submitting an enquiry does not extend an HMRC deadline.

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This guide is for general information only and does not constitute tax advice. Tax rules change and individual circumstances vary. Always consult a qualified tax adviser before making decisions about your tax position. Nothing on this website creates a professional relationship.

Sources

Last reviewed: 14 September 2026.

• [1] Code of Practice 9
• [2] Selling cryptoassets and keeping records
• [3] HMRC CH403202 prompted and unprompted disclosure
• [4] HMRC penalty guidance and disclosure reductions
• [5] Tell HMRC about unpaid tax on cryptoassets
• [6] Reporting cryptoasset user and transaction data

HMRC material is available under the Open Government Licence v3.0.

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