HMRC Crypto Nudge Letter: What It Means & How to Respond

The two flavours of nudge letter

HMRC currently sends two distinct letters about crypto:

• Generic crypto-holder letter: “We’re aware you may have invested in cryptoassets... please review whether you should declare any tax due.” This is a fishing expedition based on broad data sharing — they don’t necessarily have specific evidence. Still serious, but less urgent.
• Specific-evidence letter: “Our records indicate transactions on [exchange name] during [tax year]. Please confirm whether the resulting gains/income have been declared.” This is more pointed — they have a specific data drop and they want you to confirm or correct your filings.

Both require a response. Ignoring is the worst possible move.

The 30-day clock

Most HMRC letters give you 30 days to respond. You have three legitimate paths:

1. Confirm everything is already declared. If you filed Self Assessment correctly with your crypto on the SA108, simply write back confirming so. Reference the tax years and the SA108 line totals.
2. File a missing return / correct an earlier one. If you should have filed and didn’t, register for Self Assessment and file the return. If you filed but missed crypto, amend within the 12-month amendment window (or use Digital Disclosure for older returns).
3. Use the Digital Disclosure Service / Worldwide Disclosure Facility. The cleanest way to declare multiple years of missed tax. We cover this in the next section.

You can request more time — HMRC almost always grants 30 more days if you state you’re calculating the tax. Don’t just go silent.

The Digital Disclosure Service (DDS)

For declaring tax you should have paid in earlier years, HMRC’s online DDS is the standard route. The process:

1. Notify your intent on the DDS portal. You then have 90 days to file the actual disclosure.
2. Calculate tax owed for each year — gains, income, interest, penalties.
3. Submit the disclosure with the calculation.
4. Pay the agreed amount.

Penalty bands for voluntary disclosure are typically 0–30% of the tax owed (depending on whether the omission was “careless” or “deliberate”) compared to up to 200% if HMRC opens an enquiry first. Doing this voluntarily is night-and-day for the financial outcome.

What the penalties actually look like

Plus interest from the original due date until paid (currently ~7.75% p.a. but variable).

Reconstructing missing data

The hardest part of responding to a nudge letter is often piecing together what you actually did across multiple years. Where to look:

• Exchange CSVs: Coinbase, Binance, Kraken all let you export your full history. Get this BEFORE your access expires.
• On-chain history: Etherscan / Solscan show every transaction your wallet ever did. CryptoLens reads this directly — paste your wallet, get a multi-year history in one click.
• Old emails: exchange withdrawal confirmations, tax forms (1099 from US exchanges), KYC docs — all useful evidence.
• Failed exchanges (FTX, Celsius, Voyager): claim creditor portals or Chainalysis reports if you have them.

Don’t do these things

• Don’t lie. “Deliberate concealment” jumps your penalty band by 20–70 percentage points and opens criminal exposure.
• Don’t move funds offshore mid-investigation. HMRC can apply Connect (their data-matching system) to track this.
• Don’t guess the numbers. If your records are gone, reconstruct from on-chain history or get an accountant to do it. Random estimates that turn out to be wrong worsen your position.
• Don’t use US-style tax tools blindly. Their cost basis methods (FIFO/LIFO/specific identification) don’t apply in the UK — pooling rules do.