HMRC cryptoasset letter help
Use the deadline and questions stated in your letter. Bring the relevant exchange and wallet history together, calculate under UK matching rules, and keep every material gap visible before deciding how to respond.
ChainTax prepares reviewable calculations; it is not a tax adviser. A letter can make deadlines, behaviour, penalty, and disclosure-route decisions professionally sensitive.
Letter refers to Coinbase? Follow the Coinbase evidence checklist.
Use the date, deadline, questions, and contact details printed on the letter you received.
Every relevant exchange, wallet, acquisition, disposal, and income source can affect the answer.
Reconciliation, amendment, disclosure, and adviser-led responses are not interchangeable.
Possible response paths
The cards below are orientation, not a decision tree. The correct route depends on the year, the filed return, the amount, the taxpayer’s behaviour, and what HMRC has asked.
Figures reconcile
Retain the calculation and supporting records, then answer the questions in the letter by its stated deadline. A tax adviser can help confirm that the response addresses the actual wording.
Calculate and preserve the evidenceCorrection needed
The appropriate route may be an amended Self Assessment return, depending on the year and circumstances. Do not assume a disclosure service is always required.
Review the HMRC guidanceEarlier years or material exposure
Multiple years, large amounts, uncertain behaviour, company activity, trading status, or deliberate conduct need professional advice before choosing the route or penalty treatment.
Review the safe next stepsSafe next action
Keep the letter and its deadline, identify the years and accounts it refers to, preserve the relevant exchange and wallet records, and avoid confirming figures until the history has been reconciled. The three routes below have different scopes.
ChainTax can combine supported personal exchange and EVM-wallet history, apply its documented UK calculation rules, show unresolved evidence, and prepare reviewable working. It does not submit an HMRC response.
Check supported historyChainTax does not give tax advice, legal advice, penalty advice, or representation. Seek an appropriately qualified adviser when the route, behaviour category, amendment position, disclosure period, ownership, company activity, or material exposure is uncertain.
Concierge can arrange the next step for supported data preparation or calculation help. It does not manage an HMRC case, select the response, or replace professional tax advice. Keep ordinary first-contact email limited to broad scope and deadline information.
Scope software help safelyHMRC Cryptoasset Disclosure Service
HMRC’s service is for voluntary disclosure of unpaid tax on cryptoassets. The official guidance asks you to gather the source information, calculate the tax, interest, and applicable penalties, submit the disclosure, then use the payment reference HMRC provides.
HMRC currently says payment is due within 30 days of submitting the disclosure. It does not describe the cryptoasset route as a “Cryptoasset Disclosure Facility” or create a generic 90-day registration window.
Prompted versus unprompted
HMRC describes an unprompted disclosure as one made when the person has no reason to believe HMRC has discovered, or is about to discover, the issue. Contact from HMRC can therefore be highly relevant. The classification depends on the specific facts.
Read HMRC’s prompted-disclosure guidanceWhat ChainTax can prepare
Supported Coinbase, Binance and Kraken; Crypto.com App (beta); plus Koinly universal CSV (compatible format) imports plus public wallets across five EVM chains.
Same-day, 30-day bed and breakfasting, and Section 104 pooling in the required order.
34 protocol-specific classifiers, with unresolved activity left visible.
PDF, CSV, SA108-oriented totals, income, fees, confidence, price sources, and per-disposal Show Working.
Start with an adviser when the decision is the risky part
Company crypto, trading or mining as a business, large undeclared amounts, deliberate conduct, offshore issues, disputed ownership, or uncertainty about how far back to disclose should not be routed through a self-serve marketing funnel. ChainTax can support the calculation after the adviser defines the scope.
CARF timeline
In-scope cryptoasset service providers began due diligence, record keeping, and data collection on 1 January 2026. Reports for the first period, covering 1 January to 31 December 2026, are due to HMRC by 31 May 2027.
Read HMRC’s confirmed CARF commencementCARF is context, not a threat claim
The practical point is to keep exchange and wallet records capable of explaining the same economic activity. It is not accurate to imply that every provider began streaming transaction data to HMRC in January 2026.
See the CARF readiness guideThese are calculation boundaries, current-law choices, and coverage gaps to review before relying on a report.
Full detail: How it works → Important boundaries
Questions
Read the exact questions and deadline in the letter. Preserve the letter, gather the exchange accounts and wallets relevant to the years it mentions, and avoid confirming figures until you have reconciled the source history. Different HMRC letters can ask for different responses.
Do not assume a universal deadline. Use the date and response instructions printed on your own letter. If the deadline is close or has passed, contact a qualified tax adviser or HMRC using the details in the letter.
No. ChainTax can calculate supported personal exchange and DeFi activity, show evidence gaps, and prepare report working. It does not decide whether a disclosure is prompted, select a behaviour or penalty category, give legal advice, or submit the response for you.
HMRC calls it the Cryptoasset Disclosure Service. It is used to tell HMRC about unpaid tax on cryptoassets for earlier periods. Current or previous-year amounts may instead belong on a Self Assessment return; the right route depends on the facts.
Prompted status is fact-specific. HMRC guidance says a disclosure is unprompted only where the person has no reason to believe HMRC has discovered or is about to discover the issue. Contact from HMRC can therefore be highly relevant, and the position should not be assumed from marketing copy.
In-scope providers began due diligence, record keeping, and data collection from 1 January 2026. The first reports covering the 2026 calendar year are due to HMRC by 31 May 2027. That does not mean every provider sent a live data feed to HMRC in January 2026.
Check the history here if this is supported personal exchange and DeFi activity. Start with a specialist adviser if the response route, behaviour, company status, or material exposure is uncertain.