Box 3 and crypto: the most frequently asked verification questions

How does HMRC treat crypto?

For most individuals, Capital Gains Tax can apply when you sell, exchange, spend or give away crypto and make a gain. HMRC expects you to keep your own records of each transaction, including the type of token, the date, the amount, the value in pounds and the pooled cost. That is set out on the GOV.UK page on tax when you sell cryptoassets.

Which HMRC crypto questions come up most often?

In our experience, it usually comes down to five questions:

1. Which crypto did you hold, and where was it?
2. When did you sell, swap or spend it, and for how much?
3. What did it cost you, and how did you work out the pooled cost?
4. Do your figures match what the platform reported?
5. Where did the money you started with come from?

Each question looks simple. But anyone with several wallets, who moved crypto between their own addresses or has to go back years, soon finds the answer gets complicated.

Received a letter with questions? Let Paucitas take a look with you. You can ring us any time, 24/7, on +31 20 244 5774.

What information do you need?

Usually four kinds: your wallet addresses, annual or balance statements per exchange, the transaction hash of key bookings, and a price source for each relevant date. Together they make each disposal checkable and the origin of your assets traceable.

Missing records, for example because a platform no longer exists? That happens a lot. Bank statements, your inbox and the blockchain itself are still there. Together they often make the picture convincing after all.

What if you lost access to your crypto?

Then it matters what can be established: which addresses were involved, what moved and from when you could no longer use it. How that is treated for tax is a question for your adviser.

Paucitas will never ask for your recovery phrase or private key of its own accord. If you want to regain access to your own wallet, we guide you through it without needing to see that information ourselves.

What changes with the new reporting rules?

Under the Cryptoasset Reporting Framework, UK crypto platforms collect details of their users and their transactions from 1 January 2026 and pass them to HMRC. HMRC can put that information next to your return. An overview that matches it prevents questions later. The EU equivalent is DAC8.

Who helps with HMRC crypto questions?

Paucitas. We work everything out for you: the transactions, the disposals, the route of the money and the documents. Paucitas also reads through your emails, messages and other communication with platforms, so the full picture emerges with a timeline of where the money came from and where it went, step by step. Paucitas does all tracing itself, without tracing tools. You receive an asset verification that anyone can follow and understand step by step, including your adviser.

• No tax advice: Paucitas provides the evidence; your return is done by you or your adviser.
• Costs: every investigation is tailored. You receive a quote in advance that we go through together, with no surprises.
• Turnaround: from the same day to around two weeks.

Further reading: frequently asked questions about asset verification and a proof of origin file for your bank.

Want to know what you are still missing? Get in touch for a free intake, or ring +31 20 244 5774. Via the form you will hear from us within 1 to 3 hours.

Sources: GOV.UK, check if you need to pay tax when you sell cryptoassets; HMRC, implementation of the Cryptoasset Reporting Framework.