Crypto Tax Records: What HMRC Expects You to Keep

If you buy, sell, swap or earn crypto in the UK, HMRC expects you to keep a clear record of every transaction — not just a screenshot of your portfolio. This is a plain-English guide to what those records look like and why they matter. It's general information, not personal tax advice.

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Why records are your problem, not the exchange's

HMRC generally treats crypto as property rather than money, which means many things you do with it — selling, swapping one coin for another, spending it, sometimes earning it — can be taxable events. To work out what (if anything) you owe, you need an accurate history of everything you did. That history is your legal responsibility as the taxpayer, even if a piece of software or an accountant does the heavy lifting.

It's tempting to assume your exchange keeps perfect records for you. In practice it usually doesn't — at least not in the form HMRC wants. Exchanges track activity on their own platform, but they don't see your hardware wallet, your DeFi positions, or the coins you moved to a competitor. For the bigger picture on the rules these records feed into, see our overview of crypto taxes in the UK.

Where exchange data falls short

• It only covers activity on that one exchange — not transfers in or out, or anything on-chain.
• It may not show the GBP value at the exact time of each transaction, which is what HMRC actually needs.
• Platforms close, get acquired, or restrict access — and old data can vanish or become hard to export.
• Free CSV exports are often incomplete, missing fees, internal transfers or 'dust' amounts.
• It rarely applies the UK's specific pooling and matching rules for you.

What HMRC expects you to record

For each transaction, HMRC's guidance points to keeping enough detail to reconstruct exactly what happened and what it was worth in pounds at the time. The table below is a practical checklist of the fields worth capturing. The single trickiest one is the GBP value at the moment of the transaction — that's what your gain or loss is calculated from.

Earned crypto needs extra detail

When you earn crypto rather than buy it — through staking, mining, some airdrops, or being paid in tokens — there are usually two figures to capture, not one. First, the GBP value when you received it (often relevant for Income Tax). Second, that same value becomes your acquisition cost for any later disposal (relevant for Capital Gains Tax). Logging both at the time saves a lot of guesswork later.

• Staking and mining rewards — record the date, quantity and GBP value of each reward as you receive it. See what is staking and our note on crypto staking and mining tax in the UK.
• Airdrops — log when they landed and their value at that point; how they're treated can vary. Background in what is an airdrop.
• DeFi and NFTs — these can generate frequent, fiddly events; keep granular records. See what is DeFi and what is an NFT.

How long to keep records — and the cold-wallet trap

HMRC expects you to keep records for a set number of years after the relevant filing deadline, and longer if a return is late or under enquiry. Because the exact period can change, check the current figure on HMRC's site rather than relying on a number you read somewhere. The safe instinct is to keep more, for longer, and to back it up.

A practical wrinkle: if you move coins to cold storage and don't touch them for years, the record of what you paid and when can drift out of reach by the time you eventually sell. Whatever system you use to store Bitcoin safely, keep the acquisition details with it — your future self will need them to calculate a gain.

Building a record-keeping system that survives

You don't need anything fancy — you need something consistent. A simple, repeatable routine beats a perfect spreadsheet you abandon after a month. The steps below outline an approach that holds up over several tax years.

1. List every exchange, wallet and platform you've ever used — including ones you've stopped using.
2. Export full transaction history from each as soon as you can, in the most complete format available.
3. Capture the GBP value at the time of each transaction, plus fees, rather than only the coin amounts.
4. Store everything in at least two places (for example a cloud folder and a local backup).
5. Reconcile periodically so gaps and mismatches surface while they're still fixable.
6. Keep the records safely for the period HMRC currently specifies — check their site for the exact length.

Doing this by hand across multiple platforms is where most people come unstuck. Tax software is built to automate exactly this: it imports your history, fetches historic GBP prices, tracks fees and reconciles transfers between your own wallets. Once your records are in order, the same data feeds straight into working out your capital gains and, ultimately, filing your Self Assessment.

Frequently asked questions