Build records HMRC can test
Build one evidence trail for each crypto event. You can then show where every tax figure came from.
Keep the source files, not just reports
Keep the original CSV export from every exchange. Keep account statements, order confirmations and bank statements too.
A crypto tax report can help calculate gains. But it is a summary, not the receipt behind the summary.
| Keep this | What it proves | Typical source |
|---|
| Original transaction export | Trades, fees and timestamps | Exchange CSV |
| GBP payment record | Money entering or leaving the platform | Bank or card statement |
| Blockchain transaction | Wallet-to-wallet movement | Blockchain explorer |
Separate your duty from an exchange’s duty
Your duty to keep records remains separate from any records an exchange provides.
Collect proof for each crypto activity
Create folders by tax year and transaction type. Missing evidence then becomes visible quickly.
Log purchases, sales and swaps
Save the exchange CSV, trade confirmation and order ID for every event. Save the timestamp, asset pair, quantity, GBP value and fee too.
A Bitcoin-for-Ether swap can be a disposal for UK Capital Gains Tax. This applies even when no pounds reach your bank.
Prove transfers between your own wallets
Record the sending address, receiving address, txid and asset amount. Record the network fee and matching exchange withdrawal or deposit reference.
A txid is the unique blockchain reference. Think of it as a parcel tracking number.
A transfer between wallets you own is not normally a taxable disposal by itself, but both sides of the transfer must be documented.
Match the amount sent with the amount received. Allow for the network fee and confirmation delay.
Capture income, DeFi and NFT evidence
Use an activity-by-activity evidence checklist. Do not treat all receipts as ordinary trades.
For a purchase or sale, retain the crypto trade confirmation and order ID. Keep the GBP value, fee and payment record.
For crypto-to-crypto swaps, save both asset quantities. Save the valuation source at the time of the swap.
For staking, mining, airdrops and DeFi income, keep the platform statement. Keep the reward date, time, quantity, GBP value and wallet transaction ID.
For NFTs, preserve the marketplace listing and sale or purchase confirmation. Keep the token ID, royalty or marketplace fees, wallet address and blockchain transaction evidence.
Keep network fees separately when they relate to a disposal, acquisition or own-wallet movement.
Reconcile CSVs, wallets and bank payments
Match every bank payment, exchange entry and on-chain movement in date order. This prevents duplicated trades.
Match cash to each exchange account
Match every GBP deposit and withdrawal on your bank statement. Link it to an exchange, card payment or payment provider.
Use the date, amount, reference and account name. Allow between 1 and 3 working days for card settlement.
Match exchange flows to the blockchain
Audit evidence path for one transaction
Bank payment
date and amount
Exchange CSV
trade ID and fee
Wallet record
address and txid
Tax ledger
GBP gain or income
Link the calculation to the evidence
Use one row per event in an audit ledger. Then link each row to the saved files.
This separates a plausible report from one HMRC can check.
| Ledger field | Evidence to link | Common failure |
|---|
| Date, time, asset and quantity | CSV or wallet history | Date without timestamp |
| GBP value and price source | Trade confirmation or dated price record | No saved valuation evidence |
| Cost, proceeds and fees | Calculation and source transaction | Fee omitted from calculation |
| Own-wallet transfer | Both addresses, txid and exchange record | Counted as sale and purchase |
Reconcile in a fixed order. First, place every exchange CSV export into one master cryptocurrency tax ledger.
Standardise dates, asset symbols, quantities and fees. Next, match each GBP deposit, withdrawal or card charge to its exchange account.
Use the amount, reference and settlement date. Then match exchange withdrawals and deposits to on-chain records.
Use the address, transaction ID and exchange withdrawal reference.
Mark a movement as an internal transfer only after documenting both addresses as controlled by you.
Investigate unmatched rows instead of deleting them. They may show missing trades, failed deposits, conversions, rewards or duplicated imports.
Repair gaps and answer HMRC clearly
Reconstruct missing history now. Your assumptions will then be visible before HMRC asks questions.
Rebuild unavailable exchange records
Save account-opening emails, trade confirmations and bank statements. Save deposit and withdrawal emails, old screenshots, wallet histories and blockchain explorer pages.
Ask the provider for a personal-data copy or transaction history. Save your request and its reply.
Prepare a measured HMRC response
⚠️ Do not alter original CSV files or screenshots. Work from copies, and preserve the original download date and filename.
When HMRC asks questions, first identify the tax years, transactions and tax heads in the request. Then prepare a dated chronology before sending documents.
Respond to the points asked. Use a working copy of the cryptocurrency tax ledger.
Link each figure to its source file, GBP valuation, calculation and any assumption. Keep original exchange exports, screenshots and blockchain records unchanged.
Maintain a separate index showing what you supplied and when.
If you rebuilt records after an exchange closure, explain the missing period. Explain the alternative evidence and method used.
A focused, consistent response is stronger than unlabelled files. It is also stronger than revised figures without an audit trail.
Common questions
How does HMRC know about my crypto?
HMRC can obtain crypto information through exchange data, bank records and international information sharing. It can also ask questions about your finances.
Keep evidence even if no letter has arrived. An enquiry can cover earlier tax years.
What records does HMRC require for crypto?
HMRC needs records for each crypto transaction, GBP value, fees, cost and tax treatment. Keep CSV files, statements, bank evidence, wallet addresses and txids.
Keep the calculations used for Self Assessment too.
How do I track Bitcoin transactions for tax?
Export records from every exchange and list every wallet address. Match each movement to bank and blockchain evidence.
Record timestamps, GBP valuations and fees. Then identify transfers between wallets you control.
Are wallet transfers taxable in the UK?
Transfers between wallets owned by the same person are not normally taxable disposals in the UK. Keep both addresses, the txid and related exchange records.
This stops the transfer being mistaken for a sale.
What if my crypto exchange has closed?
Rebuild the history using emails, bank statements, withdrawal records and blockchain data. Use dated screenshots too.
Document each missing period and each assumption. Seek specialist help if material figures remain uncertain.
How long should I keep crypto tax records?
Most Self Assessment taxpayers should keep crypto tax records for at least five years after the 31 January filing deadline. Keep them longer if HMRC opens an enquiry.
Keep them longer when asset history is needed for future disposals.
- Lo esencial: retain original exports and statements, not only software reports or wallet balances.
- Lo esencial: prove own-wallet transfers with both addresses and the transaction ID.
- Lo esencial: link every GBP tax figure to its price source, fees and source document.
- Lo esencial: record missing data and assumptions openly before replying to HMRC.
Related sources
These articles can help you explore the topic in more depth:
