When a crypto exchange closes, start by collecting evidence from outside the platform: bank statements, trade confirmation emails, wallet records and previous downloads. Together, these can help rebuild the history needed for your UK tax return.
The exchange’s closure does not remove your record keeping responsibilities. HMRC specifically recognises that exchanges may disappear before someone completes a return and places responsibility for keeping transaction records on the individual.
Your aim is to establish what happened, support the figures with evidence and clearly identify anything that remains uncertain.
1. Preserve any records you can still access
If account access remains available, download your full history immediately. Include completed trades, deposits, withdrawals, fees, rewards and cash balances. Check whether separate exports are needed for different account sections.
Save original files unchanged and use copies for calculations. Screenshots can support your records, but downloadable transaction files are usually easier to reconcile.
If access has ended, contact the exchange’s verified support channel or appointed administrator. Request your complete account ledger, execution history and closing balances. Keep copies of requests and replies.
An administrator’s statement may confirm what you are owed without showing how you acquired it. It is useful evidence, but may not replace the transaction history.
2. Gather evidence from other sources
Search your email, downloads, cloud storage and old devices. Look for completed trade confirmations, account statements, withdrawal notices and files previously shared with an accountant.
Build an evidence folder containing:
- Bank statements showing payments to and from the exchange.
- Emails confirming executed trades and fees.
- Wallet addresses and transaction hashes.
- Earlier transaction exports and tax calculations.
- Administrator statements and account balance screenshots.
Bank statements establish cash movements, but a deposit into an exchange does not prove that a purchase happened immediately.
Likewise, an order confirmation may only show that you placed an order. Check whether it was filled, partially filled or cancelled.
A useful approach is to list each missing period, the evidence available and what you still need to obtain.
3. Use blockchain records to trace transfers
For transactions recorded on a public blockchain, a blockchain explorer can help confirm dates, quantities, addresses and network fees. Start with wallet addresses and transaction hashes you can connect to your own records.
However, blockchain evidence has limits. Trades carried out within an exchange’s internal system may not appear as individual blockchain transactions. A deposit followed by a withdrawal cannot reveal every purchase or swap between those events.
Match transfers using the asset, network, amount, timing and transaction reference. Allow for fees when quantities differ.
Moving tokens between wallets while retaining beneficial ownership is not itself a disposal for Capital Gains Tax. Mark these movements correctly so they are not mistaken for sales or new income.
Use public addresses for this work; private keys and recovery phrases are unnecessary.
4. Create one transaction ledger
Bring the evidence into a spreadsheet or accounting record. Give each transaction a reference and record:
- Date, time and original time zone.
- Transaction type, such as purchase, sale, swap or transfer.
- Assets and quantities sent and received.
- Transaction value in pounds sterling.
- Fees and the currency used to pay them.
- Supporting filename, trade reference or transaction hash.
- Whether the entry is confirmed, reconstructed or unresolved.
For swaps, capture both the asset given up and the asset received. Preserve original timestamps and document any time zone conversion, particularly around midnight and the UK tax year end.
Remove duplicates carefully. One transaction may appear in an email, wallet export and exchange statement.
Then reconcile each asset: opening units plus receipts, less outgoings and separately charged token fees, should explain the closing units. A negative balance or unexplained difference is a reason to investigate, not invent a balancing trade.
5. Rebuild purchase costs across all accounts
Do not calculate tax using only the failed exchange’s records.
For an individual investor, tokens of the same type are generally pooled across their holdings, rather than separately for each exchange. Disposal calculations apply same day matching first, then relevant acquisitions during the following 30 days, before drawing on the section 104 pool.
This means earlier purchases elsewhere may affect the allowable cost of a later sale. Start from reliable opening pool balances or trace acquisitions far enough back to reconstruct them.
For example, evidence that you deposited £2,000 and later withdrew £2,600 does not establish a £600 taxable gain. You might have retained tokens, made intermediate swaps or received rewards.
Interface Accountants’ cryptocurrency taxation service provides specialist advice when missing records affect your tax calculations.
6. Reconstruct sterling values without hiding uncertainty
Use actual transaction values where available. If a trade was recorded in another currency, retain the original amount and document the historical conversion into pounds.
Where historical market pricing is needed, record the source, timestamp and method. Match the valuation as closely as the evidence allows to the transaction concerned. Do not use today’s price to fill an old gap.
HMRC requires transaction values in pounds sterling at the transaction date and supporting records for valuations.
Keep uncertainty visible. “Date confirmed; fee unavailable” tells your accountant more than an apparently complete entry containing an unexplained estimate.
Missing paperwork does not automatically establish that the acquisition cost was zero. Investigate supporting evidence before accepting a calculation that treats the entire disposal proceeds as a gain.
7. Deal with remaining gaps before filing
If you cannot recreate every record, HMRC allows provisional or estimated figures, with disclosure in the return’s “Any other information” section.
Provisional figures are used when confirmation is expected later. Estimated figures are used when you cannot obtain confirmation. Explain which figures are affected, why records are missing and how you calculated the amounts. Estimates must have a reasonable basis; they are not permission to choose a convenient result.
Do not simply delay filing while waiting for the exchange. Discuss unresolved gaps before the deadline through tax return support.
Also separate missing records from inaccessible funds. An exchange closure does not automatically justify recording a capital loss. Whether relief applies depends on the asset or rights held and the circumstances. HMRC’s negligible value rules for pooled tokens concern the whole pool.
Frequently Asked Questions
Can bank statements replace my exchange history?
They support cash deposits and withdrawals, but usually cannot show token quantities, internal swaps, rewards or trading fees. Combine them with other evidence.
Can transaction software recover every missing trade?
No. Software can organise available data, but it cannot reliably recreate internal exchange trades without underlying records. Review missing costs and unmatched transfers manually.
What if I recover the records after filing?
Review the return and correct affected figures. You can normally amend a Self Assessment return within 12 months of the statutory filing deadline. After that, contact HMRC about the appropriate correction route.
Should I include transactions where no pounds reached my bank?
Yes. Exchanging one cryptoasset for another can be a taxable disposal, even when you never withdraw cash.
What should I give my accountant?
Provide original evidence, the reconstructed ledger, previous tax calculations, opening pool balances and a clear list of unresolved entries.
Build a history you can explain
A reliable reconstruction connects transactions to evidence, reconciles balances and makes uncertainty visible. Recover the records first, check the calculations across all your holdings, then address any remaining gaps openly.
Going forward, download records regularly and keep independent backups alongside your running acquisition costs. Your next tax return should depend on records you control, rather than whether an exchange remains available.