Exchange closed or records lost? How to document your crypto basis

Before asking anyone for anything, list every place that might hold a trace of the acquisition. For each source write what it is, the period it covers, where it is stored and the date you checked it. A source that turns out to be empty is still worth a line, because it shows what you tried.

Even a closed or locked account usually leaves a record on the exchange's side. Ask in writing through support and keep the ticket number and date. Be specific: all fiat and crypto deposits, all withdrawals with destination addresses and transaction hashes, all trades and conversions, rewards, fees, the full date range, and the account identifiers. Ask for a CSV if you can.

If the account still opens, check what the exchange offers itself. Coinbase, for example, says account statements are available from the time the account was created, as monthly downloads in HTML, PDF or CSV, plus custom statements by asset, transaction type and date.

If you live in the EU or EEA and the exchange is subject to the GDPR, Article 15 gives you a right of access to the personal data the company holds about you and to a copy of it, and Article 12 sets a response time of one month, extendable by two further months for complex requests. The UK has a similar right. A written access request that names your transaction and account history is a reasonable step when ordinary support goes nowhere. This is general information, not legal advice.

If the exchange went through insolvency, any notices you received may name an administrator or claims portal. Those can hold customer account data, so check them and ask what records are available.

Withdrawal records usually name the destination address, and your own wallet history names the sending address of anything you deposited. You do not need to share an extended public key or any private key for this. Paste each address into a public block explorer for that network and read what it shows: amounts, times, counterparties and fees.

Match those movements to what you still have: an email confirmation with a hash, a bank transfer on the same day, a screenshot with an amount. The guide on finding the cost basis of crypto transferred from another exchange walks through matching both ends of a transfer.

Be careful with labels. An explorer shows that coins moved between addresses, not who owns an address. If you think an address belongs to an exchange but cannot prove it, record the link as unconfirmed.

For purchases made with fiat, bank and card statements can show the date and amount you sent. Ask your bank how far back it keeps statements, since older ones may need a request. Search your email for the exchange's name, for payment processor receipts and for tax forms.

These records prove that money left your account, not what it bought. To tie a transfer to a purchase you still need a trade record, a confirmation email or a wallet receipt for the same day. When only the bank side exists, document the acquisition as partly supported and say what is missing.

The IRS FAQs say taxpayers must keep records sufficient to establish the positions on their returns. For a lost-records case that means a file your preparer can follow: what was recovered, how each piece links to a lot, and what is still open.

Label every lot by how strong its evidence is: confirmed by a source record and a linked transfer, supported by indirect evidence such as a bank transfer plus an explorer match, or unresolved. Keep a log of every request: date, who you asked, ticket number and the reply. Do not fill a gap with a guess, a zero, or a market price nobody can trace.

What happens when a lot cannot be proven is a question for your tax professional. Your part is to hand over the evidence, the log and an honest open-items list.

If one closed exchange gave you a usable export, the steps above and your tax software are usually enough. When the exchange gives you nothing, the trail runs through several wallets, or the evidence is split across banks, emails and exports, the work is tracing and documenting. See the synthetic sample Evidence Pack for what a reviewed result looks like, and Coinbase 1099-DA shows no cost basis if the immediate problem is a blank basis on a form.

BasisRestore reviews qualified cases and prepares an Evidence Pack with a source map, reconciled ledger, decision log and open-items list. The free no-upload check tells you whether your case fits. BasisRestore does not give tax advice or file returns, and never asks for seed phrases, private keys, exchange passwords or withdrawal-enabled API keys.