My client’s exchange no longer exists, how do I reconstruct that history?

How do you reconstruct crypto history when the exchange no longer exists?

You reconstruct the history by using the on-chain route as a replacement for the missing export file: every deposit to the exchange and every withdrawal from it is a transaction on the blockchain, with date, amount and addresses. Around those fixed points the rest of the history is built up from documents your client still has.

An exchange export file is in fact a summary of two kinds of data. The first part concerns what went into and out of the platform; that part is also on the chain. The second part concerns what happened within the platform, such as purchases with euros, swaps between coins and internal transfers; that part was only in the platform’s own records. If the platform disappears, the first part therefore remains, and that is where the effort to reconstruct crypto history begins.

The substantive framework for this work can be found on the page about proving the origin of assets. That page explains how substantiation is structured; this blog is about the part of the history that is missing when a platform disappears.

Which sources remain when the export file is missing?

When the export file is missing, five sources generally remain, and together they cover a large part of the history. We map them in a fixed order, so that each source is checked against the others.

1. The chain: deposits and withdrawals between the exchange and your client’s wallets, with transaction hash.
2. Bank statements: the euro transfers to and from the exchange, with date and amount.
3. Confirmation emails: notifications of purchases, deposits and withdrawals the platform sent at the time.
4. Earlier overviews: old exports, annual statements or tax returns in which the crypto holdings were included before.
5. Data from the wind-down: if the platform stopped under a trustee or in a wind-down, the data provided to customers in that process.

That last source differs greatly per platform. Under the European regulation on crypto-assets, providers must have a plan for an orderly wind-down of their activities, which shows that they can stop without causing undue economic harm to their clients (ESMA, MiCA Article 74). For platforms that stopped years ago, that obligation did not yet apply, and there the chain is often the only source that has remained complete.

The term on-chain stands for exactly this distinction: data recorded on the blockchain itself, separate from a platform’s records.

What does the chain show and not show?

The chain shows which amounts were moved between the exchange and your client’s wallets and when, and does not show what happened to those amounts within the exchange. That distinction determines which parts of the history are established and which parts are substantiated with additional documents.

A withdrawal to an own wallet is easy to recognise on the chain. The amount arrives at an address your client controls, from an address belonging to the exchange, and the timing coincides with the confirmation email from that time. A deposit in the opposite direction can be linked in the same way. This produces per period a balance of what went into the platform and what came out.

The difference between the two is the part that stayed within the platform or was converted there. The report states per period which part was established on the chain and which part relies on emails, statements or earlier overviews.

The limit. Transactions outside the blockchain, such as cash payments or internal bookings within an exchange, are not visible in blockchain data. They are only included if underlying documents are available.

Case. A tax adviser had to substantiate for a client the purchases of coins bought years earlier through an exchange that had since stopped. The client had no export, only a series of old emails and the bank statements from those years.

On the chain, three withdrawals from the exchange to a wallet of the client could be found, each on the day of a confirmation email. The bank statements showed the euro transfers to the exchange in the weeks before. This made it possible to establish per withdrawal which deposit preceded it. For one period an email was missing; there the report stated explicitly that the link relies on amount and timing and not on a confirmation from the platform. The adviser could thus indicate per year what was established and where an assumption lay.

How does the reconstruction fit into your tax file?

The reconstruction fits into your file because it shows per year and per reference date which holdings there were and what they rely on, so that you as adviser can make the tax qualification on established facts. That qualification remains with you; the report provides the factual substantiation.

That distinction becomes more important now that data on crypto-assets is being exchanged between tax authorities. The European rules for that exchange apply from 1 January 2026, and the first reporting on that year follows in 2027 (European Commission on DAC8). For the years before that there is no report from a provider, and a vanished exchange will not make one either. For those years, the only way to obtain substantiation is to reconstruct crypto history.

The report follows a fixed structure, including the data supplied, the sources consulted, the findings per component and a chronological overview. Not every report contains all components; in a historical reconstruction the emphasis is on the chronological overview. Which party prepares an overview for the tax return and what belongs in it can be read on the question page which party sets out crypto assets for the tax return.

How long does a reconstruction take and what does Paucitas deliver?

Reconstructing crypto history for a vanished exchange falls within Paucitas’ normal lead times and, because of the missing history, often results in a more extensive file. Paucitas delivers a report stating the source for each transaction, so that in your file you can refer to an established line instead of an estimate.

A Paucitas investigation takes between one working day and two weeks, depending on the size of the file and the urgency. An urgent report can be delivered within one working day and in exceptional cases the same day. A regular investigation is usually ready within three working days. For files with many transactions, several wallets or missing history, the lead time rises to around two weeks. A surcharge applies to urgent assignments.

Data is supplied digitally or at the office. Per case a delivery list is provided which states what data is needed. Where necessary Paucitas guides the collection and delivery of that data.

How we work with advisers is described on the page for accountants and advisers. If you want your client’s history reconstructed, Paucitas first assesses which sources still exist and what can be established with them; see source of funds. Which other documents belong in a tax file can be read in the related blog tax file: the documents you really need. For a specific file, contact Paucitas.