Preparing for a French Crypto Tax Audit
The fear of a crypto examination is mostly a fear of not being able to explain yourself. That is the right thing to be afraid of, and it is also the part you can fix in advance, because an examination is a request for evidence rather than a debate about the law.
What an examination actually asks
Strip away the anxiety and the questions are narrow:
- What did you hold, where, and over what period?
- Which events did you treat as taxable, and why those?
- How did you compute each gain, and can you reproduce it?
- Where does the money in your bank account come from?
- Did you declare the accounts you were required to declare?
Every one of those is answerable from records. None is answerable from memory.
The three positions that need documenting in advance
1. Which events you treated as taxable. For private investors, a taxable event arises only on conversion to fiat, spending crypto, or receiving crypto as income. Crypto to crypto exchanges are not taxable. That is favourable, and precisely because it is favourable you should be able to show that the events you excluded really were crypto to crypto and not something else.
2. Whether you are a private investor at all. If your activity is professional, or if you mine, profits fall under the BNC regime at the progressive income tax scale up to 45%, with a different treatment altogether. On that side, the micro-BNC option (a 34% allowance) is available below 77,700 euros of turnover, a threshold our France crypto tax guide states and which should be confirmed with the DGFiP. The line between an active private investor and a professional is a factual assessment, and it is far easier to document your position while trading than to argue it three years later.
3. Your cost computation. France applies a proportional method across the whole portfolio of digital assets, where each disposal is computed against the total acquisition price of the entire portfolio and its value. That calculation cannot be reproduced without complete data, so a partial history is not a partial answer, it is no answer.
The bank statement problem
A large proportion of crypto examinations begin with a bank credit rather than with a blockchain. An unexplained transfer into your account is a question, and answering "that was crypto" only helps if you can show which disposal it corresponds to, when the asset was acquired, and at what cost.
The chain of evidence runs backwards from the bank line to the exchange withdrawal, to the disposal, to the acquisition. Every gap in that chain is a place where an assumption unfavourable to you can be made.
Do not forget the separate declaration
Formulaire 3916-bis, the declaration of digital asset accounts held abroad, is an obligation independent of your gains, filed one per account. It carries a fixed penalty per undeclared account irrespective of whether tax was due. In practice, undeclared accounts are among the most common findings, because people who correctly declared their gains often never knew the account declaration existed.
What to assemble now
- Complete history from every venue, exported while the accounts still exist.
- Bank statements matched to exchange deposits and withdrawals in both directions.
- Portfolio wide acquisition data, which is what the proportional method needs.
- Your Formulaire 2086 filings with each disposal listed, and the 2042 C carrying the result.
- A written note of your positions, dated: why you treated events as you did, made contemporaneously rather than reconstructed.
- Your 3916-bis filings, one per foreign account.
What not to do
- Do not answer from memory or estimate under pressure. A figure you cannot support is worse than asking for time.
- Do not move assets or close accounts once an examination is under way.
- Do not volunteer reconstructions that are not evidenced.
- Do get professional representation. Examination procedure has its own rules and deadlines, and a conseiller fiscal or avocat fiscaliste is the right party to deal with them.
The general point: the flat tax is 30% on 2025 gains and rises to approximately 31.4% for 2026, so verify the rate for your year. But the rate is rarely what an examination turns on. It turns on whether your numbers can be reproduced.
Our Formulaire 2086 guide covers the declaration, and French crypto tax covers the framework.
General information, not tax advice. Rules change and depend on your circumstances. Confirm the current position with the relevant tax authority or a qualified tax professional.
FAQ
What you held, where and over what period; which events you treated as taxable and why; how each gain was computed and whether it can be reproduced; where bank credits came from; and whether you declared the accounts you were required to declare. All of it is answerable from records rather than memory.
Because an unexplained credit into your account is the visible end of the chain. Answering that it was crypto only helps if you can show which disposal it corresponds to, when the asset was acquired and at what cost. Every gap in that chain is a place where an unfavourable assumption can be made.
Undeclared foreign accounts. Formulaire 3916-bis is an obligation independent of your gains, filed one per account, with a fixed penalty per undeclared account irrespective of whether tax was due. People who declared their gains correctly often never knew it existed.
Do not answer from memory or estimate under pressure, do not move assets or close accounts once it is under way, and do not volunteer unevidenced reconstructions. Get representation, since examination procedure has its own rules and deadlines.