The article in brief
- The tax authority can match your Form 2086 and Form 3916-bis returns against data sent by platforms, including DAC8 data from 2027.
- An undeclared foreign wallet costs a €750 fine, raised to €1,500 if its value exceeded €50,000 during the year.
- The tax reassessed bears late-payment interest of 0.20% per month and a surcharge: 40% for a deliberate failure, 80% if the crypto-assets were held in an undeclared foreign wallet.
- The ordinary reassessment period runs until the end of the third year following the tax year.
- It rises to ten years for income linked to an undeclared foreign wallet.
- A voluntary amended return reduces late-payment interest by 50%, subject to conditions.
A crypto tax reassessment arises from a gap between what you declared and what the tax authority knows. Its sources are multiplying: Form 3916-bis returns, reports by French platforms and European exchanges of information under DAC8. If tax is reassessed, you pay the evaded tax, late-payment interest and, depending on your conduct, a surcharge. Fines are added for each undeclared foreign wallet. Regularising before any audit costs less.
Facts and sources verified as at 5 October 2026.
How the French tax authority detects your crypto-assets
A crypto tax audit relies on several information flows. They reach the tax authority through different channels and become stronger from 2027.
Your own Form 3916-bis returns
Article 1649 bis C of the French Tax Code (CGI) requires you to declare each year your crypto-asset wallets opened, held, used or closed abroad. The declaration is filed with your income tax return, on Form 3916-bis. It reveals the existence of your accounts to the tax authority. If these accounts match no declared gain over several years, the gap may attract attention.
Reporting by platforms since 2026
Article 1649 AC bis of the CGI transposes the DAC8 directive. It requires crypto-asset service providers to report their users’ transactions. It covers transactions carried out from 1 January 2026, with a first report in 2027.
The report contains your identity, your tax number if available and your residence. It details your exchanges and transfers for the calendar year. Our article on DAC8 crypto describes this system in detail.
Exchanges between European tax authorities
DAC8 amends Directive 2011/16/EU on administrative cooperation. Each Member State sends the others the information received from its providers. The transmission takes place within nine months of the end of the calendar year. A platform established elsewhere in the Union does not therefore put you out of reach.
What you risk in a crypto tax reassessment
A reassessment adds up several items. Each one is governed by its own text.
The evaded tax
For an individual, gains on crypto-assets fall under Article 150 VH bis of the CGI. They bear an overall rate of 31.4%: 12.8% income tax and 18.6% social levies. Social levies are audited and collected with the same penalties as income tax, under Article L. 136-6 of the French Social Security Code (Code de la sécurité sociale).
The tax authority may also challenge the classification of your gains. If your transactions resemble those of a professional, it may tax them in another category. We deal with this point in our article on the professional crypto trader.
Surcharges
Article 1729 of the CGI penalises inaccuracies or omissions found in a return. The surcharge reaches 40% for a deliberate failure. It rises to 80% for abuse of law, fraudulent manoeuvres or concealment of part of the price stipulated in a contract. Where the reassessment concerns crypto-assets in an undeclared foreign wallet, Article 1729-0 A of the CGI (in French) applies an 80% surcharge. It cannot be lower than the fine under Article 1736, X, and excludes the surcharges under Articles 1728, 1729 and 1758.
Article 1728 of the CGI covers another situation: a return filed late. The surcharge is 10% in the absence of a formal notice. It rises to 40% if the return is still missing thirty days after a formal notice, and to 80% in the case of a concealed activity.
Late-payment interest
Article 1727 of the CGI applies late-payment interest to any tax debt paid late. Its rate is 0.20% per month. For income tax, it runs from 1 July of the year following the year for which the tax is assessed. It stops on the last day of the month of payment. It does not depend on your good faith: only the late payment counts.
Fines for an undeclared foreign wallet
Article 1736, X, of the CGI sets a fine of €750 per undeclared wallet. Each omission or inaccuracy costs €125, capped at €10,000 per return. These amounts rise to €1,500 and €250 if the value of the wallets exceeded €50,000 at any time during the year. These fines apply even if you made no gain.
A worked example
Take a numerical example, purely for illustration. In 2025, you made a gain of €10,000 on a foreign platform. You filed your income tax return on time, but without Form 2086 or Form 3916-bis. The reassessment concerns crypto-assets in a wallet that should have been declared, and you pay after 24 months of late-payment interest.
- Evaded tax: €10,000 × 31.4% = €3,140.
- 80% surcharge (Article 1729-0 A of the CGI): €3,140 × 80% = €2,512.
- Late-payment interest: 24 months × 0.20% = 4.8%, i.e. €150.72.
- Fine for the undeclared wallet: €750.
The total reaches €6,552.72, for initial tax of €3,140. A second undeclared platform would add €750. A value above €50,000 would double each fine.
Four mistakes to look for in your returns
The mistakes below can arise from a simple misreading of the rules. Spot them before the tax authority does, while voluntary regularisation remains open.
- Not attaching Form 2086 because the year’s disposals remain below €305. The form is nevertheless required in that case.
- Carrying a loss forward to the following year. Article 150 VH bis only sets it against gains of the same year.
- Forgetting an account closed during the year. Form 3916-bis also covers wallets closed abroad.
- Declaring a gain equal to the sale price. The statutory formula deducts a fraction of the portfolio’s total acquisition price.
How far back can the French tax authority go?
The reassessment period sets the time during which the tax authority can adjust your tax. For income tax, Article L. 169 of the French Tax Procedure Code (Livre des procédures fiscales, LPF) sets it at the end of the third year following the tax year. For a gain made in 2025, the tax authority can act until 31 December 2028.
This period rises to ten years where you have not complied with the obligation under Article 1649 bis C of the CGI. For the same 2025 gain, linked to an undeclared foreign wallet, the period runs until 31 December 2035. The extension only covers income linked to the reporting obligations not complied with.
The text provides for an exception where the total of foreign accounts did not exceed €50,000 during the year. This exception concerns the bank accounts under Article 1649 A of the CGI. It does not cover crypto-asset wallets, whatever their amount.
Regularising before or during an audit
Voluntary regularisation remains the least costly route. In our view, it deserves to be considered as soon as you identify an omission, without waiting for the first DAC8 transmissions.
Before any audit
Article 1727, V, of the CGI reduces late-payment interest by 50% in the case of a voluntary amended return. You must file it before the reassessment period expires. The text also requires payment of the tax, or a payment plan accepted by the public accountant. The regularisation must not concern an offence “exclusive de bonne foi” (inconsistent with good faith).
During an audit
Article L. 62 of the Tax Procedure Code opens a second possibility during an audit. The time limit runs in particular from a request for information or a proposed tax reassessment (proposition de rectification). You ask to correct your errors, omissions or understatements, then file a supplementary return within thirty days. You pay the tax and late-payment interest reduced to 70% of its amount.
This mechanism has two limits. It only applies to returns filed on time: a return never filed does not qualify. Nor must the offence be “exclusive de bonne foi” (inconsistent with good faith).
These reductions apply to late-payment interest. We recommend that you also quantify your exposure to the fines under Article 1736, X, before filing anything.
The lawyer’s role in a crypto case
A regularisation case starts with an inventory. Every platform, every wallet and every taxable disposal over the period not yet time-barred must be traced. Exported histories may be incomplete, and the formula in Article 150 VH bis requires the overall value of the portfolio at each disposal.
A crypto tax lawyer reconstructs this data, recalculates the gains and prepares the amended returns. The lawyer then assists you in exchanges with the tax authority if an audit opens. Every situation is different: the holding period, the number of accounts and your good faith change the strategy.
For the substantive rules, our guide to crypto taxation covers the calculation of gains, the thresholds and the forms.
FAQ on crypto tax audits in France
Can the tax authority audit my crypto-assets if I have never sold anything?
Yes, as regards your reporting obligations. A foreign wallet must be declared each year, even without a disposal. Omission exposes you to the fine under Article 1736, X, of the CGI, i.e. €750 per wallet, or €1,500 above €50,000.
How many years can a crypto reassessment cover?
In principle, until the end of the third year following the tax year. The period rises to ten years for income linked to an undeclared foreign wallet, under Article L. 169 of the Tax Procedure Code.
Does voluntary regularisation remove all penalties?
No. Article 1727, V, of the CGI reduces late-payment interest by 50%, subject to conditions of good faith and payment. The tax remains due. The other penalties must be examined case by case.
Does DAC8 apply to my past transactions?
Article 1649 AC bis of the CGI covers transactions carried out from 1 January 2026. Earlier years can still be audited within the reassessment periods, based on the other information available to the tax authority.
Official sources
- Article L. 169 of the French Tax Procedure Code (Livre des procédures fiscales) (reassessment period) – Légifrance (in French)
- Article L. 62 of the French Tax Procedure Code (Livre des procédures fiscales) (regularisation during an audit) – Légifrance (in French)
- Article 1727 of the French Tax Code (Code général des impôts) (late-payment interest) – Légifrance (in French)
- Article 1728 of the French Tax Code (Code général des impôts) (failure to file or late filing) – Légifrance (in French)
- Article 1729 of the French Tax Code (Code général des impôts) (inaccuracies or omissions) – Légifrance (in French)
- Article 1736 of the French Tax Code (Code général des impôts), X (Form 3916-bis fines) – Légifrance (in French)
- Article 1649 bis C of the French Tax Code (Code général des impôts) (wallets held abroad) – Légifrance (in French)
- Article 1649 AC bis of the French Tax Code (Code général des impôts) (reporting by providers) – Légifrance (in French)
- Article L. 136-6 of the French Social Security Code (Code de la sécurité sociale) (contribution on investment and property income) – Légifrance (in French)
- Council Directive (EU) 2023/2226 of 17 October 2023 (DAC8) – EUR-Lex
- Impots.gouv.fr, overall rate of 31.4% on gains on crypto-assets (page updated on 17 July 2026) – impots.gouv.fr (in French)
This article sets out the law verified as at 5 October 2026 for general information purposes. It does not constitute legal advice. Every situation is different and deserves a dedicated analysis.
