DGFiP Crypto Tax Audit in France

The number that matters in a French crypto audit is not the rate — it is the reassessment period. The DGFiP normally has 3 years. But the crypto fact patterns that most holders fall into — never declaring habitual activity, omitting a foreign exchange account — flip that to 10 years. With DAC8 delivering CASP data from 2026, the detection that used to be unlikely is now systematic. This guide is the procedure, the triggers, and the defence file.

TL;DR

• Standard reassessment period: 3 years (délai de reprise, article L. 169 LPF).
• Extends to 10 years for: undeclared activity (habitual trading, structured mining, regular NFT sales), an omitted foreign crypto account, or a sham foreign domicile.
• Audit entry point: declared (2086/2042 C) vs reconstructed/reported reality.
• DAC8/CARF from 2026 make declared-vs-reported divergence and omitted accounts systematically visible.
• Defence = a reconcilable history: every figure on the return reproducible from records.

The 3-year default — and why crypto often loses it

For a correctly-declared occasional investor, the DGFiP's reassessment window is 3 years from the declaration year. That is the routine case. The problem is that crypto holders disproportionately fall into the situations that extend it to 10 years:

Any one of these converts the comfortable 3-year window into a 10-year exposure. The 3916-bis omission is the most common — and it is independent of whether tax was even due (see Cerfa 3916-bis). Treating "I didn't owe tax" as "I have no exposure" is the classic error: the omitted-account trigger is about disclosure, not tax owed.

What the DGFiP actually checks

A crypto contrôle fiscal is, at its core, a reconciliation:

• Declared position: Form 2086 / Form 2042 C lines 3AN/3BN.
• Reconstructed reality: from wallet addresses, exchange statements, on-chain analysis, and — from 2026 — DAC8/CARF automatic data.

Within that, the examiner tests:

1. The 150 VH bis computation (correct portfolio method, not FIFO — see crypto capital gains calculation).
2. The €305 threshold application (all-or-nothing, on disposals — see the France €305 exemption).
3. Foreign-account declarations (3916-bis completeness).
4. Whether activity should have been BNC (professional trading or staking/mining income) rather than only PFU (see BNC vs PFU).

The single most common finding is a divergence between the declared net and what the reconstructed/reported data shows — which is exactly what DAC8 hands the DGFiP from 2026.

DAC8/CARF: detection becomes systematic

Before 2026, the DGFiP largely depended on the taxpayer's declaration plus ad hoc data requests. From 1 January 2026, DAC8 (EU CASPs) and CARF (non-EU) deliver automatic, structured, multi-year data on French residents' crypto activity (see DAC8 impact on individuals). Two consequences for audits:

• Declared-vs-reported divergence is now a default flag, not a needle to find.
• Omitted foreign accounts surface directly — and that omission is itself a 10-year trigger.

The pre-2026 strategy of relying on non-detection is structurally over. The audit question is no longer "will they find it" but "does your declared position reconcile to what they already have."

The defence file

The only durable defence is a reconcilable history. The DGFiP expects you to reproduce every declared figure on request; if you cannot, the burden of proof shifts against you for the rest of the audit. A defensible file contains:

• Every acquisition and disposal: euro value, date, counterparty/venue.
• The running total acquisition price (the 150 VH bis cumulative figure) across all years.
• Portfolio valuations at each disposal date.
• All wallet addresses and exchange statements.
• The 3916-bis filings for every foreign account.
• The BNC-vs-PFU classification rationale where relevant.

Build this before an audit, not during. Reconstruction under a 15-day production demand, across years and venues, is where unprepared holders lose.

If you have undeclared prior years

Given the 10-year window and DAC8 detection, the rational move for a holder with undeclared prior years is to consider a voluntary regularisation before the first DAC8 cross-check materially raises detection probability. This is a national-tax-law decision — take advice from a French tax lawyer on the mechanism and the penalty exposure (the corrective declaration is generally better than a discovered omission).

Practical guidance

1. Assume the 10-year window applies if you ever had undeclared activity or an undeclared foreign account.
2. Build the reconcilable history now — every figure reproducible.
3. Reconcile your declarations against DAC8/CARF-reported data each year from 2026.
4. Fix prior omissions via voluntary regularisation with counsel, ahead of the cross-check.
5. If audited, engage a French tax lawyer immediately — do not respond to the DGFiP unrepresented.

How vendor tools help audit-readiness

Waltio (French-specialised) and Koinly reconstruct history and produce 2086-consistent figures — the basis of a reconcilable file. Confirm the tool uses the 150 VH bis method and the 2026 PFU 31.4%, and that it lists foreign accounts so 3916-bis omissions are caught before the DGFiP catches them. Tools build the file; they do not handle the audit — that is a French tax lawyer.

How Wag3s helps

Wag3s Folio maintains a continuously reconcilable multi-chain history — every declared figure reproducible from records — and flags foreign accounts and BNC-side income, so a holder is audit-ready before a contrôle and can reconcile against DAC8/CARF-reported data. See the Folio product page.

Further reading

• France Crypto Tax Guide 2026
• Cerfa 3916-bis — Foreign Crypto Accounts
• Crypto Capital Gains Calculation France (150 VH bis)
• BNC vs PFU for Crypto in France
• DAC8 Impact on Individuals
• Crypto Audit Readiness — general framework

Sources

• Article L. 169 LPF (Livre des procédures fiscales) — reassessment period (3 years; 10 years for occult activity / undeclared foreign accounts) — Légifrance
• DGFiP — audit practice for digital assets; 3916-bis omission as a 10-year trigger
• Council Directive (EU) 2023/2226 (DAC8) — EUR-Lex