Cerfa 2086 Common Errors

Form 2086 is short, which lulls filers into errors that the DGFiP — armed with DAC8 data from 2026 — now catches systematically. Every error below produces a divergence between the declared figure and the reconstructed/reported reality, which is exactly the audit entry point. This guide is the seven recurring mistakes and how to avoid each.

TL;DR — the seven errors

1. FIFO instead of 150 VH bis (the single biggest one).
2. Omitting the portfolio-value input for each disposal.
3. €305 misapplied (as a deduction / per-transaction / partial).
4. Declaring crypto-to-crypto as taxable (it is not, for occasional investors).
5. Stale 30% PFU instead of 2026's 31.4%.
6. Assuming the €305 exemption was abolished (it was not — still in force).
7. Forgetting Form 3916-bis (independent of 2086, costly).

1. FIFO instead of the 150 VH bis method

The most frequent and most consequential error. France does not use FIFO, LIFO, or per-lot cost basis for occasional investors. Article 150 VH bis applies a global-portfolio proportional formula (see crypto capital gains calculation):

Gain = disposal price − ( total acquisition price × disposal price / total portfolio value )

A 2086 computed with FIFO is wrong on every line, not just at the margin. Most generic crypto tax tools default to FIFO; using a FIFO export verbatim in the French 2086 is the classic mistake. Confirm the tool is set to the French 150 VH bis method.

2. Omitting the portfolio-value input

Each 2086 disposal line needs the global portfolio value at the moment of that disposal — not just the value of the asset sold. Filers routinely enter the disposal price and an acquisition figure but omit or guess the portfolio value, which breaks the proportional formula. Without an accurate portfolio valuation at each disposal date, the 150 VH bis result is unreliable. This is why manual 2086 computation is impractical for active investors.

3. Misapplying the €305 threshold

Three sub-errors, all common (see the France €305 exemption):

Measuring the threshold on gains (instead of disposals) or treating it as partial relief are the two that most often produce a wrong return.

4. Declaring crypto-to-crypto as taxable

For occasional investors, crypto-to-crypto exchanges are not taxable events — only conversions to fiat, goods, or services are (see France crypto tax guide). Declaring BTC→ETH or ETH→USDC as taxable 2086 lines overstates the tax and signals a misunderstanding the DGFiP may probe (it suggests the rest of the computation may also be off-method). Crypto-to-crypto must be tracked (it affects portfolio valuation) but is not a taxable 2086 line.

5. Using the stale 30% PFU

A 2026-specific trap. The PFU rose from 30% to 31.4% on 1 January 2026 (CSG on capital income up from 9.2% to 10.6%; prélèvements sociaux 17.2% → 18.6%; total 12.8% + 18.6% = 31.4%). A 2026 return computed at 30% / 17.2% under-states the tax — and is exactly the kind of stale-figure error that recurs because tools and older guides lag. Use 31.4% for 2026 (see PFU vs barème).

6. Assuming the €305 exemption was abolished

The mirror error to #3. Some outdated guidance states the €305 exemption was removed "from 2023." It was not — it remains in force under article 150 VH bis I in 2026 (total annual disposals ≤ €305 → fully exempt). Wrongly believing it was abolished leads filers to compute and pay tax on a year that was actually exempt. Confirm the current rule, not stale commentary.

7. Forgetting Form 3916-bis

Not strictly a 2086 field, but the most expensive co-occurring mistake. Filers under €305 correctly skip the 2086 computation, then wrongly conclude they have nothing to file — and miss Form 3916-bis, which is independent of 2086 and of the €305 threshold and carries a €750/€1,500-per-account penalty regardless of any tax due. With DAC8 surfacing foreign accounts from 2026, this omission is now reliably detected.

The pattern behind all seven

Every error produces a declared-vs-reality divergence — wrong method, wrong base, wrong rate, or a missing form. From 2026, DAC8/CARF give the DGFiP the reconstructed reality automatically (see DGFiP crypto audit). The defence is the same for all seven: a 150 VH bis-correct, 31.4%-rate, €305-correct, 3916-bis-complete return that reconciles to the reported data.

Practical pre-filing checklist

1. Tool set to 150 VH bis, not FIFO.
2. Portfolio value captured at each disposal date.
3. €305 measured on total disposals, all-or-nothing.
4. No crypto-to-crypto on taxable lines (occasional investor).
5. PFU at 31.4% for 2026 (not 30%).
6. €305 exemption treated as in force (not abolished).
7. One 3916-bis per foreign account — always.

How vendor tools handle these errors

Waltio (French-specialised) is built around the 150 VH bis method and the €305/PFU logic; Koinly supports the French method as a setting. The recurring failure is a generic FIFO export pasted into the 2086 — confirm the French method, the 31.4% rate, the all-or-nothing €305, and that foreign accounts are listed so the 3916-bis is not missed.

How Wag3s helps

Wag3s Folio computes the 150 VH bis method with portfolio valuation at each disposal, applies the all-or-nothing €305 test and the 2026 PFU 31.4%, excludes crypto-to-crypto from taxable lines, and lists foreign accounts for the 3916-bis — eliminating the seven errors by construction and reconciling against DAC8-reported data. See the Folio product page.

Further reading

• Cerfa 2086 Explained
• Crypto Capital Gains Calculation France (150 VH bis)
• The France €305 Exemption
• PFU vs Barème: Choosing in France
• Cerfa 3916-bis — Foreign Crypto Accounts
• DGFiP Crypto Tax Audit

Sources

• Article 150 VH bis CGI (global-portfolio method; €305 threshold at 150 VH bis I) — Légifrance
• 2026 CSG increase on capital income (9.2% → 10.6%) raising the PFU from 30% to 31.4%
• Article 1736 X CGI (3916-bis penalty)
• Council Directive (EU) 2023/2226 (DAC8) — EUR-Lex