Test Compta Demat: Check Your FEC Before a Tax Audit

Receiving a tax audit notice is rarely the end of it: within fifteen days, the inspector will ask for your accounting entries file (FEC). If that file is rejected by their tools, the exchange starts badly and the risk of a penalty is immediate. The good news: the French tax authority (DGFiP) provides the very same control engine the inspector uses, the Test Compta Demat tool. Using it beforehand means reading the anomalies before they do.

Quick answer. Test Compta Demat is the DGFiP's free software that checks the structure and format of your FEC (encoding, separator, 18 mandatory fields). You import it, run the analysis, fix the blocking anomalies in your accounting software, then regenerate the file until you get a clean report.

The tool does not judge your tax position. It checks one thing only: whether your FEC is readable and compliant with the standard format set by article A47 A-1 of the French Book of Tax Procedures (LPF). In practice, it checks the file encoding, the separator character, the order and presence of the 18 mandatory columns, and the arithmetic consistency between debit and credit.

Presenting accounts in digital form is a legal obligation under article L47 A, I of the LPF: any company keeping its accounts through computerised systems must provide an FEC during an audit. Test Compta Demat is therefore not meant to replace your accountant, but to secure the form of the deliverable before it is handed over.

What the tool checks, and what it does not#

In other words, an FEC that passes Test Compta Demat with no anomaly is still a file whose content can be questioned during an audit. The tool deals with admissibility, not substance.

Here is the order to follow to move from a raw export to a clean file.

1. Download the tool from the impots.gouv.fr portal, in the accounting entries file section. Always take the latest version published by the DGFiP.
2. Generate the FEC export from your accounting software for the requested year. The file name follows the format SIREN, the FEC label, then the closing date (for example 123456789FEC20251231).
3. Import the file into the tool and launch the structure and format analysis.
4. Read the report, separating blocking anomalies from non-blocking warnings.
5. Fix at source, in your accounting software, never by hand in the exported file.
6. Regenerate then re-test until zero blocking anomalies remain, and archive the final dated report.

In practice: never edit the exported file by hand#

The temptation to open the file in a spreadsheet to repair a faulty line is strong. It is a false good idea. The FEC must reflect your accounts exactly: if you edit it outside the software, you create a gap between the file handed over and the trial balance, which the inspector can detect. The rule is simple: fix the entry in the software, re-export, re-test.

This is the heart of the exercise. The report distinguishes two families of anomalies, and the difference matters.

A single blocking anomaly is enough to make the file non-compliant within the meaning of the standard format. Conversely, an FEC can be accepted while piling up warnings: do not ignore them, because an empty label or a poorly structured journal draws attention to the substance.

A common case: the FEC generated by a homemade spreadsheet#

In start-up files or very small structures, the most common sticking point comes from accounts kept on a spreadsheet. The resulting file often comes out with a wrong separator, badly formatted dates or columns out of order. Test Compta Demat then returns a cascade of blocking anomalies. The reflex to favour is rarely to tinker with the export: it is to move to software that natively produces a compliant FEC, as Pennylane and its FEC export allow.

This is where caution is required, because a false idea circulates widely.

The penalty under article 1729 D, I of the French General Tax Code (CGI) sanctions the failure to present the FEC or its non-compliance. Since the update of the administrative doctrine on 15 December 2021 (BOI-CF-IOR-60-40-10), this penalty applies only once per audit, regardless of the number of years audited. The administration totals the reassessed tax across the entire audited period, then applies the penalty to that total.

The former position, which applied the penalty year by year, was abandoned at the end of 2021: beware of sources that still perpetuate it.

This scale is subject to the texts in force in spring 2026 and to the assessment of the audit services. For a specific case, the analysis of your situation always takes precedence over the general principle.

Our reading#

The real stake of Test Compta Demat is not the penalty, which is often avoidable, but the dynamics of the audit. An FEC that passes without a hitch sends a signal of seriousness to the inspector: the accounts are kept, exportable, mastered. A rejected file, by contrast, opens the audit on a note of distrust and wastes precious time in the very first days. In our bookkeeping and review work, we systematically test the FEC at closing, not only when the audit notice arrives.

The underestimated risk#

Many business owners think a market accounting software guarantees a perfect FEC. This is false in two frequent cases: exports from old versions or custom settings, and files reconstituted after a software change mid-year. The continuity of numbering and reconciliation is then often broken, generating warnings or even blocking anomalies. Testing each financial year, not just the last one, avoids the bad surprise.

Even with a technically compliant FEC, the inspector uses the file for its substance. They cross-reference journals, look for manual entries made at year-end, check the sequence of vouchers and the unalterable nature of validated records. A format-clean FEC does not exempt you from sound accounts on the merits. This is why technical self-checking must go hand in hand with a review, ideally with your accountant, to anticipate the topics an audit will raise.

• Test Compta Demat is the DGFiP's free tool that checks the structure and format of your FEC, not its tax substance.
• Providing an FEC is mandatory during an audit (article L47 A, I of the LPF); the standard format has 18 fields (article A47 A-1 of the LPF).
• A blocking anomaly makes the file non-compliant; non-blocking warnings do not prevent acceptance but must not be neglected.
• The penalty under article 1729 D, I of the CGI applies once per audit since the doctrine of 15/12/2021: 10% of total reassessed tax if >= EUR 50,000, otherwise EUR 5,000.
• Always fix in the accounting software, never by hand in the exported file.
• Testing the FEC at every closing, not just on receipt of a notice, is the best insurance.

• Software change mid-year: rebuild a continuous FEC over the full financial year, checking voucher numbering and reconciliation. This is the most frequent source of anomalies.
• Accounts kept abroad for a French subsidiary: the FEC must be produced in the French format, which often requires reprocessing. Our French CPA work covers this point for international groups.
• Mixed activity or several establishments: make sure the export consolidates all the entries of the legal entity, with no duplicate and no missing journal.