The 18 FEC columns and the 10 errors that fail a French tax audit

Vincent — Sun, 01 Nov 2026 12:20:33 +0000

Every French company that keeps its books on a computer must be able to hand the tax administration one file: the FEC, Fichier des Écritures Comptables. Accounting software exports it in one click, so everyone assumes it is correct.

It often isn't. A FEC that is late or does not follow the required format costs a €5,000 fine under article 1729 D of the French tax code (CGI). For a remote audit (examen de comptabilité), the administration's own guidance, updated in January 2026, applies it once per audit (BOI-CF-DG-40-20 § 390). Worse than the fine, a file the auditor cannot read is a bad start to an audit.

This guide lists the 18 columns, then ten errors I see in real exports, each with a bad line, why it fails and the fix. Every example below comes from synthetic files and from the output of two checkers I wrote; the rules are checked against the official text.

What a FEC is

Since 2014, a company under audit must hand over its accounting entries as a file at the start of the audit (article L47 A of the Livre des procédures fiscales, LPF). For a remote audit, it has 15 days from the notice. The format is fixed by article A47 A-1 LPF and explained in the administration's guidance BOI-CF-IOR-60-40-20.

The file holds every entry recorded during the fiscal year, opening balances included, one line per entry line. Most companies send a flat text file; an XML format also exists, but this guide covers the flat file.

The 18 columns

For a company taxed on commercial profits (BIC or corporate tax), the file has exactly these 18 columns, in this order. Cash-basis non-commercial and agricultural filers add columns (22 and 21); they are out of scope here.

#	Column	Content	Example
1	JournalCode	Journal code	`VE`
2	JournalLib	Journal name	`Ventes`
3	EcritureNum	Entry number, on a continuous sequence	`000039`
4	EcritureDate	Accounting date, `AAAAMMJJ`	`20250610`
5	CompteNum	Account number	`411000`
6	CompteLib	Account name	`Clients`
7	CompAuxNum	Sub-ledger account (customer, supplier); may be empty	`CLI001`
8	CompAuxLib	Sub-ledger account name; filled when 7 is	`Atelier Durand`
9	PieceRef	Supporting document reference	`F2025-06`
10	PieceDate	Document date, `AAAAMMJJ`	`20250610`
11	EcritureLib	Entry label	`Facture F2025-06 Atelier Durand`
12	Debit	Debit amount, decimal comma	`3960,00`
13	Credit	Credit amount, decimal comma	`0,00`
14	EcritureLet	Matching (lettrage) code; may be empty	`AA`
15	DateLet	Matching date; filled when 14 is	`20250712`
16	ValidDate	Date the entry was validated	`20250610`
17	Montantdevise	Amount in foreign currency; may be empty	`1200,00`
18	Idevise	Currency code; filled when 17 is	`USD`

A full line looks like this (pipe-separated):

VE|Ventes|000039|20250610|411000|Clients|CLI001|Atelier Durand|F2025-06|20250610|Facture F2025-06 Atelier Durand|3960,00|0,00|||20250610||

If your software has no separate debit and credit, the text allows Montant and Sens (D/C or +1/-1) instead of columns 12 and 13. Most exports use Debit/Credit.

The 10 errors

1. Wrong file name

FEC_2025.txt

Why it fails: the name is part of the format: the company's SIREN, the letters FEC, then the fiscal year's closing date as AAAAMMJJ (A47 A-1, IX).

Fix: 123456782FEC20251231.txt for SIREN 123456782 and a year closing on 31 December 2025. The text fixes the name, not the extension; .txt is the usual choice for the flat file. Also check that the SIREN is right: it has a Luhn check digit, so a typo is often detectable.

2. Mixed or wrong separator

VE|Ventes|000002|20250310|411000|Clients|||F000002|20250310|Facture F1|120,00|0,00|||20250310||
VE;Ventes;000002;20250310;706000;Prestations;;;F000002;20250310;Facture F1;0,00;120,00;;;20250310;;

Why it fails: fields are separated by a tab or a pipe (|), the same one for the whole file (A47 A-1, VI). Semicolons, the default of many spreadsheets in France, are not allowed. The second line above has 1 field instead of 18 for a pipe reader, so the checker reports field_count on line 5, and the entry then looks unbalanced because half of it cannot be read.

Fix: export the FEC from the accounting software, never through a spreadsheet. If you must edit it, save as "text (tab-separated)" and check that no label contains the separator.

3. Broken accents

VE|Ventes|000002|20250310|411000|Clients|||F000002|20250310|Facture rÃ©glÃ©e|120,00|0,00|||20250310||

Why it fails: the allowed encodings are ASCII, ISO 8859-15 and UTF-8 (A47 A-1, XII). rÃ©glÃ©e is "réglée" encoded twice: someone opened a UTF-8 file as Latin-1 and saved it as UTF-8 again. The labels are now wrong in the copy the auditor reads.

Fix: pick one encoding and never re-save the file in a text editor or spreadsheet. A file in UTF-16 ("Unicode text" in Excel) is outside the list too: re-export it as UTF-8.

Be aware: no automatic check can be sure here. A double-encoded label is still valid UTF-8, so both tools below accept it. Search the file for Ã before sending it.

4. Misspelled or reordered headers

JournalCode|JournalLib|EcritureNum|DateEcriture|CompteNum|CompteLib|CompAuxNum|CompAuxLib|PieceRef|PieceDate|EcritureLib|Credit|Debit|EcritureLet|DateLet|ValidDate|Montantdevise

Why it fails: three problems in one line. DateEcriture instead of EcritureDate, Credit before Debit, and Idevise missing. The checker reports:

error header_count x1: The header must contain exactly 18 columns.
error header_missing x2: Mandatory column missing from the header: EcritureDate.
error header_unknown x1: Header column not defined by article A47 A-1.
error header_order x1: The header columns are not in the required order.

Fix: copy the header from the table above, exactly, case included. Empty optional columns stay in the header.

5. Dates not in AAAAMMJJ

AC|Achats|000009|20250230|613200|Locations immobilieres|||FL02|20250205|Facture FL02 SCI Les Tilleuls|1200,00|0,00|||20250205||
AC|Achats|000026|12/04/2025|626000|Frais postaux et telecom|||FT04|20250411|Facture FT04 Telecom Ouest|89,90|0,00|||20250411||

Why it fails: dates are AAAAMMJJ with no separator (A47 A-1, XII). 12/04/2025 has the wrong format. 20250230 has the right format but does not exist (there is no 30 February), which a format check alone misses:

error date_invalid x3: Non-existent date in EcritureDate. - line(s) 21, 22, 23
error date_format x3: Wrong date format in EcritureDate (expected AAAAMMJJ). - line(s) 64, 65, 66

Fix: set the export's date format in the software. A non-existent date usually comes from a manual entry: correct the entry, then export again.

6. Decimal point or thousands separators in amounts

VE|Ventes|000002|20250310|411000|Clients|||F000002|20250310|Facture F1|120.00|0,00|||20250310||
VE|Ventes|000002|20250310|411000|Clients|||F000002|20250310|Facture F1|1 200,00|0,00|||20250310||

Why it fails: the comma separates units from decimals, and no thousands separator is accepted (A47 A-1, XII). 120.00 and 1 200,00 both fail.

Fix: 120,00 and 1200,00. One detail people get wrong in the other direction: a negative amount may carry its sign as the first character on the left or the last on the right (-150,00 or 150,00-), both are legal.

7. Unbalanced entries

VE|Ventes|000039|20250610|411000|Clients|CLI001|Atelier Durand|F2025-06|20250610|Facture F2025-06 Atelier Durand|3960,00|0,00|||20250610||
VE|Ventes|000039|20250610|706000|Prestations de services|||F2025-06|20250610|Facture F2025-06 Atelier Durand|0,00|3200,00|||20250610||
VE|Ventes|000039|20250610|445710|TVA collectee|||F2025-06|20250610|Facture F2025-06 Atelier Durand|0,00|660,00|||20250610||

Why it fails: double-entry bookkeeping. The lines of one entry (same EcritureNum) must have total debit = total credit, and so must the whole file. Here 3960,00 debit against 3860,00 credit:

error entry_unbalanced x1: Unbalanced entry: debit - credit difference of 100,00.
error file_unbalanced x1: The file is unbalanced: total debit 193104,48, total credit 193004,48, difference 100,00.

Fix: software does not book unbalanced entries, so this almost always means the export lost or changed lines: a filter on accounts, a truncated label that shifted a column, or a manual edit. Find the entry by its number and compare with the ledger.

8. Gaps or duplicates in EcritureNum

AC|Achats|000046|20250704|401000|Fournisseurs|FOU002|SCI Les Tilleuls|FL07|20250704|Facture FL07 SCI Les Tilleuls|0,00|1440,00|||20250704||
VE|Ventes|000050|20250710|411000|Clients|CLI002|Boulangerie Martin|F2025-07|20250710|Facture F2025-07 Boulangerie Martin|4140,00|0,00|||20250710||

Why it fails: EcritureNum is "the number on a continuous sequence" (A47 A-1, VII). Entries 47 to 49 are missing, which is exactly what an auditor looks for: deleted entries.

error num_gap x1: Numbering gap: 3 number(s) missing, from 47 to 49.

The sequence can be global or per journal (VE0001, AC0001…); a checker has to work out which one the file uses before counting gaps. The same number used twice for two different entries is the opposite error.

Fix: if entries were really deleted, the file shows it and you need an explanation. More often, the export left out a journal or a period: export the whole fiscal year, all journals.

9. Missing ValidDate or validation out of order

VE|Ventes|000002|20250310|411000|Clients|||F000002|20250310|Facture F1|120,00|0,00|||||

Why it fails: ValidDate is the date the entry became final and can no longer be changed. The file is sorted in chronological order of validation (A47 A-1, VII), so an empty ValidDate means a draft entry was exported. Dates going backwards against the numbering are a red flag too:

error validdate_not_chronological x1: Validation date earlier than that of entry no. 71 (20251020): validation must follow numbering order.

Fix: validate (close) the draft entries for the year in the software, then export again.

10. Opening entries missing or misplaced

VE|Ventes|000001|20250310|411000|Clients|||F000001|20250310|Facture F1|120,00|0,00|||20250310||
VE|Ventes|000001|20250310|706000|Prestations|||F000001|20250310|Facture F1|0,00|120,00|||20250310||
AN|A-nouveaux|000002|20250101|512000|Banque|||AN2025|20250101|Reprise des soldes|15000,00|0,00|||20250315||
AN|A-nouveaux|000002|20250101|101000|Capital|||AN2025|20250101|Reprise des soldes|0,00|15000,00|||20250315||

Why it fails: the file must include the entries that record the opening balance sheet (à-nouveaux), and they normally take the first entry numbers of the year (A47 A-1, VII). The administration accepts them later in the file only if they cannot come first and the auditor can still identify them (BOI-CF-IOR-60-40-20). A file with no opening entries at all does not let the auditor check the balances.

Fix: include the opening journal (usually AN) in the export and number it first. Be aware: I know of no automatic checker, including mine, that verifies this today; check it by eye in the first lines of the file.

A 20-line header check in Python

The header causes a large share of rejections and is the easiest thing to check. This is the header logic of fec-lint, reduced to plain Python with no dependency:

EXPECTED = ['JournalCode', 'JournalLib', 'EcritureNum', 'EcritureDate', 'CompteNum', 'CompteLib',
            'CompAuxNum', 'CompAuxLib', 'PieceRef', 'PieceDate', 'EcritureLib', 'Debit', 'Credit',
            'EcritureLet', 'DateLet', 'ValidDate', 'Montantdevise', 'Idevise']


def check_header(path, encoding='utf-8'):
    with open(path, encoding=encoding) as f:
        header = f.readline().lstrip('').rstrip('\r\n')
    sep = '\t' if '\t' in header else '|' if '|' in header else None
    if sep is None:
        return ['no tab or pipe separator in the header']
    names = [n.strip() for n in header.split(sep)]
    errors = []
    if len(names) != 18:
        errors.append(f'{len(names)} columns instead of 18')
    errors += [f'missing column: {n}' for n in EXPECTED if n not in names]
    errors += [f'unknown column: {n}' for n in names if n not in EXPECTED]
    found = [n for n in names if n in EXPECTED]
    if found != [n for n in EXPECTED if n in found]:
        errors.append('columns are not in the required order')
    return errors

On the header from error 4 it returns:

17 columns instead of 18
missing column: EcritureDate
missing column: Idevise
unknown column: DateEcriture
columns are not in the required order

Two details matter. The order check compares only the columns that were found, so a missing column does not hide a swap. And lstrip('') removes the byte-order mark some Windows tools add, which would otherwise make the first column JournalCode.

How to check your own file

Test Compta Demat, the administration's free tool, checks the file the way the DGFiP reads it. Start there; it is the reference.
fec-lint, free and open source (MIT): errors 1, 2, 4, 5 and 6, a UTF-16 file for error 3 and an empty ValidDate for error 9, as a command line tool and an MCP server for AI assistants. It runs on your machine and the file never leaves it.

  pipx install fec-lint
  fec-lint 123456782FEC20251231.txt

FEC Checker, the full pre-audit: everything above plus balance, numbering, validation order, risk signals (weekend postings, round amounts, Benford's law, cash and suspense accounts) and an optional AI-written fix list, in French or English: FEC Checker on Apify.

None of these replaces reading the first and last lines of the file yourself, especially for errors 3 and 10.

Technical guide, not tax advice. It describes the published file format; it does not tell you how the administration will judge your accounts. For that, ask your accountant (expert-comptable).

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