Invoice numbering rules
for auto-entrepreneurs

Invoice numbering may seem like a minor detail, but in France it is governed by law and scrutinised during tax audits. Getting it wrong can raise red flags with the tax authorities and lead to penalties. This article explains the legal rules, shows you accepted numbering formats with concrete examples, and highlights the mistakes you must avoid as an auto-entrepreneur in 2026.

The legal principle: continuous chronological sequence

French law requires that every invoice bear a unique number assigned according to a continuous chronological sequence. This principle is established by Article L441-3 of the French Commercial Code (Code de commerce) and Article 242 nonies A of Annex II to the General Tax Code (CGI). The key requirements are:

• Uniqueness: no two invoices may share the same number. Each number must be assigned once and only once.
• Chronological order: invoice numbers must follow a strictly chronological progression. Invoice number 15 must have been issued after invoice number 14 and before invoice number 16.
• Continuity: there must be no gaps in the sequence. Jumping from invoice 12 to invoice 14 without a number 13 constitutes an anomaly.

The purpose of these rules is to prevent fraud. A continuous, unbroken numbering sequence makes it very difficult to delete or hide invoices -- which is precisely what the tax authorities want to ensure. During a tax audit (controle fiscal), the auditor will systematically check that your numbering is sequential and complete.

Accepted numbering formats

French law does not prescribe a specific numbering format. You have flexibility in choosing the structure of your invoice numbers, as long as the sequence is chronological and uninterrupted. Here are the most commonly used formats:

Simple sequential numbering

The simplest approach: a plain sequential number that increments with each invoice.

• 001, 002, 003, ...

This works but can become ambiguous over multiple years, since the same numbers would repeat each year if you restart the sequence.

Year-based numbering

The most popular format among auto-entrepreneurs. It incorporates the year, making each number inherently unique across years.

• 2026-001, 2026-002, 2026-003, ...
• 2026001, 2026002, 2026003, ...

Prefixed numbering

Adding a prefix (typically "FA" for facture) provides additional clarity and distinguishes invoices from other document types (quotes, credit notes, etc.).

• FA-2026-0001, FA-2026-0002, FA-2026-0003, ...
• F2026-001, F2026-002, F2026-003, ...

Year-month numbering

Some auto-entrepreneurs include the month for even more granularity. This can be useful if you issue many invoices per month.

• FA-202603-001, FA-202603-002, ...
• 2026-03-001, 2026-03-002, ...

With month-based formats, the counter typically restarts each month, which is acceptable as long as the overall sequence remains chronological and each number is unique.

Restarting the sequence each year

You are allowed to restart your invoice numbering at the beginning of each calendar year. This is the most common practice among auto-entrepreneurs and small businesses in France. When you do so, the year must be embedded in the number format to avoid ambiguity. For example:

• Last invoice of 2025: FA-2025-0087
• First invoice of 2026: FA-2026-0001

This is perfectly legal and causes no issues during a tax audit, because the year prefix makes every number globally unique. What you must never do is restart the sequence mid-year without changing the format, as this would create duplicates.

Credit notes and separate numbering

Credit notes (factures d'avoir) must follow their own separate numbering sequence. This is important: a credit note is not a negative invoice -- it is a distinct document type with its own numbering rules. Common conventions include:

• AV-2026-001, AV-2026-002, ... (AV for avoir)
• CN-2026-001, CN-2026-002, ... (CN for credit note)

Each credit note must reference the original invoice it relates to, including the invoice number and date. The credit note sequence must also be continuous and chronological, just like the main invoice sequence.

What to do if you need to cancel an invoice

A critical rule: never delete an invoice number from your sequence. If you have issued an invoice in error, you must not simply remove it and pretend it never existed. The correct procedure is:

1. Issue a credit note (avoir) that references the erroneous invoice.
2. The credit note cancels the original invoice in full or in part.
3. If needed, issue a new corrected invoice with the next number in your sequence.

This preserves the integrity of your numbering chain. The original invoice number remains in the sequence, the credit note explains why it was cancelled, and the replacement invoice continues the normal progression. During an audit, the auditor can see a clear, documented trail of what happened.

Common numbering mistakes to avoid

Here are the most frequent errors we see among auto-entrepreneurs, and each one can cause problems during a tax audit:

• Gaps in the sequence: jumping from invoice 12 to invoice 14. Even if invoice 13 was simply a draft you decided not to send, the gap looks suspicious. Issue a credit note instead of deleting.
• Duplicates: issuing two invoices with the same number, even to different clients. Every number must be unique across your entire invoicing history.
• Non-chronological order: issuing invoice 2026-045 on 15 March and invoice 2026-044 on 20 March. Numbers must always progress forward in time.
• Changing format mid-year: switching from "2026-XXX" to "FA-2026-XXXX" halfway through the year creates confusion and potential duplicates. Choose a format at the start of the year and stick with it.
• Using random or arbitrary numbers: invoice numbers like "INV-A7B3" or "20260315-CLIENT" are not based on a chronological sequence and will be flagged as non-compliant.
• Not numbering credit notes separately: credit notes must have their own distinct sequence. Mixing them into your main invoice numbering creates irregularities.

Tools to automate numbering

The simplest way to avoid numbering errors is to use invoicing software that handles it automatically. Tools like Dokta assign sequential numbers to each invoice you create, prevent duplicates, and maintain the chronological chain without any manual effort on your part. This eliminates the most common source of compliance errors and saves you time on every invoice.

Frequently asked questions

Can I restart invoice numbering each year?

Yes, provided the year is embedded in the number format. Going from 2025-047 to 2026-001 is perfectly valid because the two series are distinct. However, if you use a format without a year prefix (001, 002...), you cannot restart at 001 in January as it would create duplicates.

What to do if I skipped an invoice number?

You cannot retroactively create an invoice with the missing number. The correct approach is to document the gap in your accounting records with a written note explaining that the number was unused due to a sequencing error. This written trace justifies the anomaly in the event of a tax audit.

Must numbering be continuous across all clients?

Yes. Invoice numbering must follow a single chronological sequence regardless of the client. Invoice 2026-015 for Client A must be followed by 2026-016, even if that invoice is for Client B. Each number identifies a unique transaction in your overall accounting.

Can I use letters in my invoice number?

Yes. French law does not require a purely numeric format. You can use alphabetical prefixes such as FA-2026-001 or DESIGN-2026-001. The key requirement is that the sequence remains chronological, continuous and free of duplicates. Letter prefixes are even recommended to distinguish document types (invoices, credit notes, advance payments).