Invoice numbering: the French rules you must follow (and how to comply on Shopify)

It is one of the first things the French tax administration checks in an audit: invoice numbering. The rules are simple to state, but surprisingly easy to break when you sell online — especially with several stores. Let’s break it down.

What the law says

The French tax code (article 242 nonies A) requires every invoice to carry a unique number, drawn from a chronological and continuous sequence:

• unique: two invoices can never share a number;
• chronological: numbers follow issuance order;
• continuous: no gap in the sequence. A cancelled invoice does not free its number — you issue a credit note, you never delete.

Numbering may include a prefix (year, series…), for example 2026-00042, as long as the sequence stays continuous within the series.

Why it is so easy to get it wrong on Shopify

Shopify numbers orders (#1001, #1002…), not invoices. The two sequences diverge quickly:

• an order cancelled before payment produces no invoice → gap;
• test orders, drafts and exchanges create order numbers with no accounting reality;
• Shopify’s order counter is specific to each store.

Using the order number as your invoice number is therefore risky. You need a dedicated invoicing sequence, incremented only when an invoice is actually issued.

The tricky case: several Shopify stores, one company

Many merchants run several stores (multi-brand, multi-country) under the same legal entity. The continuity rule applies per entity, not per store: if your company sells through three Shopify stores, its invoices must form a single continuous sequence.

Three independent invoicing apps, each with its own counter, produce three parallel sequences — not compliant.

This is exactly why FacturX offers multi-store linking: you link your stores into a single invoicing entity, and every invoice draws its number from the same shared counter, incremented atomically. Store A issues #42, store B issues #43, store A issues #44: continuity guaranteed, hands-free.

Taking over an existing sequence without creating a gap

Migrating from another tool? Your sequence does not restart at 1: it continues. If your last invoice was #1041, the first one issued by the new tool must be #1042.

FacturX handles this scenario with smart sequence initialization: you enter the next number to issue, the app checks that it creates neither a duplicate nor a rollback (it refuses any value below numbers already consumed), and the live preview shows you the next formatted numbers.

Choosing a good numbering format

A readable format makes everyone’s life easier. FacturX lets you compose yours freely with variables:

• FF-{sequence} → FF-1042: the simplest and most robust;
• {YYYY}-{sequence} → 2026-1042: the year as prefix, appreciated by accountants;
• credit notes get their own format (for example CN-{sequence}), as they form a distinct series.

Avoid embedding information that can change (commercial store name, sales channel): an invoice number should stay stable and neutral.

Compliance checklist

1. A sequence dedicated to invoices, not the Shopify order number;
2. Continuous and chronological, including across stores of the same entity;
3. Numbers are reserved at issuance and never reused;
4. Cancellations go through credit notes, never deletions;
5. The issued invoice is immutable and kept for 10 years.

FacturX ticks all five boxes by construction. Install it for free and sleep well before your next audit.