Check invoice numbers before you send — duplicates get rejected, and the invoice must still be legally correct

Guidance published ahead of the 1 September 2026 go-live stresses two practical points. First, validate invoice numbers upstream, in your own system, before sending: once invoices flow through approved platforms, a repeated invoice number is a common cause of outright rejection. This especially catches businesses where two people, or two systems such as a till and an accounting package, both issue invoices and the numbering overlaps. Second, the invoice must remain legally correct in its own right even when your platform routes it using a technical identifier — a routing code is not a substitute for the details the law requires on the invoice itself. UPDATE (26 September 2026): the first numbers from the September go-live are out and they make the same point in figures. By 14 September about 4.81 million entities had designated an approved platform, but 14.4 percent of the invoice flows reported to the DGFiP were non-compliant, and on 10 September alone the rejection rate reportedly reached 43.5 percent. A second industry tracker independently put the market-wide rejection rate in the first weeks at roughly 20 percent, so the pattern is corroborated even though the exact figures come from one source. Appointing a platform is not the same as being compliant. What gets invoices rejected is wrong or missing data: stale customer records, an invalid SIREN or SIRET, missing mandatory fields, wrong VAT treatment, or a chain that was never tested end to end from your software to your customer's platform. Do one live test with a real customer before you rely on the system. The DGFiP refreshed its official list of approved platforms on 22 September 2026, so if you are still choosing, read the live list on impots.gouv.fr rather than a copy on a vendor site.

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