Peppol-check

Duplicate invoices via Peppol and email: find them before the VAT return

Many suppliers send the same invoice twice: once through Peppol and once as a PDF by email. That is allowed, but since 1 January 2026 the invoice sent through Peppol is the only legal invoice2. A PDF by email is not e-invoicing in the strict sense1. If the PDF is booked as well, the purchase is in the journal twice and the VAT is deducted twice.

Where duplicates come from

  • Peppol plus PDF. The supplier's software attaches a PDF automatically, or the client forwards the PDF to the firm again.
  • Foreign suppliers. They do not have to send through Peppol and often keep emailing PDFs3. When such a supplier later moves to Peppol, the same invoice sometimes arrives both ways.
  • A client on 0208 and 9925. A company registered under both numbers without knowing it can receive invoices twice3. See 0208 or 9925.
  • Credit notes. These go through Peppol too4. If a credit note does not arrive, the invoice it cancels simply stays in the journal.

How to find them

  1. Export the purchase journal for the period as CSV, with supplier, invoice number, date and amount. Or collect the UBL files (XML) that came in through Peppol.
  2. Look for the same invoice number per supplier. Two lines with the same number from the same supplier are almost always a duplicate.
  3. Look for the same amount per supplier within a few days. A PDF sometimes gets a different number or a typo when it is booked. The same amount in the same week is worth a look, though it can also be a recurring invoice.
  4. Count credit notes as negative. Then an invoice and its credit note show as a pair, not as two purchases.
  5. Book only the Peppol version and ask suppliers who also email to stop once your client receives through Peppol.

In Peppol-check you drop UBL invoices or a CSV export of the purchase journal on a client's page. You get back the lines with the same invoice number, and those with the same amount from the same supplier within 7 days. The files themselves are not kept, only the result. Does your accounting software already do this when booking? Then you may not need this.

Sources

  1. FPS BOSA, "Hoe werkt e-facturatie?" (in Dutch): a PDF by email is not e-invoicing in the strict sense, read on 27 October 2026.
  2. Billit, "Kan je een factuur zowel via e-mail als via Peppol naar een klant sturen?" (in Dutch), read on 27 October 2026.
  3. Peppol Box, "Facturation Peppol Belgique : les vrais problèmes et solutions 2026" (in French): foreign suppliers and double registration, read on 27 October 2026.
  4. FPS BOSA, e-invoicing FAQ (in Dutch), question 5: credit notes also go through Peppol, read on 27 October 2026.

Read also

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