REF: References incorrect
What it means
Peppol reason REF in an Invoice Response means the invoice does not contain the references the buyer needs to route it for approval or processing.
The usual cause
A reference the buyer requires is missing or wrong, for example the purchase order number (BT-13) or the buyer reference (BT-10). The response may name the field and the correct value.
How to fix it
Ask the buyer which reference they need, or use the one the response gives. Send the reference separately, or send a corrected invoice if the response asks you to reissue it.
Once the file is corrected, check it again for free: Validate a Peppol BIS invoice
Or fix the invoice in a form and download the corrected file, for 1 credit: Fix a rejected e-invoice
The code as published
Read the official document . Source: Peppol BIS Invoice Response 3.1 (BIS 63A), with its code lists, version Peppol BIS 3, 2026-Q2 release, published by OpenPeppol AISBL, read on 8 November 2026.
Klarbon explains each code in its own words; the official wording is in the document linked above.
Look at your file
Check the invoice against the rules this portal applies: Validate a Peppol BIS invoice. Validate a Peppol BIS invoice