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Warning

UBL-CR-126: Leave the format code out of an attachment link

In short

Warning: worth checking.

UBL-CR-126 means a document link in your UBL invoice or credit note has a format code (FormatCode), which EN 16931 does not use. Remove that element from the link.

On this page

What it means

This rule checks that cbc:FormatCode is absent from document-level cac:AdditionalDocumentReference/cac:Attachment/cac:ExternalReference in a UBL invoice or credit note. It applies to every additional document reference. For a linked supporting document (BG-24), the web address is BT-124.

Why it matters

EN 16931 does not use a separate format code in this document-link element.

How to fix it

Remove cbc:FormatCode from cac:AdditionalDocumentReference/cac:Attachment/cac:ExternalReference. If your invoicing software adds it, ask your software supplier to leave it out. Export the corrected file and check it again.

Once the file is corrected, check it again for free: Validate an invoice against EN 16931

Or fix the invoice in a form and download the corrected file, for 1 credit: Fix a rejected e-invoice

The rule as published

A UBL invoice should not include the AdditionalDocumentReference Attachment External FormatCode

Where this rule applies

Rule set Version
EN 16931 (UBL) 1.3.17
EN 16931 (UBL credit note) 1.3.17
XRechnung 3.0 (UBL) 3.0.2
XRechnung 3.0 (UBL credit note) 3.0.2
Peppol BIS Billing 3.0 (invoice) 2026.5
Peppol BIS Billing 3.0 (credit note) 2026.5
SI-UBL 2.0 / NLCIUS (invoice) 2.0.3.13
SI-UBL 2.0 / NLCIUS (credit note) 2.0.3.13
France CTC (UBL invoice) 1.4.0-04
France CTC (UBL credit note) 1.4.0-04
CIUS-RO UBL Invoice 1.0.9 1.0.9
CIUS-RO UBL Credit Note 1.0.9 1.0.9
Rule text from phive-rules 4.6.4.

Check your file

Drop your e-invoice to see whether UBL-CR-126 still fails, and which other rules do.

Updated 6 November 2026