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Warning

UBL-CR-106: Leave the attachment out of the contract reference

In short

Warning: worth checking.

UBL-CR-106 means the contract reference in your UBL invoice or credit note contains an attachment (cac:Attachment), which EN 16931 does not use there. Remove it from cac:ContractDocumentReference. If you need to include the contract file, use a supporting document reference (BG-24) instead.

On this page

What it means

A UBL invoice or credit note refers to a contract with cac:ContractDocumentReference. EN 16931 only uses the contract number from that block (BT-12, in cbc:ID). This rule checks that the block does not also contain an attachment (cac:Attachment), such as an embedded file or a link to the contract. Attachments belong to supporting documents (BG-24).

Why it matters

EN 16931 keeps attachments separate from the contract reference, which identifies the contract by its number.

How to fix it

To include the contract itself, add it as a supporting document: attach the file in your invoicing software, or in the XML put cac:Attachment inside a cac:AdditionalDocumentReference. Then remove cac:Attachment from cac:ContractDocumentReference and keep cbc:ID with the contract number. Recheck the corrected file.

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 ContractDocumentReference Attachment

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-106 still fails, and which other rules do.

Updated 6 November 2026