What it means
The project reference (BT-11) is cbc:ID inside cac:ProjectReference. This rule checks that a document-level cac:ProjectReference in a UBL invoice or credit note does not also contain cac:WorkPhaseReference.
Why it matters
EN 16931 does not use a separate work-phase reference inside the project reference.
How to fix it
Remove cac:ProjectReference/cac:WorkPhaseReference and keep cac:ProjectReference/cbc:ID. If the buyer needs the phase, add it to the project reference text itself if they agree, or mention it in the line description. 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 ProjectReference WorkPhaseReference 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 |
Check your file
Drop your e-invoice to see whether UBL-CR-136 still fails, and which other rules do.
Related rules
- UBL-CR-137 The invoice should not contain a signature block
- UBL-CR-138 Seller details should not carry a buyer-assigned account ID
- UBL-CR-139 Seller details should not carry an additional account ID
- UBL-CR-140 Seller details should not carry a data sending capability
- UBL-CR-141 Seller details should not carry a mark care indicator
- UBL-CR-142 Do not include an attention flag for the seller