What it means
The tender or lot reference (BT-17) links the invoice to the tender or lot it relates to. In UBL it is the cbc:ID inside cac:OriginatorDocumentReference. The check counts these identifiers and allows at most one.
Why it matters
EN 16931 has one field for this reference per invoice. A second reference would leave the recipient guessing which tender the invoice belongs to, so the file is rejected.
How to fix it
In your invoicing software, check the tender, lot or project reference fields and leave one. If several apply, choose the one the buyer asks for and mention the others in the invoice note. If you build the XML yourself, keep one cbc:ID in cac:OriginatorDocumentReference.
The rule as published
An Invoice shall contain maximum one Originator document reference identifier (BT-17). Business terms: BT-17
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-SR-56 still fails, and which other rules do.
Related rules
- BR-DE-CVD-02 Clean vehicle (CVD) invoices need a tender or lot reference
- BR-RO-L0307 Tender or lot reference: 200 characters at most
- UBL-SR-57 Each party can have only one legal registration block
- UBL-SR-58 A bank branch must have exactly one bank identifier
- UBL-SR-59 A bank account must have exactly one account identifier
- UBL-SR-55 An invoice can have only one direct debit mandate