What it means
The buyer's company registration number (BT-47) identifies the buyer's legal entity in a business register, such as a KvK, SIRET or Companies House number. In UBL it is cbc:CompanyID inside the buyer's cac:PartyLegalEntity. The rule counts those elements and allows one.
Why it matters
EN 16931 allows at most one buyer company registration number per invoice or credit note.
How to fix it
Open the customer record in your invoicing software and look for fields such as company number, chamber of commerce number or registration number. Make sure only one of them is filled in and exported as the buyer's registration number, and that the VAT number is not repeated there. In the XML, keep one cbc:CompanyID in cac:AccountingCustomerParty/cac:Party/cac:PartyLegalEntity.
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
Buyer legal registration identifier shall occur maximum once 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-17 still fails, and which other rules do.
Related rules
- UBL-SR-18 An invoice can have only one buyer VAT number
- UBL-SR-19 The payee needs one name, different from the seller's
- UBL-SR-20 The payee can have one identifier and must differ from the seller
- UBL-SR-21 A separate payee needs a different name and at most one registration number
- UBL-SR-22 A tax representative can have only one name
- UBL-SR-23 A tax representative can have only one VAT number