What it means
The seller's details (cac:AccountingSupplierParty/cac:Party) may hold at most two cac:PartyTaxScheme blocks. EN 16931 has room for two seller tax identifiers: the VAT number (BT-31) and the tax number (BT-32), such as the German Steuernummer. Each one sits in its own block. This rule counts the blocks, not the types or values of the identifiers.
Why it matters
EN 16931 allows at most two tax scheme blocks in the seller's details.
How to fix it
Open the seller details in your invoicing software and look for duplicated tax or VAT entries, for example the same VAT number entered twice or in two fields. Remove duplicate or unnecessary tax scheme entries so that at most two remain, then export again. If you build the XML yourself, remove the extra cac:PartyTaxScheme elements under cac:AccountingSupplierParty/cac:Party.
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
Party tax scheme shall occur maximum twice in accounting supplier party 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-42 still fails, and which other rules do.
Related rules
- UBL-SR-43 Only the invoiced object reference may carry a scheme identifier
- UBL-SR-44 An invoice can have only one payment reference
- UBL-SR-45 Only one due date in the payment means
- UBL-SR-46 The payment means text can only be given once
- UBL-SR-47 All payment means codes on an invoice must be the same
- UBL-SR-48 Every line must have exactly one VAT category