What it means
This rule checks that no VAT breakdown row (cac:TaxSubtotal under a document-level cac:TaxTotal, BG-23) has a cbc:BaseUnitMeasure. In UBL this element records the quantity on which a per-unit tax is based, rather than just naming a unit of measure. EN 16931 uses a taxable amount (BT-116) for each VAT breakdown row, not this per-unit tax field. The check applies to invoices and credit notes.
Why it matters
EN 16931 does not use this tax-base measure in the VAT breakdown, which records taxable amounts and VAT amounts.
How to fix it
Delete cbc:BaseUnitMeasure from each cac:TaxSubtotal inside a cac:TaxTotal directly under Invoice or CreditNote. If you need to include a tax or duty other than VAT, check how it should be represented rather than using this field. If your invoicing software adds the element, ask its supplier to remove it from the export. 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 TaxTotal TaxSubtotal BaseUnitMeasure 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-500 still fails, and which other rules do.
Related rules
- UBL-CR-501 Leave the per-unit tax amount out of the VAT breakdown
- UBL-CR-502 Leave the tax tier range out of the VAT breakdown
- UBL-CR-503 The VAT subtotal should not have a tier rate
- UBL-CR-504 The VAT category should not have a name
- UBL-CR-505 The VAT category should not have a base unit of measure
- UBL-CR-506 The VAT category should not have a per-unit amount