What it means
When an invoice line gives a price base quantity (BT-149), the number of units the price applies to, it must be a positive number above zero, for example 1 or 100.
Why it matters
Peppol BIS Billing 3.0 adds this rule to EN 16931 so that every access point and receiver can process the invoice the same way. The sending or receiving access point rejects an invoice that fails it, so it never reaches the buyer.
How to fix it
Enter the number of units the price is for, usually 1, or leave the base quantity out so it counts as 1. A negative quantity for a return belongs in the invoiced quantity, not in the base quantity. In UBL it is cac:Price/cbc:BaseQuantity.
The rule as published
Base quantity MUST be a positive number above zero. Where this rule applies
| Rule set | Version |
|---|---|
| XRechnung 3.0 (UBL) | 3.0.2 |
| XRechnung 3.0 (UBL credit note) | 3.0.2 |
| XRechnung 3.0 (CII) | 3.0.2 |
| Peppol BIS Billing 3.0 (invoice) | 2026.5 |
| Peppol BIS Billing 3.0 (credit note) | 2026.5 |
Check your file
Drop your e-invoice to see whether PEPPOL-EN16931-R121 still fails, and which other rules do.
Related rules
- PEPPOL-EN16931-R130 The price base quantity must use the same unit as the quantity
- PEPPOL-EN16931-R120 The line amount should equal quantity times price, plus charges, minus discounts
- PEPPOL-EN16931-R111 A line period must end within the invoicing period
- PEPPOL-EN16931-R110 A line period must start within the invoicing period
- PEPPOL-EN16931-R101 Line document references may only be invoiced objects
- PEPPOL-EN16931-R100 At most one invoiced object per line