What it means
Every invoice line (BG-25) must contain the invoice line identifier (BT-126). It is the number of the line within the invoice, usually 1, 2, 3 and so on.
Why it matters
The buyer's software books and checks every line on its own, often against the purchase order. A line without this detail cannot be matched or posted, so the whole invoice is rejected.
How to fix it
Number every line of the invoice; most invoicing software does this automatically when it exports. If you build the XML yourself, give each line a cbc:ID (UBL) or ram:LineID (CII) that is unique within the invoice.
The rule as published
Each Invoice line (BG-25) shall have an Invoice line identifier (BT-126). Business terms: BG-25, BT-126
Where this rule applies
| Rule set | Version |
|---|---|
| EN 16931 (UBL) | 1.3.17 |
| EN 16931 (UBL credit note) | 1.3.17 |
| EN 16931 (CII) | 1.3.17 |
| 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 |
| Factur-X 1.09 BASIC | 1.0.9-2 |
| Factur-X 1.09 EN 16931 | 1.0.9-2 |
| Factur-X 1.09 EXTENDED | 1.0.9-2 |
| ZUGFeRD 2.5 BASIC | 2.5.2 |
| ZUGFeRD 2.5 EN 16931 | 2.5.2 |
| ZUGFeRD 2.5 EXTENDED | 2.5.2 |
| SI-UBL 2.0 / NLCIUS (invoice) | 2.0.3.13 |
| SI-UBL 2.0 / NLCIUS (credit note) | 2.0.3.13 |
| NLCIUS (CII) | 1.0.3.13 |
| France CTC (UBL invoice) | 1.4.0-04 |
| France CTC (UBL credit note) | 1.4.0-04 |
| France CTC (CII) | 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 BR-21 still fails, and which other rules do.