Rule at a Glance
| ID | Severity | Context (XPath) |
|---|---|---|
| BR-02 | Fatal (error) | ubl:Invoice |
| Series reference: BR-02 | Schematron ID: ibr-002 | ||
Classification
Transaction Data — The invoice number is a transaction-level identifier generated by the seller's system for each unique invoice document.
What the Rule Is Checking
BR-02 requires that every invoice contains a non-empty cbc:ID element at the invoice header level. This is BT-1 in the PINT-AE data model — the Invoice number. The rule fails fatally if the element is absent or contains only whitespace. There is no prescribed format for the number: it must simply be present and non-empty.
BT-1 is the human-readable reference that the seller assigns to uniquely identify the invoice within their own numbering system. It appears on printed or PDF representations of the invoice and is the reference buyers use in payment remittances and dispute correspondence.
Why This Rule Exists
The UAE VAT Decree-Law and its executive regulations require that every tax invoice carries a unique sequential number. Under MD No. 243 of 2025, the 51 mandatory PINT-AE data fields include the invoice number as a core field. Without BT-1, an invoice cannot be matched, audited, or cross-referenced against payments or credit notes by either trading party or by the FTA.
In the Peppol 5-Corner model, BT-1 is also used by the buyer's system to detect duplicate invoice submissions. If the same BT-1 appears twice from the same seller (BT-27 and BT-29), the receiving system should reject the second document as a potential duplicate — a protection that depends entirely on BT-1 being consistently populated.
Standard / Code List
There is no code list for BT-1 — it is a free-text string of maximum 200 characters. However, the UAE e-invoicing system imposes a practical constraint: invoice numbers must be unique within the seller's business for audit traceability. Sequential numbering (e.g., INV-2027-00001) or a structured alphanumeric scheme is best practice. Gaps in the sequence must be explainable.
UAE Data Example
PASSES ✓
<cbc:ID>INV-2027-00842</cbc:ID>
PASSES ✓ — alphanumeric reference
<cbc:ID>AE-TAX-INV/FY27/Q1/0056</cbc:ID>
FAILS ✗ — Element absent:
<!-- No cbc:ID present at invoice header -->
FAILS ✗ — Empty element:
<cbc:ID></cbc:ID>What Your ERP / IT Team Must Ensure
- The invoice numbering sequence must be maintained consistently in the ERP and must carry through to the UBL output without transformation or truncation.
- ERP configurations that use document type prefixes (e.g., SAP SD billing document numbers or Oracle AR transaction numbers) must map the full document reference — not just a numeric portion — to BT-1.
- Where invoices are generated by subsidiary systems (e.g., a contract billing engine, a field service system) and then passed to ERP, the source invoice number must be preserved as BT-1 — not replaced with an ERP-generated sequence number that the buyer will not recognise.
- Duplicate detection should be implemented before ASP submission: if BT-1 already exists in the sent-invoice log for the same seller TIN (BT-29), the document should be flagged for review before transmission.
Related Rules
BR-01 (Specification identifier), BR-03 (Invoice issue date), BR-10 (Buyer reference or contract reference), 51 Mandatory PINT-AE Fields