UBL (Universal Business Language) is an open XML standard from OASIS covering invoices, credit notes, orders, despatch advices, and other business documents. UBL 2.1 is the version used in EN 16931 and PEPPOL — if you're sending invoices through the PEPPOL network, the file is almost certainly UBL.
A UBL invoice (Invoice.xml) covers everything: trading parties, line items, tax breakdowns, payment terms. The structure is validated in two passes — first XSD for structure, then Schematron for business rules.
Key facts
- Published by OASIS (open standards consortium)
- Current version: UBL 2.1 (ISO/IEC 19845)
- Used in: PEPPOL BIS Billing 3.0, Nordic e-invoicing, EU public procurement
- Alternative to UN/CEFACT CII for EN 16931 compliance