What is UBL?
UBL (Universal Business Language) is an OASIS open standard defining XML schemas for structured business documents including invoices, orders, credit notes, and despatch advices. UBL 2.1 is the basis for Peppol BIS Billing 3.0 and EU public procurement e-invoicing mandates. It provides a vendor-neutral, royalty-free framework for cross-system document exchange.
Which version of UBL should be used?
UBL 2.1 is the version mandated for Peppol BIS Billing 3.0 and EU public procurement. UBL 2.3 is the current release but has limited adoption. UBL 2.0 is deprecated. Implementations targeting Peppol or EU compliance should use UBL 2.1.
What is the difference between UBL and CII?
UBL and CII are both XML invoice formats accepted by EN 16931 as alternative syntaxes, but they differ in schema design and network adoption.
- UBL: Developed by OASIS. Mandated by Peppol. Used in EU, Australia, Singapore, New Zealand.
- CII: Developed by UN/CEFACT. Used in Factur-X, ZUGFeRD. Preferred in France and Germany.
- EN 16931: The European semantic standard supports both UBL and CII as syntax bindings.
What is a CIUS?
A CIUS (Core Invoice Usage Specification) is a national or sector-specific constraint applied to a base UBL or CII specification. Peppol BIS Billing 3.0 is a CIUS of EN 16931. CIUS rules can make optional fields mandatory, restrict allowed values, or add business rules on top of the base standard.
Frequently Asked Questions
- Is UBL mandatory for e-invoicing?
- UBL is mandatory for Peppol-based e-invoicing in over 40 countries and for EU public procurement under Directive 2014/55/EU. For private B2B in France, UBL is one of several accepted formats alongside Factur-X and CII.
- How many document types does UBL support?
- UBL 2.1 defines 65 document schemas including Invoice, Credit Note, Order, Order Response, Despatch Advice, Receipt Advice, Catalogue, and Application Response. Most e-invoicing implementations use a subset of four to eight document types.
- What is Peppol BIS Billing 3.0?
- Peppol BIS Billing 3.0 is the implementation specification for invoices and credit notes on the Peppol network. It is a CIUS (constrained implementation) of UBL 2.1 conforming to EN 16931. It defines mandatory fields, allowed code lists, and business rules beyond the base UBL schema.
- Can UBL invoices include PDF attachments?
- Yes. UBL supports embedded binary attachments within the document structure. A PDF version of the invoice can be embedded as a base64-encoded attachment, providing a human-readable representation alongside the machine-readable XML.