EN 16931: The European Standard for E-Invoices
EN 16931 is the foundation on which all German and European e-invoice formats are built. Understand it, and you understand the entire system.
What the standard defines
EN 16931 defines the semantic data model for the core elements of an electronic invoice. In other words, it specifies which information appears in an invoice and what it means — invoice number, supplier, buyer, line items, tax amounts and so on. It was developed on the basis of the EU directive 2014/55/EU and is maintained by the technical committee CEN/TC 434.
Business Terms and Business Groups
Each individual data field is a Business Term (BT) — for example “invoice date” or “net amount”. Related fields are combined into Business Groups (BG), such as all the details about the seller. This semantic layer is independent of the technical representation.
Two syntaxes: UBL and CII
To make the model machine-readable, the standard prescribes two XML syntaxes:
- UBL 2.1 (OASIS) — used by Peppol BIS and optionally in XRechnung.
- UN/CEFACT CII — used by ZUGFeRD/Factur-X and optionally in XRechnung.
Both represent the same data model, just with different element names. Read more under UBL vs. CII.
CIUS and extensions
The standard is deliberately kept general. For specific use cases it is adapted:
- CIUS (Core Invoice Usage Specification): narrows the standard (makes optional fields mandatory, forbids others) — but remains fully conformant. Examples: XRechnung and Peppol BIS.
- Extension: adds data beyond the core model and is itself no longer a conformant implementation.
Why this matters for you
Because XRechnung, ZUGFeRD and Peppol all build on EN 16931, they are interoperable at their core. Validating “against EN 16931” means the invoice correctly fulfils the common data model — the basic prerequisite for any recipient being able to process it.
Check it yourself
You can have any e-invoice validated against EN 16931 — the validation runs locally in the browser, without your data ever leaving your computer.
Frequently asked questions
What is EN 16931?
EN 16931 is the European standard that defines the semantic data model for the core elements of an electronic invoice. It is the common foundation of XRechnung, ZUGFeRD and Peppol BIS.
Which syntaxes does EN 16931 allow?
Two XML syntaxes: UBL 2.1 (OASIS) and UN/CEFACT CII. Both represent the same data model, just with different element names.
What does CIUS mean?
A Core Invoice Usage Specification narrows the standard for a specific context while remaining conformant. XRechnung and Peppol BIS are CIUS of EN 16931.