Anyone getting started with e-invoicing soon comes across a series of abbreviations: UBL, CII, Peppol BIS, Factur-X, ZUGFeRD and XRechnung. They look like competing standards, but in reality they largely build on the same foundation. On this page, you can read what each format is, how the formats relate to one another and which format is relevant in which situation.
Why are there multiple e-invoice formats?
The basis of e-invoicing in Europe is the European standard EN 16931. This standard is not a file format. It is a semantic data model: EN 16931 describes which data an e-invoice must or may contain and what that data means, such as the identification of supplier and buyer, invoice lines, VAT amounts and payment details.
To turn that data model into an actual file, a syntax is needed: a concrete XML format in which the data is recorded. Two syntaxes have been designated for EN 16931: UBL (Universal Business Language), developed within OASIS, and UN/CEFACT CII (Cross Industry Invoice).
On top of this, countries and networks have drawn up their own specifications for their own needs. Such a specification is called a CIUS (Core Invoice Usage Specification). A CIUS tightens the European standard with additional rules, for example for invoicing public sector bodies or for a specific network.
This explains why UBL, CII, Peppol BIS, Factur-X and XRechnung exist side by side. The underlying data is largely the same, because they all go back to EN 16931. The difference lies in the chosen syntax, the additional rules and the application. You can read more background on the standard itself in What is the EN 16931?
The formats at a glance
| Format | What it is | Syntax | Where it is used |
|---|---|---|---|
| UBL | XML standard from OASIS; one of the two EN 16931 syntaxes | XML | International; basis for Peppol BIS and NLCIUS |
| UN/CEFACT CII | Invoice format from UN/CEFACT; second EN 16931 syntax | XML | Basis for Factur-X/ZUGFeRD; also used on its own |
| Peppol BIS Billing 3.0 | CIUS of EN 16931 for the Peppol network | XML (UBL) | Peppol network; standard in Belgium and Luxembourg |
| NLCIUS | Dutch CIUS of EN 16931 | XML (UBL) | The Netherlands, including invoicing to public sector bodies |
| Factur-X / ZUGFeRD | Hybrid: PDF with embedded XML; technically the same standard, with a French and a German name | PDF + XML (CII) | France and Germany; note: the MINIMUM and BASIC-WL profiles do not qualify as e-invoices in Germany |
| XRechnung | German CIUS of EN 16931 | XML (UBL or CII) | German public sector, and also between businesses in Germany |
How do you choose the right format?
Which format you need depends on the channel through which you invoice and on your customer’s requirements. If you invoice via Peppol, Peppol BIS Billing 3.0 is the implementation to use; you can read how the network works in What is Peppol? If you invoice a French or German customer who asks for a hybrid format, Factur-X or ZUGFeRD may be relevant. If you invoice German public authorities, XRechnung is often required.
By country: in the Netherlands the NLCIUS (the Dutch CIUS) or Peppol BIS, in Belgium and Luxembourg Peppol BIS Billing 3.0, in Germany XRechnung or ZUGFeRD (and EDI under certain conditions), and in France the base formats UBL, CII and Factur-X.
Existing EDI formats such as EDIFACT may remain in use in some countries, provided all mandatory data can be extracted from them; in Germany, EDI that does not meet this requirement is still permitted until the end of 2027.
In practice, as a sender you rarely need to choose a format yourself. Your accounting or invoicing software, or your service provider, determines and generates the correct format based on the channel through which you send.
What this means for software vendors
For software vendors, format support is a core part of e-invoicing functionality. Go through the following points.
Format support checklist
- Does your software support generating and validating EN 16931-compliant XML in both UBL and CII syntax, or at least the syntax required by your main target market?
- Can your software generate Peppol BIS Billing 3.0 if you send via Peppol?
- Do you have a strategy for hybrid formats (Factur-X/ZUGFeRD) if your customers are active in France or Germany?
- Do you validate outgoing invoices against the correct CIUS rules before sending, to prevent rejections?
For businesses
You do not need to manage invoice formats yourself. It is, however, wise to know which format your software uses and why it suits your customers, so that you can ask targeted questions if a customer requires a specific format or rejects an invoice.
For integrators
The key is correct format detection and conversion between systems. An invoice may arrive as UBL, CII or a hybrid PDF and may need to be passed on in a different format. Because all formats go back to EN 16931, conversion is perfectly feasible in terms of content, provided you take into account the additional rules of the relevant CIUS.
Further reading
What is the EN 16931?: the European standard behind all formats. What is Peppol?: the network for which Peppol BIS Billing 3.0 was developed. Prefer not to maintain formats yourself? In the comparison tool you will find providers that handle validation and conversion for you.
