Anyone starting with e-invoicing quickly runs into 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 will learn 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, you need a syntax: 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 to meet 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 all of them trace back to EN 16931. The differences lie in the chosen syntax, the additional rules and the use case. For more background on the standard itself, see What is EN 16931.
The formats at a glance
UBL
UN/CEFACT CII
Peppol BIS Billing 3.0
Factur-X / ZUGFeRD
XRechnung
How do you choose the right format?
The format you need depends on the channel you invoice through and on your customer’s requirements. If you invoice via Peppol, Peppol BIS Billing 3.0 is the implementation to use; learn how the network works in What is Peppol. If you invoice a French or German customer that asks for a hybrid format, Factur-X or ZUGFeRD may be relevant. If you invoice German public sector bodies, XRechnung is often required.
In practice, as a sender you rarely have to choose a format yourself. Your accounting or invoicing software, or your Peppol Service Provider, determines and generates the right format based on the channel you send through.
What this means for software vendors
For software vendors, format support is a core part of e-invoicing functionality. Check 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 your main target market requires?
- Can your software generate Peppol BIS Billing 3.0 when you send via Peppol?
- Do you have a strategy for hybrid formats (Factur-X/ZUGFeRD) if your customers operate 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 still wise to know which format your software uses and why it fits your customers, so you can ask the right questions when a customer requires a specific format or rejects an invoice.
For integrators
The focus is on 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 trace back to EN 16931, conversion is feasible in terms of content, provided you account for the additional rules of the relevant CIUS.
Further reading
What is EN 16931: the European standard behind all formats. What is Peppol: the network for which Peppol BIS Billing 3.0 was developed. Looking for a Peppol Service Provider that supports the right formats for your software or customers? Compare Peppol Service Providers on peppol.nu.
