Anyone dealing with electronic invoices will sooner or later come across the term EN 16931. It is behind almost every e-invoicing format used in Europe, whether XRechnung or ZUGFeRD.

EN 16931 is a European standard that defines a semantic data model for electronic invoices.

EN 16931 is the European standard for the semantic data model of an electronic invoice. It specifies which information an invoice must contain and how this information is structured, but it does not prescribe a specific file format. The standard is developed by the European Committee for Standardisation, or CEN (Comité Européen de Normalisation), more precisely within the responsible technical committee CEN/TC 434. It is a multi-part standard, of which the first part, EN 16931-1, describes the actual core invoice model.

EN 16931 specifies the semantic data model for electronic invoices. It aims to create a common European standard for the electronic exchange of invoices, enabling interoperability between different software systems and across national borders.

The standard defines which details must be included in an invoice, such as invoice number, date, amounts, tax rates, or details of the buyer and seller, and how these details logically relate to each other. This is called a semantic data model because it defines the meaning of the individual invoice components, regardless of the technical file format in which the invoice is ultimately transmitted.

This technical file format, known as the syntax, is deliberately kept separate. EN 16931 has been specified for the UBL (Universal Business Language) and CII (Cross Industry Invoice) syntaxes. Simply put: the data model describes what must be in the invoice, and the syntax describes how the whole thing is structured as a concrete file.

Since when has EN 16931 existed?

The standard is not a new invention. The original version, EN 16931-1, was adopted back in 2017 and has since served as the basis for the first e-invoicing formats in Europe. On this foundation, public administrations in the EU have had to be able to receive electronic invoices since 18 April 2019, which was a direct consequence of the underlying EU Directive 2014/55/EU. This obligation initially only applied to the receipt of invoices by public sector authorities, not to their transmission by businesses in commercial transactions with each other.

In 2026, the standard underwent a major revision, resulting in the current version, EN 16931-1:2026.

Was ist ein CIUS?

CIUS stands for Core Invoice Usage Specification. This refers to a nationally adapted, restricted version of the European core standard. A CIUS must not alter or contradict the rules of the core standard, but it may make certain fields mandatory, restrict them, or supplement them with country-specific requirements. This ensures that any system that supports the full core standard can also process invoices created according to a specific CIUS.

XRechnung is precisely such a CIUS, the German implementation of EN 16931 tailored to the public sector, including the routing ID required in Germany. Other countries have their own CIUS variants with their respective national specificities.

EN 16931 applies to all EU member states.

As the standard was introduced via EU Directive 2014/55/EU, the obligation to accept EN-16931-compliant invoices in the public sector has been in effect in all EU member states since 2019. However, how individual countries specifically implement this in the B2B sector between businesses, and with which own CIUS, differs considerably, and this area is currently undergoing very dynamic change across Europe.

Here are a few examples to put this into context: Germany is implementing its own CIUS with XRechnung. Belgium and Croatia have already introduced their own B2B requirements, whilst France is set to introduce its own later this year; each country is following its own timetable and, in some cases, utilising the international Peppol network. Some countries have not defined their own CIUS, but instead use the internationally agreed Peppol BIS specification directly.

XRechnung, ZUGFeRD and Factur-X differ in their origins, technical specifications and the level of detail they support. **XRechnung** is the German national standard for electronic invoices (e-invoices). It is based on the European standard EN 16931 and is mandatory for B2G (business-to-government) transactions in Germany. XRechnung focuses on structured data and is designed for automated processing. It is a pure data format, meaning it doesn't include a visual representation of the invoice itself. **ZUGFeRD** (ZUGFeRD stands for "Zentraler User Guide des Forums Elektronische Rechnung Deutschland") is also a German standard, but it is more flexible than XRechnung. ZUGFeRD is a hybrid format that combines a structured data component (following EN 16931) with a human-readable PDF/A-3 file. This means a ZUGFeRD invoice is both machine-readable and visually displayable in a single file. It supports different profiles, allowing for varying degrees of data detail. **Factur-X** is a French-led initiative, also based on EN 16931. Like ZUGFeRD, it is a hybrid format that embeds structured data within a PDF/A-3 file. Its primary goal is to facilitate cross-border electronic invoicing within the European Union. Factur-X aims to be interoperable and is designed to be compatible with other national standards that adhere to EN 16931. **Key differences summarised:** * **Origin:** XRechnung (Germany), ZUGFeRD (Germany), Factur-X (France, broader EU initiative). * **Format:** XRechnung is a pure data format. ZUGFeRD and Factur-X are hybrid formats (data + PDF). * **Flexibility:** ZUGFeRD and Factur-X offer more flexibility with different profiles/levels of detail compared to the stricter XRechnung. * **Scope:** XRechnung is primarily for German B2G. ZUGFeRD and Factur-X are designed for broader B2B and cross-border use within the EU. * **Interoperability:** ZUGFeRD and Factur-X are strongly oriented towards interoperability, aiming to work seamlessly across different systems and countries, while XRechnung is more specific to the German regulatory framework.

All three formats are based on the same European data model (EN 16931), but they differ in terms of which country and use case they are intended for, and how the invoice is technically transmitted.

XRechnung The German CIUS, solely as a pure XML file, was originally developed for the public sector. ZUGFeRD and the closely related, European-focused Factur-X follow a hybrid approach: they combine a human-readable PDF with embedded, structured XML data, so that a human can open and read the invoice directly while software simultaneously processes the machine-readable data. Both methods are compatible with the same European standard, differing primarily in the transmission format and original intended use.

Wer ist für EN 16931 zuständig?

The European Committee for Standardisation: CEN (Comité Européen de Normalisation) is responsible. This is the official organisation that develops European technical standards across industries, not just for e-invoicing. Members include the national standardisation institutes of EU and EFTA countries, such as DIN for Germany. CEN decides on the content of the standard and its new versions before individual countries can develop their own CIUS based on them.

Is EN 16931 legally binding?

It depends on the context. The standard itself is initially a technical specification, not an independent legal obligation. It only becomes binding when laws and directives refer to it. In the public sector, this has been the case throughout Europe since 2019 via EU Directive 2014/55/EU. In the B2B sector, however, each country decides for itself whether and when to introduce its own obligation; in Germany, for example, this will be staggered from 2025, 2027, and 2028 as part of the national E-invoicing obligation. In the long term, the standard is also set to become mandatory for all intra-EU B2B transactions from 1 July 2030 as part of the European ViDA initiative.

What changes with EN 16931-1:2026?

The revision adopted in 2026 is the most comprehensive development of the standard since its introduction in 2017. The underlying data model is growing significantly, including features such as structured cash discount details and the ability to consolidate multiple orders into a single invoice. This revision is also the reason why Germany is simultaneously developing a new version of its own CIUS, XRechnung 4.0.

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