The standard EN16931 published on 28 June 2017 defines a semantic data model for a core invoice. The target group are public authorities as recipients of invoices, but this also affects the economy in general. EN16931 complies with the European Directive on electronic invoicing for public authorities (EN 2014/55 / ​​EU). It has been prepared by the Technical Committee TC434 at CEN by the European Commission.

The standard consists of several sections. The last sections have been published on October 17th 2017.

  • EN16931-1: 2017, Electronic invoicing – Part 1: Semantic data model of the core elements of an electronic invoice
  • CEN / TS 16931-2: 2017, Electronic invoicing – Part 2: List of syntaxes that comply with EN 16931-1
  • CEN / TS 16931-3-1: 2017, Electronic invoicing – Part 3-1: Methodology for syntax bindings of the core elements of an electronic invoice
  • CEN / TS 16931-3-2: 2017, Electronic Invoicing – Part 3-2: Syntax binding for ISO/IEC 19845 (UBL 2.1) invoice and credit note
  • CEN / TS 16931-3-3: 2017, Electronic Invoicing – Part 3-3: Syntax binding for UN/CEFACTXML Cross Industry Invoice D16B
  • CEN / TS 16931-3-4: 2017, Electronic Invoicing – Part 3-4: Syntax binding for UN/EDIFACT INVOIC D16B
  • CEN / TR 16931-4: 2017, Electronic invoicing – Part 4: Guidelines on interoperability of electronic invoices at the transmission level
  • CEN / TR 16931-5: 2017, Electronic invoicing – Part 5: Guidelines on the use of sector or country extensions in conjunction with EN 16931-1, methodology to be applied in the real environment
  • CEN / TR 16931-6, Electronic invoicing – Part 6: Result of the test of EN 16931-1 with respect to its practical application for an end user – Testing methodology

Implementation deadlines

According to the Directive, public authorities have fix implementation periods in order to transform the requirements of the standard and the Directive in both national law and a live operation. On the one hand, the Directive defines fixed dates, as well as flexible periods, if the standard is not published in time. However, the reference date for the time account is not the publication of the standard itself, but the reference to it in the Official Journal of the European Union. The EN16931 has been published with a slight delay. 

The European Commission referenced the first two parts on 17 October 2017 in its official journal. With the publication, central contracting authorities now have 18 months to implement the requirements. For decentralized contracting authorities, the deadline may be extended by 12 months to 30 months. This leads to the following deadlines:

  • Central public authority: April 18 2019
  • Decentralized public authorities: April 18 2020

Usage specifiaction of EN16931

The semantic data model of the European standard contains many optional elements. By creating a usage specification for the core invoice model (CIUS), a Member State, user group or organization determines which of these optional elements are required. Such definitions are always used to optimize the processing of invoices. Examples of such requirements can be the transmission of a customer number, an order number or a cost center.

EN16931 defines rules for the preparation of such usage specifications. A specification that is compliant with EN16931 may neither add new information nor violate existing business rules. However, such specifications may specify exactly how to bypass optional fields. An overview of the currently known CIUS can be found on this page.

Extensions to EN16931

EN16931 defines a model only for the core processes of an electronic invoice. For example, the data model supports only invoices with reference to a maximum of one delivery note and a maximum of one purchase order. In practice, therefore, the invoices that combine several deliveries or orders are not directly supported. For such situations, an invoice per delivery and purchase order would have to be created, which could lead to a multiplication of the accounting documents.

Therefore, some organizations have decided to expand the European data model accordingly.

For this purpose too, EN16931 defines rules by which a conformant extension of the data model can be defined. At present, the CEN TC 434 will expand its scope at European level. The date of their completion is not yet foreseeable. However, some organizations are already beginning to develop extensions.

An overview of the current extensions can be found on this page.