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The history of electronic invoicing is closely linked to the history of information technology (IT). As there were still horses and carriages on the streets, first electronic messages were already being telegraphed to order flowers and invoice them. Similarly in the 1980s, electronic data exchange (EDI) got introduced in the automotive and consumer goods industries. The Internet era added new EDI transmission protocols (e.g. EDIINT AS2, AS4), formats (XML) and forms of service (software as a service, marketplaces). For most companies, this increased the complexity of connections, so that electronic messages were slowly becoming the bottleneck of what they should solve: the automation of the business processes.

In the 2000s, the European Union (EU) had already accompanied this development by creating the required legal framework. It had ensured that electronic signatures were valid throughout the EU (1999/93/EC) and had harmonized requirements for invoice content (2006/112/EC). Preparing next steps, the EU realized that, among market players, progress in digitalization actually increased interoperability issues. The variety of XML and EDI formats was steadily increasing. EDI service providers and marketplaces could not easily agree on contractual and technical issues... Some even refused to cooperate. "The multiplicity of non-interoperable standards results in excessive complexity, legal uncertainty and additional operating costs for economic operators", the EU stated[1].

This led to the launch of the Peppol (Pan-European Public Procurement OnLine) project in 2008. Over a period of 3-4 years, a group of experts met regularly in Brussels: participants were representatives from government IT departments, EDI service providers and industries. They listed the difficulties and worked out a solution. In 2010, this led to the creation of the openPeppol Association. openPEPPOL was meant to develop a legal and technical framework for the interoperability of providers. At the beginning of 2010, experiences from Norway and Denmark showed that a legal obligation in favor of one or two formats was creating a critical adoption mass. It also documented that this obligation had a 1000-fold effect if not only the invoice recipients were obliged, but also their suppliers

This again led the EU to formulate Directive 2014/55/​​EU. The directive stipulates that all EU contracting authorities must be able to receive electronic invoices[2]. In the context of the directive, the definition of electronic invoicing is limited to structured invoices[3]: "A mere image file should not count as an electronic invoice." Pure PDF files are therefore excluded. The EU left over further specifications to the European Committee for Standardization (CEN), which defined two syntaxes under the EN 16931 standard:


  • ISO / IEC 19845 (aka UBL 2.1)

This paved the way for national and regional implementations within the EU. Individual EU states could decide whether a supplier obligation should be introduced by law. The starting points of each EU state were very different and shaped their implementation decisions:

  • Austria, Denmark, France, Italy, Slovenia, Spain had introduced a legal supplier obligation (B2G[4]) for long. They had already mandated other syntaxes and syntax versions than those developed by the CEN. In practice, the EU norm got added to national ones. Some states like Denmark and Norway[5] planned and implemented a migration towards Peppol or the EU syntax and are now switching off their national formats. Other countries took more time.

  • Belgium, the Netherlands, Sweden and, last but not least, Germany had no B2G obligations in place. They could therefore use the EU standard as the basis for green-field programs. These countries defined the Peppol / UBL variant as their preferred syntax and the Peppol infrastructure as their preferred communication means, perfectly in line with the requirements of openPeppol. They also partially took steps towards supplier obligations.

Germany being a federal state, a supplier obligation by law had to be decided at the level of each individual German state. Currently, Bremen and Lower Saxony made such a decision along with the federal government.

Illustration: The milestones of electronic invoicing in Germany.


Some German states have decided against a legal obligation of suppliers. The decision is still pending in some states. An overview of the legal implementations at state level can be found on the website of the Coordination Office for IT Standards (KoSIT)[6]. The law firm PSP Munich describes the legal aspects and requirements for implementations with much detail in a German guideline [7].

Importantly, where there is no supplier obligation by law, suppliers may nevertheless face contractual obligations. When renewing a contract, contracting authorities are very likely to introduce clauses on electronic invoicing to include invoices under € 1,000 and enforce electronic invoicing in states without local obligations. To estimate invoice volume for a project, this is an important aspect. Furthermore, the European standards have been designed for use between businesses, so that you can consider requiring government formats from your suppliers or sending them to your business partners in replacement of paper invoices or EDI connections.

The second part of this series is about the German standard for electronic invoicing, XRechnung.


This series is drawn from the German blog XRechnung, ZUGFeRD und Peppol – Alles, was Sie über die elektronische Rechnung wissen wollen (und vi....


[2] There are some subtleties in the scope of the Directive. The obligation only applies to contracts that have to be advertised across Europe under EU law (so-called upper-threshold awards). States can expand the scope of their national and regional implementations beyond the scope of the Directive.

[3] Like in all other EU-states, in Germany, the regulation implementing the Directive on electronic invoicing for the federal government defines an electronic invoice as a document that is "issued, transmitted and received in a structured electronic format and [such] format enables automatic and electronic processing [...]." (ein Dokument, das in einem strukturierten elektronischen Format ausgestellt, übermittelt und empfangen wird und [dessen] Format die automatische und elektronische Verarbeitung [] ermöglicht).

[4] In the jargon of e-invoicing experts this is called a business-to-government obligation, inshort B2G.

[5] While Norway is not part of the European Union, it self-committed to Peppol and took a leading role in its promotion. Noticeably, Norway did NOT (have to) introduce the second CEN standard, UN/CEFACT XML.

[6] Overview by the KoSIT on the implementation of EU Directive 2014/55/EU (in German):

[7] The guideline has chapters on documenting invoicing processes in a process documentation and on archiving requirements. While it targets public services, the rules and definition compiles are applicable to businesses too: Peters, Schönberger & Partner München, Die elektronische Rechnung in der öffentlichen Verwaltung – Ein Leitfaden für die praktische Umsetzung (Version 1.4):