In today's global digital economic environment, there is a big demand for fast and effective transmission of data and information. Electronic invoicing (e-Invoicing) is a new form of electronic billing that replaces obsolete paper documents with electronic ones. This process increases the transparency of business transactions and bridges the accounting systems of suppliers and their customers in real time. The benefits of e-Invoicing can be seen such as in a better collection of receivables, reduction of printing and postage costs, cheaper and quicker processing and payment of the invoices. Consequently, external auditors and state authorities will be better able to track all issued and received invoices, paid and received cashless payments and, of course, financial authorities will be able to collect direct and indirect taxes more efficiently. The current paper deals with the adoption process of e-Invoicing within the European Union member countries from the viewpoint of B2G contracts. The process of adopting e-Invoicing is based on Directive 2014/55/EU on electronic invoicing in public procurement. Its goal is to ensure an interoperable standard for e-Invoicing in public procurement within the EU, reduce obstacles in cross-border procurement activities and ensure that business transactions between companies are more transparent. The main aim of the paper is to find out which EU member countries have complied with this directive and to subsequently compare the e-Invoicing rules valid in all EU member countries. For the purposes of this paper, we analyzed 28 EU member countries and 3 European Economic Area countries with the aim to present all findings. We analyzed EU member states’ electronic invoicing data published by the European Commission and by all European Union member states. We also analyzed the EU and EEA country fact sheets. We prepared a comparative analysis and found out the ratio between countries that do and do not comply with the Directive 2014/55/EU. However, the main aim of this Directive is to ensure adherence to the interoperable e-Invoicing standard. Many EU member states still have a unique approach to dealing with e-Invoicing. The existing e-Invoicing platforms differ and are operated by government institutions, public companies or private operators in the EU. More than 32 % of the countries included in the research sample still have no valid legislation regulating e-Invoicing. B2G e-Invoicing is voluntary in more than 38 % of EU member countries or EEA countries. Unfortunately, these countries still do not comply with the EU Directive.