This document establishes a semantic data model of the core elements of an Electronic Invoice. The semantic data model includes only the essential information elements that an Electronic Invoice needs to ensure legal (including fiscal) compliance and to enable interoperability for cross-border, cross sector and domestic trade. The semantic data model can be used by organizations in the private and the public sector for public procurement invoicing. It can also be used for invoicing between private sector enterprises. It has not been specifically designed for invoicing consumers. This document complies at least with the following criteria: it is technologically neutral; it is compatible with relevant international standards on electronic invoicing; the application of this standard should comply with the requirements for the protection of personal data of Directive 95/46/EC, having due regard to the principles of privacy and data protection by-design, data minimization, purpose limitation, necessity and proportionality; it is consistent with the relevant provisions of Directive 2006/112/EC [2]; it allows for the establishment of practical, user-friendly, flexible and cost-efficient electronic invoicing systems; it takes into account the special needs of small and medium-sized enterprises as well as of sub-central contracting authorities and contracting entities; it is suitable for use in commercial transactions between enterprises.