As recognised in Directive 2014/55/EU on electronic invoicing in public procurement, ensuring interoperability brings significant benefits in terms of efficiency, cost reduction, environmental sustainability, and administrative simplification, making interoperability a key enabler for the success of eInvoicing across the European Union.
The European eInvoicing standard on eInvoicing (EN 16931) defines the semantic data model, supported syntaxes, and transmission guidelines necessary to ensure consistent understanding and processing of invoices between senders and receivers. These specifications align with the European Interoperability Framework (EIF), the EU’s reference model for building interoperable digital public services.
With the entry into force of the Interoperable Europe Act (Regulation (EU) 2024/903), the EIF has been reinforced as a legal and strategic tool for promoting interoperability across the Union. Public sector bodies that define or revise binding requirements for digital services — such as the adoption or extension of eInvoicing mandates — are expected to take the EIF fully into account. Where such measures have cross-border implications, an interoperability assessment may be required to identify and address any legal, organisational, semantic or technical barriers to effective implementation.
The EIF defines four layers of interoperability that remain central to the design and deployment of eInvoicing systems across the EU.
| Layer | Description in relation to eInvoicing and the European eInvoicing standard (EN 16931) |
|---|---|
| Legal | Legal interoperability ensures that electronic invoices are recognised as legally valid documents both within Member States and across borders. This includes compliance with legal requirements in areas such as VAT, accounting, and public procurement.
Together, these directives ensure that electronic invoices have the same legal validity as paper invoices and establish a common legal framework across the EU, particularly for cross-border procurement, resulting in better interoperability. |
| Organisational | These are the internal work processes of the seller and the receiver. Organisational interoperability relates to how business processes are structured and executed between the sender and the receiver.While the European eInvoicing Standard (EN 16931) does not attempt to harmonise internal business processes, it supports organisational interoperability by defining a common data model. This model reflects widely used business practices and allows for sector- or country-specific extensions to accommodate specialised workflows. |
| Semantic | Semantic interoperability ensures that the meaning of the information exchanged remains consistent and unambiguous for all parties involved. In practice, this means “what is sent is what is understood.”
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| Technical | Technical interoperability concerns the IT systems, applications, and infrastructures used to exchange invoices. It includes aspects such as system interconnection, data exchange, secure communications, and interface compatibility. The European eInvoicing Standard contributes to technical interoperability through:
While interface specifications are not defined by the standard, its supporting artefacts can be aligned with Interoperable Europe solutions to enable consistent implementation. |
These layers are further supported by governance tools introduced by the Interoperable Europe Act, including the Interoperable Europe Board, responsible for updating the EIF and recommending reusable interoperability solutions, and the Interoperable Europe Portal, which was created to host such solutions and related documentation.
Together, the European eInvoicing standard, the EIF, and the Interoperable Europe Act provide a comprehensive and legally aligned foundation for Member States to implement effective, scalable, and interoperable eInvoicing frameworks across the EU.
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