Since 2025, a public authority that is about to procure a new case management system, an e-office (sede electrónica) or a data platform has faced a preliminary step that hardly anyone takes yet: the interoperability assessment under Regulation (EU) 2024/903, the Interoperable Europe Act. The regulation has applied since 12 July 2024, and its articles on the assessment, the competent authorities and the single point of contact have applied since 12 January 2025. It obliges public sector bodies to assess, before deciding on new or substantially modified binding requirements for a trans-European digital public service, how those requirements will affect cross-border interoperability, and to publish the outcome. This guide explains, as at 16 September 2026, which services are covered, what the assessment contains, where it is published, how it relates to the National Interoperability Framework (Esquema Nacional de Interoperabilidad, ENI) that Spain’s public authorities already apply, and what changes in the tender specifications for custom software.

What is the Interoperable Europe Act?

Regulation (EU) 2024/903 of 13 March 2024 creates a cooperation framework so that Member States’ digital public services work with one another: an Interoperable Europe Board, a single portal for solutions and a catalogue of Interoperable Europe solutions (specifications, data models, reusable components) that public bodies can adopt. The part that is mandatory for every public authority is the interoperability assessment under Article 3, which turns what was until now good practice into a formal requirement: thinking about interoperability before deciding what a system will be like, not after building it.

Each Member State had to designate one or more competent authorities and a single point of contact by 12 January 2025, with responsibility for coordinating the application of the regulation and for supporting public bodies with their assessments. Each country’s designation is published through the Commission’s portal; it is worth checking there which Spanish authority is the relevant one before starting an assessment.

Which services it applies to

The obligation applies to trans-European digital public services: digital services provided by public sector bodies that require interaction across borders within the Union, between bodies in different Member States or with citizens and businesses in other Member States, by means of their network and information systems. They include, for example, services connected to the single digital gateway, those that exchange data through the evidence exchange system (the “once-only” principle), registers that are consulted from other Member States, electronic identification under eIDAS and public procurement procedures open to European bidders.

A purely internal case management system in a local council is not, in itself, a trans-European service; but it is one to the extent that it connects to European identification, to the exchange of evidence or to a register that can be consulted from abroad. That is why the question is not whether the system is “European”, but whether any of its binding requirements affects a cross-border interaction.

When the assessment has to be carried out

Before the public body takes a decision on new or substantially modified binding requirements for a service of this kind: rules, technical specifications, or the conditions of a contract or of tender specifications that determine how the service will be provided. Tender specifications for the development or supply of software that set formats, protocols, data models or interfaces for a trans-European service are a binding requirement, and the assessment must have been carried out before they are approved. If another public body has already carried out an assessment for equivalent requirements, it can be reused.

What the assessment must contain

Article 3 and the annex to the regulation set the minimum content, which can be summarised under four headings:

  1. A description of the service, the planned requirements and the public bodies, citizens and businesses affected, including those in other Member States.
  2. Effects on cross-border interoperability: how the requirements will affect the exchange of data and the provision of the service across borders, at the legal, organisational, semantic and technical layers of the European Interoperability Framework.
  3. Solutions considered: which Interoperable Europe solutions, European specifications or standards have been taken into account and which are being adopted, and why others have been ruled out.
  4. Consultation: with interested parties, including end users, where relevant.

The outcome is set out in a report in a common format established by the Commission and is published on the Interoperable Europe portal and on the public body’s website, in a machine-readable format. The assessment does not bind the public body to any particular solution, but it does oblige it to have considered interoperability and to explain how.

How it fits with the National Interoperability Framework

Spain’s public authorities have been applying the ENI (Royal Decree 4/2010, Real Decreto 4/2010) and its Technical Interoperability Standards (Normas Técnicas de Interoperabilidad) since 2010: electronic documents and case files, the catalogue of standards, signature policy, digitisation, reuse of resources and data intermediation. The European regulation does not replace it: it adds the cross-border dimension and the duty to assess and publish. In practice, a system that complies with the ENI has most of the semantic and technical layers dealt with at national level; the European assessment makes the public body ask, in addition, whether the formats, identifiers and protocols chosen are the ones that make it possible to interoperate with other Member States, and give preference to the solutions in the European catalogue where they exist. We set out how a case management system has to meet the ENI’s Technical Interoperability Standards in what a custom case management system must comply with.

What changes in the tender specifications for custom software

  1. The assessment comes before the specifications, and the specifications cite its outcome: the standards, data models and interfaces the assessment has identified become requirements of the contract.
  2. Open and European standards by default: specifications from the European Interoperability Framework, common vocabularies and data models (the Core Vocabularies, for example), and formats from the ENI’s catalogue of standards.
  3. Documented interfaces: published APIs and web services, with schemas and examples, so that other public bodies, including those in other Member States, can integrate with them.
  4. Reuse: a preference for existing interoperability solutions, and publication of new ones where the public body is able to do so.
  5. Electronic identification and signature compliant with eIDAS and ready for the European Digital Identity Wallet.
  6. Open, reusable data where the service generates it, aligned with the public sector’s open data obligations.
  7. Accessibility, which forms part of the organisational layer of interoperability, in accordance with Royal Decree 1112/2018 (Real Decreto 1112/2018), as we explain in web accessibility in the public sector.
  8. Contract exit with handover of the data, models and documentation in open formats, so that interoperability does not depend on the supplier.

A supplier that already works with the ENI and with open standards does not need to change the way it builds systems; it needs the tender specifications to ask for it and the assessment to justify it.

How CEDESA does it

CEDESA develops custom software for the public sector: case management systems, e-offices and data platforms for provincial councils (Diputaciones) and local councils, compliant with the ENI and its technical standards, with documented interfaces and open formats. That approach is what the Interoperable Europe Act asks public bodies to justify with a prior assessment, and we can help the public body prepare it, working from the specific project. Because we hold medium-category certification under the National Security Framework (Esquema Nacional de Seguridad, ENS), plus ISO 27001 and ISO 9001, the technical documentation that the assessment and the tender specifications require is part of our development cycle; and for innovation projects, public procurement of innovation – the route we describe in how to tender a development that does not yet exist – also requires interoperability to be thought through from the start.

Frequently asked questions about the interoperability assessment

How long has the interoperability assessment been mandatory?

Since 12 January 2025. Regulation (EU) 2024/903 has applied since 12 July 2024, and its provisions on the interoperability assessment, the competent authorities and the single point of contact took effect nine months later.

What is a trans-European digital public service?

A digital service provided by public sector bodies that requires interaction across borders within the Union, between bodies in different Member States or with citizens and businesses in other Member States, by means of their network and information systems: services connected to the single digital gateway, to the exchange of evidence or to eIDAS identification, or registers that can be consulted from other Member States.

When does the assessment have to be carried out?

Before the public body takes a decision on new or substantially modified binding requirements for a trans-European digital public service, including the technical requirements in tender specifications. An existing assessment by another public body for equivalent requirements can be reused.

Where is the interoperability assessment published?

The report, in the common format set by the Commission, is published on the Interoperable Europe portal and on the public body’s website, in a machine-readable format, so that other public bodies can reuse it.

Does the European regulation replace the National Interoperability Framework?

No. The ENI and its technical standards remain mandatory for Spain’s public authorities; the regulation adds the cross-border dimension, the duty to assess and publish, and a preference for European interoperability solutions where they exist.

Conclusion

The Interoperable Europe Act turns what public sector software procurement should always have done into a formal obligation: assessing and publishing, before requirements are set, how they will affect interoperability with other Member States, and giving preference to common standards and solutions. For a public body that already applies the ENI, the change is one of method and documentation, not of technology; for tender specifications, it means that the assessment comes first and the contract cites its outcome. If you are about to tender a system that connects beyond your own organisation, tell us what the service is and what it connects to.