Page tree






Europe is making life easier

for cross-border Citizens and Businesses

Photo by fabio on Unsplash










The Once Only Principle (OOP) technical system is an EU-wide initiative driven by the European public sector as part of the Single Digital Gateway Regulation (EU) 2018/17241.


The OOP technical system will enable Member States to request data from competent authorities in other Member States in order to simplify access to cross-border administrative procedures initiated by citizens or businesses. The procedures covered by this system include everyday transactions such as registering the change of address and of a car when moving abroad, starting a business in another Member State or cross-border academic recognition. Following the use of the Once Only Principle, the competent authority providing the data acts as a Data Provider, while the competent authority receiving the data acts as a Data Consumer.

According to the regulation, the OOP Technical System should become operational by December 2023. This leading-edge system, will ultimately lead to greater governmental collaboration in the EU thanks to faster and cheaper online verification processes with the same level of trust, or even higher, than everyday traditional paper-based checks.


How will the OOP Technical System work?

The generic Use Case of the OOP technical system is relatively simple. While carrying out a cross-border administrative procedure online, evidences relating to a citizen, or a represented business, may be required about the place of birth, place of residence, etc. The Once-Only technical system will allow governmental portals, and similar websites, to request data from one or several other competent authorities in (a) different Member State(s), for use in the context of a specific administrative procedure following an explicit request by the Citizen.

This means that the OOP system aims at enabling Government-to-Government (G2G) cross-border data sharing at all administrative levels (local, regional and national) leading to the creation of a EU-wide data space for public administrations involving many data providers and many data consumers. In other words, the OOP Technical System will become tpart of the foundation of a secure and trusted data sharing system among public administrations across the EU.

How is Europe going to create this system?

The European Commission is working in close cooperation with all EU Member States to make this system a reality. An important contribution to this effort will come from the The Once Only Principle (TOOP) large-scale pilot. This Horizon 2020 funded pilot project – initiated in January 2017 to prepare for the application of an EU wide regulatory and technical OOP infrastructure – provided participating organisations the opportunity to test, the kernel of the architecture and technology necessary for implementing the OOP Technical System. This pilot took place in operational conditions with actual systems running in the Member States and associated countries. As this pilot ends, its results will be an important input to the ongoing work to build the OOP Technical System. The TOOP Web conference on 23 September 2020 provided a unique opportunity for the wide public to learn about TOOP’s achievements.