The Once-Only Principle Project

The Once-Only Principle Project (TOOP) was launched by the European Commission in January 2017 as an initiative of about 50 organisations from 20 EU Member States and Associated Countries. The main objective of TOOP is to explore and demonstrate the once-only principle across borders, focusing on data from businesses. Doing this, TOOP wants to enable better exchange of business related data or documents with and between public administrations and reduce administrative burden for both businesses and public administrations.


TOOP implements multiple sustainable pilots by using a federated IT architecture on cross-border, pan-European scale. Its aim is to connect registries and e-Government architectures in 21 countries across Europe. The solutions will be based on already existing systems in Member States and Associated Countries.


Businesses will benefit from the solutions developed by TOOP as they will be able to fulfill legal obligations by reduced administrative burden, time- and cost-savings. At the same time, the data that have been provided to public administrations will always remain under full control and consent of the businesses involved, in line with EU data protection legislation.

Administrations will achieve time and cost savings through administrative efficiency and will be able to offer improved service quality to businesses. Thus, administrations will profit from a better-functioning digital single market with increased customer satisfaction and a better image of public authorities.