The Once-Once Principle (OOP) suggests that citizens and businesses should have the right to supply information only once to a public administration. It would then be the responsibility of public administration offices to take all necessary actions in order to internally share this data by respecting the relevant data protection rules. The overall aim is to reduce administrative burden. The implementation of the OOP is high on the political agenda of many countries including the Member States of the European Union. The aim of this panel is to enable an open discussion between the panelists and the audience in order to exchange good practices and also identify and prioritize benefits and barriers as well as possible next steps towards widely implementing the once only principle in public service provisioning.