In 2011, Eurostat estimated that some 12 million EU citizens were living in a Member State which was not their home country. Many more reside temporarily in another EU State, for example for purposes of study or work, or simply to take a holiday. All these people may potentially at some point come into contact with the administrative authorities of the country they are visiting or residing in – tourists with the health system, students with a university administration, workers with the tax and social insurance authorities, etc.
Ces personnes peuvent toutes à un moment donné être en contact avec les autorités administratives de l'État où elles séjournent: les touristes avec le système de santé, les étudiants avec les services administratifs des universités, les travailleuses et les travailleurs avec les autorités fiscales et la sécurité sociale, etc.