It is therefore clear, for example, that the management of an airport (economic activity) implies providing a customs service to check the identity of passengers, although it should be noted that such a service is one of the tasks traditionally reserved to the State and is therefore a non-economic activity.
Selon la Belgique, la séparation comptable est garantie par l'application de l'article 25 du cahier des charges qui dispose que le «concessionnaire tient un compte d'exploitation distinct pour les Services.