Public service obligation

A public service obligation (PSO) is a requirement placed on a port, ferry operator, or inland-transport provider to deliver a service that is socially necessary but not commercially viable on its own, in return for a defined subsidy or exclusive right. In maritime use it most often supports lifeline ferry routes to islands or remote coasts and certain non-profitable port services. In the EU it operates under maritime cabotage Regulation (EEC) No 3577/92 and the public-service-compensation rules, which limit aid to the net cost of the obligation. PSO arrangements appear in national port system plans where connectivity outranks pure profit.