In this document, the general ICOS data policy principles are described. The aim of this data policy is to guarantee a smooth data flow from the ICOS RI National Networks, Central Facilities and Carbon Portal to the users to provide open, easy access to ICOS data and develop user-driven services for user communities (e.g. to scientists, national and international agencies, local authorities, general public). To achieve ICOS RI objectives, General Assembly of the ICOS ERIC has adopted this data policy and may amend it.