You need an EORI number if you are an economic operator, that is, a person who, in the course of his or her business, is involved in activities covered by the customs legislation (Article 5(5) of the Union Customs Code (i.e. Unionszollkodex – UZK)).
“Persons” are either natural or legal persons (for example, an AG or a GmbH) or multiple persons with legal capacity (in particular partnerships such as GbR, OHG, or KG).
Persons who “in the course of business are involved in activities covered by customs legislation” are not only all those directly involved (for example exporters, declarants, representatives) but also all those indirectly involved, and in particular those taking part in the IT-assisted ATLAS procedure, even if they do not have a technical role (as, for example, someone transmitting technical messages). EORI numbers are issued free.