The ZRE and the OZG-RE are functionally similar for invoice issuers and for invoice recipients. However, the group of affiliated invoice recipients is different.

The ZRE is the mandatory central invoice receipt platform for the institutions of the direct Federal Administration. The OZG-RE, on the other hand, is an optional service offered by the Federal Government; it forwards invoices to affiliated institutions of the indirect Federal Administration, affiliated beneficiaries and cooperating federal states.