Fraunhofer FOKUS Fraunhofer FOKUS Fraunhofer FOKUS This document describes policy-based accounting which is an approach to provide flexibility to accounting architectures. Accounting policies describe the configuration of an accounting architecture in a standardized way. They are used to instrument the accounting architecture and can be exchanged between AAA entities in order to share configuration information. This document describes building blocks and message sequences for policy-based accounting in the generic AAA architecture [RFC2903]. Examples are given for the usage of accounting policies in different scenarios. Furthermore it is shown how accounting components can be integrated into the AAA authorization framework [RFC2904]. This document does not propose a language for the description of accounting policies. It is rather assumed that a suitable policy language can be chosen from existing or upcoming standards.