The Resource-Event-Agent (REA) ontology is a powerful and well accepted approach towards the design of accounting information systems (AIS). However, the REA notation - that is currently based on class diagrams - is not very intuitive for business experts. Accordingly, we aim at a REA domain specific modeling language that facilitates the communication between business experts and IT professionals. In previous work we defined the REA-DSL operational layer reflecting actual business events which “have occurred” or “are occurring”. In this paper we extend the REA-DSL by the planning layer capturing what future events “are scheduled” or “are planned” by commitments. Now, our REA-DSL covers all basic concepts to describe a full accounting infrastructure. The REA-DSL may serve as a solid basis for generating a conceptual AIS data model - which is subject to future work.