One of the main tasks of IT business continuity planning (BCP) is to guarantee that incidents affecting the IT infrastructure do not affect the availability of IT-dependent business processes beyond a given acceptable extent. Carrying out BCP of information systems is particularly challenging, because it has to take into consideration the numerous interdependencies between the IT assets typically present in an organization. In this paper we present a model and a tool supporting BCP auditing by allowing IT personnel to estimate and validate the recovery time objectives (to be) set on the various processes of the organization. Our tool can be integrated in COBIT-based risk assessment applications. Finally, we argue that our tool can be particularly useful for the dynamic auditing of the BCP.