In recent years, new emerging wireless technologies necessitate more spectrum resources compared to before. Related to this fact, cognitive radio and its capabilities provide promising functionalities in efficient management of the spectrum. In this paper, to maximize both spectrum utilization and revenue of network operators, we propose an Instant Overbooking Framework for Cognitive Radio networks (IOFCR) where different overbooking policies can be employed. Besides, the framework includes policies in order to decide which requesting secondary users (SUs) can be denied and which Active SUs can be ejected when a primary user (PU) activity is sensed. The effects of different pricing strategies used in a booking interval are also analyzed. To evaluate IOFCR, we use performance measures such as total net revenue, spectrum utilization, overbooking limit, number of free blocks, average service period, percentage of denied SUs forwarding their booking request and percentage of ejected Active SUs. In addition to being a first overbooking framework for Cognitive Radio Networks that takes several system parameters like PU on-rate, Active SU on-rate and Requesting SU show-rate into the account, to the best of our knowledge, this paper makes key contributions concerning the pricing policies, denial of requesting SUs, ejection and priority levels of active SUs. Finally, we numerically analyze the IOFCR performance by conducting numerous simulations and show the efficiency and validity in accordance with comprehensive measures mentioned above. (C) 2014 Elsevier B.V. All rights reserved.