Security deposit is refundable in 30 days. It is requirement not only from car renal company but also from UAE government. From deposit amount will be deducted RTA (Roads and Transport Authority) fines, salik, cost of damages (if insurance refuses to cover) and also in a case of theft of a car. 30 days duration is necessary because RTA and Police reports are coming not in the moment of action but delayed at least for 14 days.