The invention relates to the field of mobile communication systems. In particular, the invention discloses a method for handover decision making during an inter-radio access technology (RAT) handover. According to the method, the decision for inter-RAT handover may be taken by the serving network entity in a hierarchical manner beginning with a radio access network (RAN) entity and proceeding towards a core network (CN) entity. Further, the serving network entity may take the decision for the inter-RAT handover based on the information and knowledge of the target access system handover criteria and the ranking available in the network entity.