Automated Teller Machine (ATM) service providers are increasingly challenged with improving the quality of customer service while reducing the cost of cash flow management. Effectively balancing the need to have enough cash in the ATMs to avoid out-of-cash incidents as well as to reduce the cash interest cost and the cash refill cost challenges the most experienced cash flow management teams. In this paper we propose an optimization framework for managing the ATM cash flow network. The interactions among various constraints and cost factors are included in the framework to allow decision-making regarding the optimal cash refill amount and schedule. We demonstrate the effectiveness of the proposed approach using sample data from a large commercial bank.