Management Accounting in ERPI Systems Introduction In this competitive global economic environment, companies around the world are in dire need of increasing profits and reducing costs every year. They have tried many ways to improve their business, such as improving product quality, gaining more market share, and improving customers' feeling of satisfaction. These decisions, while simple, contain several thousand pieces of financial data that must be analyzed before any new decisions can be made. Within a company, management accountants are responsible for these decisions with their responsibilities, including "management decision making, devising planning and performance management systems." , and provide financial reporting and control expertise to assist management in formulating and implementing an organization's strategy.” (Institute of Management Accountants, 2008) . With all these responsibilities, many management accounts have encountered various problems, in particular in the collection of data, in their classification and therefore in their processing. However, new accounting information systems have allowed large corporations and management accountants to easily classify, collect, and standardize financial information. One of those powerful tools that has greatly helped management accountants to fully process and collect is Enterprise Resource Planning (ERP) system. Since 1990 ERP systems have revolutionized the way businesses make decisions, ERP has become an integral part of management accounting as it has helped managers efficiently use and analyze data and apply analytics to achieve business objective cost reduction and revenue increase. ERP systems have the capabilities...... half the paper...... and consumes the most resources, while driving the least profits. Therefore, management that only has complete information has difficulty making a precise and accurate decision about which product should reduce redundant costs and how to reduce costs. However, activity-based costing (ABC) could help make the function of enterprise resource planning (ERP) systems more integrity. Activity-based costing (ABC) not only assigns different cost drivers, but can also track costs incurred throughout the entire enterprise resource planning (ERP) systems cycle for individual products and services. By combining enterprise resource planning (ERP) and activity-based costing (ABC) systems, companies can have a comprehensive view of the entire company, as well as having a clear view of the details. USPS needs to develop ABC, while Elkay Plumbing benefits greatly from it