This article used theorists to reinforce data on the effectiveness of the Internal Control System as an instrument that regulates public pension expenditure for Accountabilty. This topic allows the understanding of the importance of internal control as a practice that helps in the quality and results of an organization, because Accountability represents the obligation of accountability for the performance of a work from the responsibility of a delegated authority. How much and how the Internal Control System can assist the manager in decisions? The general objective is to analyze the effectiveness of the internal control system in order to serve pension institutions more effectively. The methodology was bibliographic, exploring magazines and websites, besides the Brazilian legislation; the data collection was carried out at the Public Servants Welfare Institute of the State of Rondônia (IPERON). It was possible to conclude that it is necessary for IPERON's Internal Control Sector to develop its activities according to its mission and vision so that qualitative results have priorities.