This monograph presents an in-depth analysis of internal control systems within organizations, with a focus on the COSO and COBIT frameworks. It aims to identify the sufficiency and areas for improvement in the internal control systems of selected accounting units. The study employs a multidimensional approach, examining the theoretical underpinnings of internal control systems, comparing them with practical implementations, and offering actionable recommendations. Through a case study approach, the monograph evaluates the internal control system of a selected accounting unit, identifying shortcomings in its control environment and suggesting improvements. The study found that while the accounting unit's management is committed to improving internal controls, there is often a reactive rather than proactive approach to issues.