The article argues that the supreme audit institution, an independent entity at national level, whose external audit role is established by the Constitution, is traditionally recognized for verifying budgetary expenditures, in order to identify deviations from the principles of legality, efficiency, effectiveness and economy in the management of public funds. The principle of legality, based on which the public administration authorities and institutions have the obligation to act in compliance with the legal provisions in force, determines those responsible for public sector governance to fulfill their responsibilities correctly. The paper provides an overview of the involvement of the supreme audit institution in finding the reflection of the principle of legality in reporting the financial performance of public administration.