In order to ensure macroeconomic stability and the sustainability of public finances in the European Union, a system for coordinating the economic and fiscal policies of member states has been established at the European level, i.e., a set of rules and procedures based on the Stability and Growth Pact. Despite the obligation to participate in the coordination system, member states often face fiscal problems, leading to the assumption that they are not equally consistent in applying European rules and procedures, or that the coordination mechanism does not have the same level of impact on the fiscal policies of all member states. Therefore, this paper analyzes the fiscal aspect of the coordination system, i.e., its impact on the fiscal policies of member states. The emphasis is placed on the institutional and structural elements of national fiscal policies that can be considered as general assumptions for achieving successful fiscal outcomes. A comparative analysis of the impact of the coordination mechanism on national fiscal policies through three channels has generally shown: 1) that the impact has been significant in terms of improving institutional frameworks, as all member states have established appropriate fiscal rules and created independent fiscal institutions; 2) that it has also been significant in the implementation of specific recommendations related to structural measures in the broader field of public finance; while 3) it has not been significant in maintaining public debt and budget deficits within the prescribed limits of 3% and 60% of GDP due to the frequency of budget deficits and the intensity of borrowing. In the case of Croatia, however, the impact of the EU coordination mechanism on national fiscal policy has been significant in all three channels.