In today's digital age, public services play a key role in meeting the needs of citizens. Digitization of public services and establishing interoperability between information systems is the key step in improving the process of providing public services. One of the key elements for achieving interoperability of the public administration system is the interoperability bus. The bus provides standardized mechanisms and services that enable different systems to communicate, exchange data and coordinate their operations at the national level. This paper explores various aspects of interoperability, from theoretical foundations to practical applications in the public sector. The concept of interoperability is analyzed, emphasizing the importance of standardization and compatibility between systems. Furthermore, the impact of interoperability on improving the quality of public services and the efficiency of administrative processes is studied. Special attention is paid to examples of good practice from different countries in the implementation of interoperable information systems. In addition, this paper explores the technical and organizational challenges associated with establishing interoperability and identifies key implementation challenges and barriers. Finally, the paper gives recommendations for further development and implementation of interoperable information systems in the public sector. In short, this paper emphasizes the importance of interoperability between information systems in improving the provision of public services to citizens. The implementation of interoperable solutions requires a multidisciplinary approach and cooperation between all levels of management and operational employees with technical knowledge, but the potential benefits in the form of more efficient and better services make the investment in the establishment of interoperability profitable in the long term.