AbstractThe ambiguous trends in international trade in 2019 and the forecast for 2020 enhance the functional role of the customs bodies in every country. That is because the customs system largely determines the ease of conducting international trade, the security of international supply chains and economic development of the countries. Though many developed countries have been able to form progressive customs systems, there are still countries that are in the process of reforming customs administrations and require a unified conceptual approach to build their customs systems. Given this fact the goal of our study is to analyze current trends in the development of the international customs systems and on the basis of it to identify the main and support functions of customs administration. Based on the principle of the best practices, the countries with the best customs administrations according to WTO data, i.e. France, Germany, the Netherlands, Lithuania and Poland were selected for analysis. We analyzed the positions of these countries in the leading international rankings, the key quantitative indicators of their customs activity and the peculiarities of the organizational construction of the customs authorities by functional principle. As the result, based on the use of systematic, dynamic and topologically substantive approaches and results of research, we developed a unified conceptual structure of the customs administration. In particular, the main functions (i.e. control, security and fiscal) and support functions (i.e. regulatory, administration, communication, service, information and statistical subsystems, resource support subsystem and international cooperation) were proposed. The proposed structure is intended to be used by representatives of the customs authorities in different countries throughout the world.