The topic of this paper is the County Treasury System as a business process in Požega- Slavonia County. Since this paper is based on the implementation of business processes, it defines them and shows the importance of good and quality management of business processes in both the private and public sectors. The first part of the paper presents the implementation of the budget planning process at both the state and local self-government units. It also provides an overview of the budget as a basis for performing higher business processes. Furthermore, the continuation of the work provides an overview of the operations of the treasury system. The paper defines the treasury system, presents its process of introduction at the state and at the level of local regional self-government units, brings its advantages and goals of introducing such a business system. The paper presents Požega- Slavonia County and its system of introducing the treasury system and the improvements achieved by the introduction of the treasury. The end of the paper brings a conclusion that refers to the overall conduct of business processes in the public sector and draws conclusions about what it means to manage business processes at all levels of government in a quality and transparent manner. It also brings the results achieved on the basis of good realization of the preconditions for the establishment of the treasury system.