The subject of the final thesis is office business and correspondence. Public administration is an integral part of the broader notion of public administration, which, in addition to state administration, includes local and regional regional self-government and public services, whose common aim is to satisfy the general interests and public needs. Public services are public institutions and other legal entities that are provided with wage funds in the state budget. The aim of the paper is to define the basic concepts that are mandatory in the field of office business. This will define the office, writing, act, stamps and seals, etc. This paper explains the structure in the Republic of Croatia. This will clarify the bodies of state administration, legal entities performing legal affairs and expert services of the Government of the Republic of Croatia.