The main purpose of the article is a feature of the features of the legal support of the financial activity of socio-economic systems. The object of the study is the financial activity of socio-economic systems. The structure of the article provides for consistent actions through a review of scientific and practical literature, a presentation of the research methodology, a description of the results obtained and the conclusions drawn from them. It is proved that the successful functioning of the financial activity of the socio-economic system depends primarily on its legal support. It has been established that the main purpose of the financial department of such socio-economic systems as enterprises is to determine the needs of the enterprise for financial resources and the amounts necessary to fulfil the economic development plan of the enterprise; search for reserves to increase profitability; Increasing the profitability of activities The research methodology involves the use of methods of analysis and synthesis with a combination of the methodology of the hierarchical ordering of the main legal factors that affect the financial activities of socio-economic systems. The importance of analyzing the features of the legal support of the financial activity of socio-economic systems is proved. As a result of the study, a hierarchical ordering of the main legal factors that have a significant impact on the financial activities of socio-economic systems was presented. The study is limited by ignoring other components of the economic activity of socio-economic systems. Subsequent studies should be devoted to the study of the legal support of the information activity of socio-economic systems.