SUMMARY
The purpose of the paper is research of practice of making financial reserves of the state social insurance in Ukraine and determining their optimal size. The method of study allows finding how the financial reserves ensuring sustainability of the state social insurance over three years (2014, 2015, 2016). Methodology. The results of the study were obtained after analysing the indicators of the budget of state social insurance funds (2014, 2015, 2016). In the course of research, an analysis and synthesis as methods of theoretical knowledge of phenomena are used. Comparisons and measurements are used as empirical methods for the conducted research. Results of the research showed the lack of uniform methodological principles for the formation of financial reserves of state social insurance, which is confirmed by their various volumes, and the absence of the mandatory creation condition of them. Extrapolating the provisions of Article 14-3 of the Budget Code of Ukraine, we propose that the amount of cash in circulation should not exceed 2% of the budget expenditures of the state social funds, that is, to provide a seven-day need for financing the insurance payments. At the same time, the condition of keeping the amount of cash on hand at the end of the period (year) should become mandatory. Practical implications. For conducting research and substantiation of relevant conclusions, the indicators of budgets of the state social insurance funds of Ukraine for three years are analysed (2014, 2015, 2016). Value/originality. A step that will balance the financial resources of state social insurance is the need to introduce uniform requirements for the formation of financial reserves of state social insurance funds. The proposed measures will enable to make more manageable the system of the state social insurance funds in Ukraine.