The paper provides a historical, substantive and functional analysis of the legal regulation of deposit insurance systems (hereinafter referred to as DIS) in the European Union based on Directive 2014/49 / EC of the European Parliament and of the Council of April 16, 2014. “On Deposit Insurance Systems” (revised). The author considers the contribution of DIS to improving the financial stability of the EU banking sector. The paper shows a conducted assessment of the measures implemented and planned for implementation initiated by the European Commission and the European Central Bank for the implementation of a single European DIS as the third pillar of the Banking Union. The author concludes that the third Directive “On DIS” allows for a qualitative step forward towards the creation of the third pillar of the Banking Union. Despite some unresolved and controversial issues, it creates uniform rules of the game for national DIS in a deposit insurance policy. Further development and movement towards European DIS will make it possible to increase the effectiveness of the EU deposit insurance policy by reducing costs, overcoming administrative barriers in national DISs, increase the level of protection of depositors’ rights, and strengthen confidence in the banking sector and its stability.