One of the main reasons for the system-parametric reform of the Polish social insurance in 1999 was the expected elimination of the deficit of the Insurance Trust Fund (FUS). The solutions implemented at that time included the separation of pension, disability, sickness and accident funds from FUS, and collection of separate contributions per each fund. Yet, as the reform started at that time has never been completed, its solutions caused decline of the system and its components, including sickness insurance, and the results that have been achieved are worse than before the implementation of the reform. The purpose of this paper is to present a scale of the funding deficit in sickness insurance, and to indicate actions aimed at improving its effectiveness through the use of a new financial tool the form of an Individual Social Security Account. The funding deficit in sickness insurance was analyzed in the paper using the method of economic analysis, document study and a measure of financial efficiency of the system. On the basis of the analysis the author presented possibilities of unifying the social security system by realizing the idea of individual anticipation, ensuring its coherence by obligatory application of the system rules and financial balance achieved by means of the proposed financial tool, and specific system and parametric changes.