The publication attempts to provide a comprehensive analysis of social security contributions in Polish law. It covers contributions that operate based on the Act on the Social Insurance System, as well as those that operate based on other legal acts. The research was carried out primarily from a legal and financial point of view. However, the study does not disregard considerations related to other branches of law. The author has not limited himself only to the analysis of the applicable regulations; he has also referred to previous regulations and described the origins of the various types of contributions. The publication makes an extensive use of the extensive achievements of the doctrines of public finance law (including tax law) and labour law. The publication not only presents current legal solutions on social security contributions in Polish law, but it also formulates de lege ferenda conclusions.