The article is devoted to the issue of a misdemeanour in Article 98 of the Polish Act on the social insurance system. The author presents the genesis of this legal regulation, and then proceeds to justify the thesis about the need to transform this offense into a crime. In this regard, account is primarily taken of the fact that the fiscal interest of the State is protected both in tax law and under fiscal criminal law. On the other hand, protection of the interests of the Social Insurance Institution and the insured, including the social insurance system in the area of criminal law does not seem to be consistent with the law protection of taxes. In addition, specific changes to the provision of Article 98 of the Polish Act on the social insurance system are presented, which are to improve the prosecution of perpetrators of acts described under this regulation.