The aim of the article is to evaluate the legal solutions adopted in the Act of 13 February 2020 amending the Construction Law and some other acts in the field of legalization of unauthorized construction. The cited Act is another example of the legislator's activities aimed at reducing the number of illegal constructions in Poland. Contrary to the regulations which is currently in force, the Act creates a single, clear legalization procedure, introducing, at the same time, unknown construction law, simplified procedure for legalization the so-called old illegal constructions. Legalization is still a phenomenon negatively assessed by the legislature, combined with the obligation to pay the legalization fee. The Act lacks solutions improving the detection of illegal constructions and the execution of demolition orders. Justified juridical doubts, in the aspect of compliance with the principle of equality before the law, are also caused by the formulation of provisions devoted to the legalization of illegal constructions, in which 20 years have passed at least since the construction was completed.