The purpose of the article is to analyze the issue of applying Article 115 of the Polish Civil Code to the calculation of the limitation period. The subject of the considerations is to determine whether the limitation period may be regarded as a “time limit for performing an act” within the meaning of Article 115 of the Civil Code, and what legal consequences arise from adopting a different classification. In this respect, the article examines the current positions of legal doctrine and the case law of the Supreme Court. As a result of the analysis, it is indicated that the lapse of the limitation period ex lege gives rise to the debtor’s competence to raise the defence of limitation, regardless of statutory non-working days. The novelty of the article lies in the comprehensive comparison and systematization of doctrinal views and judicial decisions in the light of the amendment to Article 118 of the Civil Code, thereby contributing to a more in-depth understanding of the function of limitation periods in the Polish civil law system.