The article discusses the regulation of the provision of Art. 2031 § 2 of the K.p.c. [CCP], establishing time limits in raising a set-off defence in a civil trial. The analysis focuses in particular on three issues. Understanding (definition) of the set-off defence, which is reflected in the scope of application of time limits resulting from Art. 2031 § 2 of the K.p.c. [CCP]. This provision excludes the possibility of invoking a set-off where it occurred after getting into a dispute as to the merits of the case. In addition, the article points to interpretation problems arising from the connection between the time limit for raising a defence of set-off and the defendant’s due date. The considerations made finally allow for the submission of proposals for the interpretation of Art. 2031 § 2 of the K.p.c. [CCP] and making de lege ferenda postulates.