Commercial law, while adhering to the principle of sanctity of contracts (pacta sunt servanda), has consistently sought solutions for managing contract breaches to facilitate commercial relationships and reduce disputes. One such solution is the 'Nachfrist' provision (additional grace period) in the Convention on International Sale of Goods (CISG), which provides the possibility of granting an additional period for contract performance. This theoretical research, conducted through a descriptive-analytical method and utilizing library resources, compares the Nachfrist provision in the CISG and the laws of England, France, and Iran. In the CISG, Nachfrist serves as both an instrument for specific performance (execution of the original obligation) and a prerequisite for termination, obligating the obligee to observe a reasonable grace period and refrain from inconsistent remedies. In French and English law, termination is primarily limited to fundamental breach (material breach), with Nachfrist holding different positions; in French law, it does not affect the termination clause, while in English law, it can transform time into an essential term (condition). In Iranian law, despite the priority of specific performance (asl-e-ejra-ye-taahod), the absence of specific regulations regarding additional time has led to inconsistent judicial practice. This research, emphasizing the functions of Nachfrist in facilitating commercial relationships, reducing disputes, and enhancing legal certainty, examines Iran's legal gaps and provides practical recommendations regarding the implementation of a legal framework for additional time.