The injured party's obligation to reduce damages, which is an accepted rule in common law law, is a defense that is expressed by the defendant in a liability lawsuit. The meaning of this rule is that the victim of a breach of contract or another harmful act has the duty to conventionally prevent the occurrence of the loss or reduce its scope. If the defendant can prove his negligence, he will be exempted from paying damages for that part of the loss that was avoidable. The question is whether this legal entity, which is also reflected in international documents, can be applied in Iranian law or not? The analysis of this institution shows that its implementation in our laws is obvious and easy on the one hand, and on the other hand, considering its main scope, i.e. contracts, prevents it. In this article, an attempt has been made to show the concept and theoretical foundations of this rule that the non-claimability of compensable losses is related to the customary inability to attribute and indirectness of this part of the loss, which is fully accepted in our laws. The main channel for the implementation of the said rule is in private law. But the question is whether it is possible to implement the rule in administrative contracts where the government is one side of the relationship? The research method in this study is descriptive-analytical, and library sources were used to collect the sources.