In this paper, we have considered the legal consequences that occur in the event that during the duration of the property insurance contract, the circumstances that were important for risk assessment during the conclusion of the insurance contract change. In that sense, we compared the relevant provisions of the Law on Obligations (ZOO), the provisions of the Preliminary Draft Civil Code of the Republic of Serbia (Preliminary Draft Civil Code of Serbia) with the solutions from comparative law and the provisions of the European Insurance Contract Law (PEICL). In comparative law, there are similarities in terms of regulating this obligation and sanctions for its violation, but there are also differences It is also important whether the insurer, if he had known about a certain fact that was not reported, would have decided to conclude the contract or not, or would have concluded it under other conditions, as well as whether the policyholder / insured was conscientious or not. The usual sanctions for breach of the obligation to report an increase in risk are the insurer’s right to choose whether to opt for termination of the contract or an offer to increase the insurance premium, or to change the contract. Complete refusal to pay the insurance fee is possible only in case of intentional-fraudulent violation of the obligation to report. The rule is that in other cases the compensation is paid in full, ie a proportional reduction of the compensation. The comparative law provides for various perclusive deadlines within which the insurer may invoke the inaccuracy of the application.