EN
This study is devoted to the analysis of the legal basis, the premises and the content of mutual claims of co-owners for reimbursement of expenses associated with common property, as it is regulated in Polish law. The author presents the view according to which in Polish law the above mentioned obligation of co-owner is a special case of the general duty to reverse unjust enrichment, based on Article 405 of the Polish Civil Code. This view makes it possible to justify widely shared assumption according to which only these expenses associated with common property should be compensated for which are beneficial to all co-owners. The author also argues that on the basis of the statutory regulations concerning unjust enrichment it is reasonable to differentiate between the claim for reimbursement of necessary expenses associated with common property and the claim for compensation of improvements made by co-owner.