This article examines the grounds and limits of contractual qualification of obligations subject to personal performance. It examines the relationship between the general rule regarding the possibility of performance by a third party and the norms of civil law that establish or permit personal performance. Particular attention is paid to the distinction between the personal nature of performance, which arises from the law, the essence of the obligation, and the agreement of the parties. The legal consequences of engaging third parties contrary to the terms of the contract or the essence of the obligation are analyzed. It substantiates the conclusion that the condition of personal performance cannot be considered in isolation from the actual content of the relationship and cannot be used to replace labor relations with a civil law construct.