This paper addresses one of the most controversial elements of recent urban planning law: the expiration of building permits, analyzing recent trends established by the Supreme Court, the General Comptroller’s Office and the doctrine. To this effect, it is shown that at present a more or less certain statute of this institution can be reconstructed, in spite of which there is a growing judicialization on some aspects that make it necessary to think of solutions of lege ferenda that grant greater legal certainty in the development of projects.This paper addresses one of the most controversial elements of recent urban planning law: the expiration of building permits, analyzing recent trends established by the Supreme Court, the General Comptroller’s Office and the doctrine. For this purpose, it is shown that nowadays a certain statute of this institution can be reconstructed, in spite of which there is a growing judicialization on some aspects that make it necessary to think of solutions of lege ferendathat grant greater legal certainty in the development of projects.