Time-bar clauses are provisions in some international investment agreements (IIAs) that establish a maximum period for investors to bring their claims through international arbitration. As a general rule, this time limit starts to run from the early stages of the dispute, so if it is not taken into account in a timely manner, it may expire closing the door to arbitration. This becomes even more complex considering that these provisions have generated interpretative discussions which in turn have resulted in varied application criteria, which also impact on the computation of the time limit. In view of this scenario, this article emphasizes the importance of taking these clauses into account before the commencement of an investment arbitration and seeks to determine their scope based on the way they have been interpreted by arbitral tribunals.