The principle of non-contestation in tax proceedings is of great importance because of the compression of the preliminary investigation and the limitation of the admitted evidence. For this reason, and because of the nature of the controversial relationships, the Judge must, therefore, cautiously recognize the non-contested facts. Furthermore, it is necessary to distinguish the position of the imposter from that of the taxpayer, allowing only the latter to contest the facts that the adversary alleges during the tax investigation only in the course of the proceedings. The contestation must then take place in the first useful defence, but in the absence of preclusions, the respondent may challenge the facts submitted by the appellant in the run-up to the hearing when it appears beyond the time-limit laid down in Article 23 of Legislative Decree No 546/1992. Finally, again because of the particular importance of the matter at issue, a “late but justified” challenge is admissible, while respecting the principle of the right to be heard.