This paper analyzes the problems related to the rules that should be applied during the assessment of the evidence presented at the Judicial Tax Court when those means of proof where not accepted by the Administrative Tax Court in a decision submitted under the Articles 141° and 148° of the Peruvian Tax Code. For that purpose, we investigate the relevance of the rules provided by Articles 141° and 148° of the Peruvian Tax Code, which contribute to give legitimacy and effectiveness to the collaboration duty that taxpayers must accomplish during the tax audits conducted by the Peruvian Tax Administration, which constitutes the basis of the tax controversy discussed whereas at the administrative level or at the judicial process. Furthermore, we raise awareness of the characteristics that are inherent to the Contentious - Administrative Process, governed by Law N° 27184, in order to dis...