Within the field of didactics of second language teaching, it is believed that phonic errors cannot be completely corrected due to the significant influence of L1. However, improving the processes of acquisition of an L2 implies learning pronunciation properly. Given the importance of pronunciation for communication, it is necessary to deeply know the nature of phonic errors, which requires a specific classification aimed to describe, classify and categorize them. This article is intended to test the validity and efficiency of the taxonomy developed in the project AACFELE. To accomplish our objective we: a) collected the most significant phonic errors made by learners of Spanish from nine different nationalities and b) categorized those errors. As a result, we found that the classification entails plenty of trouble caused by the impossibility of marking the boundaries of the numerous phenomena involved in the pronunciation of a sound; that is why we considered the need of redefining some of the suggested categories and assessed the adequacy of maintaining other ones less useful. Despite these circumstances, the most significant outcome was the reliable proof that the taxonomy AACFELE allowed us to label and describe diverse phonic errors using common criteria, which represents the first step to accurately study phonic acquisition of a foreign language.