The present study aims to examine, in the light of the theory of juridical fact, the phenomena of exemption and zero percent rate. To meet this goal, we seek to initially outline the essential concepts of the theory ponteana. Then we study the structure of formal logic-tax rule, identifying the criteria for their hypothesis and its consequent. Finally, based on the notes above, arrives at the conclusion that the exemption will no incidence of taxation standard, due to previous incidence of the

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... tandard exemption that becomes insufficient factual support the standard tax, hindering the emergence of tax legal fact, and in the situation of zero rate, there incompleteness of the standard tax because of the nullification quantitative criterion of its consequent, not having thus able to focus on the factual support therein.