摘要:As in many countries around the world, the debate about tax planning concerns its limits, and there is a clash between two perspectives on the subject. On the one hand, there is a traditional perspective, whose advocates argue for the need to preserve the legal security of the taxpayer and the use of a more formalist interception method of tax rules. On the other side is the contemporary perspective, which seeks to balance the need to protect the taxpayer against abuse of tax authorities, but without neglecting the fact that the taxpayer sometimes practices abusive tax planning. At the center of this debate is the Federal Supreme Court (STF), a Brazilian constitutional court, which will examine the constitutionality of the sole paragraph of Article 116 of the National Tax Code, which for some academics is considered the Brazilian GAAR. The present paper aims to introduce and analyze some landmark points of the debate in Brazil, highlighting the legal reasoning deployed in this debate and the challenges for de constitutional process.