The subject of this article has been the object of repeated administrative and judicial discussions, given the difficulty of delimiting the limits and identifying the characteristics between tax avoidance, tax evasion and tax planning. It should be noted, therefore, that the central discussion of the topic is exactly how the definition of tax avoidance and tax evasion and its limits, since they are not unanimous by the doctrine. This lack of definition is so serious that it undermines the very determination of a standard (fixed, and safe) criterion to distinguish fraud from fiscal elision, since, at least in theory, since the taxpayer legitimately removes the tax obligation, his conduct must be respected by the Treasury, which can not punish him. Thus, the hypothesis is initially raised that the only safe criterion currently - but not yet completely, given its exceptions - to distinguish and identify whether the acts practiced deal with tax evasion or avoidance, is to verify if the acts to avoid, delaying or diminishing the payment of the tax were practiced before or after the occurrence of the taxable event. As a secondary hypothesis, the idea is that the anti-circumvention and anti-evasive norm itself causes confusion in the distinction between concepts, since it imposes taxation at all costs, preventing free tax planning. Thus, the brief study seeks to know and understand these limits based on the latest jurisprudence and opinions of established jurists in the tax sphere, without neglecting to observe the already established concepts of Tax Law, which will be taken as a basis to indicate which would be the most appropriate tax strategic decisions to aid in the success of a company - or put it at risk. In addition, this article aims to analyze the limits of tax planning, especially its forms, tax evasion and tax avoidance, as well as criticizing the anti-tax rule, set forth in article 116, sole paragraph of the National Tax Code.