The present contribution deals with the organizational behavior within the scope of tax planning, emphasizing especially the management options in view of the instruments made available to companies by the legislator, both at national and international levels. Thus, we emphasize the study of tax planning as a management tool, that is, as a perfectly legitimate means; and not as a tool of abuse or even tax evasion. Throughout the preparation of our work we verified that the Portuguese tax system encourages/potentiates some tax planning practices, when used with legitimate purposes, or if the legislator did not grant deductions to the tax collection, exemptions and tax benefits, for example.The major contribution of our work in academic, scientific and practical terms is a careful analysis of the state of the art in the doctrine, accompanied by an in-depth study of the various tax codes, so that, fundamentally, managers may be provided with valid information that enables the best management options regarding tax planning intra legem.