The aim of this book is to develop the theme of "entry by homologation" as an essential act in the process of positivising the law. To this end, the aim is to demonstrate the importance of the entry (an individual and concrete rule) as a link between the hypothesis and the consequence, its function of incidence between these two elements in the process of constructing the legal rule, which is essential for the constitution of the tax credit that only the administrative authority has the competence to carry out, and the modalities of the entry, how entry by homologation takes place in the deontic operation and in the event of its non-compliance, the need for ex-officio entry and the initiation of administrative proceedings in order to obtain any payment or difference or even to remedy any irregularity on the part of the taxpayer in their "declaration", as well as the violation of constitutional and legal principles if the tax authorities directly initiate tax enforcement without entry by the administrative authority.