This paper is based on a case study of the fiscal policy changes in Brazil. In that country, the paradigm of the tax system has changed following the implementation of the 1988 Constitution and the democratization process. Notwithstanding this initial change in policy, its paradigm has developed in a way different from what the cognitive theory has prescribed: not as a radical change, but in a more progressive way. Thus, the analysis of change in a public policy based solely on the cognitive criteria has shown limitations and does not explain the process that has occurred in the case of taxation in Brazil. Additionally, approaches to historical institutionalism have proposed a much more refined model for explaining the change in public policies by presenting a model based on incremental changes. This article proposes the notion of change by “cognitive layering” and defends a vision according to which the study on the changes of public policy requires a link between the ideas and the institutions, through the combination of the cognitive approach and neo-institutionalism theories. Furthermore, this study also shows that, in the case of taxation in Brazil, cognitive changes have subsequently led to institutional changes.