A função extrafiscal do IOF: análise da extrafiscalidade e o impacto na segurança jurídica

Abstract

This paper analyzes the extrafiscal function of the Tax on Financial Operations (IOF) in light of the principles of legal certainty, legality, and non-surprise. It adopts a deductive-bibliographic method, based on doctrine, legislation, and case law. The study examines extrafiscality in Brazilian Tax Law and the exceptional regime of the IOF, particularly its exemption from anteriority and strict legality. It argues that the use of the IOF for revenue purposes, under the guise of extrafiscal policy, constitutes a deviation of purpose and violates legal certainty, undermining the predictability of the tax system. The analysis of cases from 2021 and 2025 highlights the negative effects of this practice and reinforces the need for control over Executive measures.