A monographic work carried out through bibliographical research with the aim of analysing the current effectiveness of two constitutional tax principles, namely the principle of contributory capacity and the principle of non-confiscation, in the face of the tax burden borne by Brazilian taxpayers today. After analysing the position occupied by the constitutional provisions referring to the aforementioned principles, it can be seen that both do not have the immediate effectiveness they should have. The realisation of the normative force present in the provisions studied must be promoted through the actions of the Judiciary.