Brazil has one of the worst distributions of income in the world. The wealth of the richest 1% of the population is equal to that of the poorest 50%. Brazil has a greater concentration of wealth than ninety-five percent of the countries on which data is available. In the legal field, tax justice is based on the constitutional principle of the “ability to pay”, according to which taxes should be paid based on the economic capacity of the taxpayer. This principle first appeared in the Brazilian legal order in the 1946 Constitution, was excluded from the texts of 1967/69, and reappeared in § 1 of article 145 of the 1988 Constitution. The aim of this paper is to examine two possible grounds for the ability to pay principle (equal sacrifices and proportional sacrifices) to show how, in Brazil, the interpretations that seek to assign a positive content to the principle are limited to the horizons of a particular form of State associated with the theory of equal sacrifice. This theory for its turn is consistent with a theory of justice, under which no expense or charge levied by the government can alter the distribution of welfare produced by the market. As the application of the ability to pay principle is done within the limits of that horizon, as a consequence, this principle does not play an important role in the issue of reduction of inequality in Brazil.