The Brazilian government offers over one million slots per year in free public universities. Nevertheless, higher education in Brazil is highly progressive. We analyze how the introduction of a tuition fee in public universities, levied upon those families that can afford it, alters the equilibrium in the higher education market. Such a tariff provides incentives for rich families to seek private education and facilitates the access of poor students to public universities. A small tuition fee generates social gains of at least R$100.000 (around five times per capita GDP) for every additional poor student that receives a public education.