International audience In a model where agents have unequal skills and heterogeneous preferences about consumption goods and leisure, this paper studies how to combine commodity taxes and non-linear income tax. It proposes a particular social welfare function on the basis of fairness principles. It then derives a simple criterion for evaluating the social welfare consequences of various tax schedules. Under the proposed approach, the optimal tax should have no commodity tax for some range of consumptions, and income redistribution would feature high subsidies to the working poor. It is also shown that, even when the income tax fails to be optimal, commodity taxes may not improve social welfare.