Code JEL : H21, H23, F13, F18In this paper, we address two questions: (i) how should a government pursuing both environmental and redistributive objectives design domestic taxes when redistribution is costly, and (ii) how does trade liberalization affect this optimal tax system, and modify the economy's levels of pollution and inequalities ? Using a general equilibrium model under asymmetric information with two goods, two factors (skilled and unskilled labor) and pollution, we fully characterize the optimal mixed tax system (nonlinear income tax and linear commodity and production taxes/subsidies). We also provide simulations highlighting the linkages between pollution, labor income redistribution and increasing globalization with our endo...