This paper argues, by estimating a general equilibrium model and a long-term analysis, that Mexico and the United States are far from the prohibitive range of the Laffer curves for both the tax on labor and that on capital. However, analyzing the variations of these two taxes jointly in terms of the Laffer hill, the analogue of the Laffer curve in more than two dimensions, it can be concluded that both countries could raise more revenue in the long run by reducing the tax on capital and increasing the tax on labor than by raising both.