Atkinson and Stiglitz show that with weakly separability, differential commodity taxes are unnecessary given an optimal nonlinear income tax. Deaton showed that with an optimal linear progressive income tax, commodity taxes are superfluous under weakly separable and linear Engel curves. Using...

The traditional normative literature on fiscal federalism argues that redistributive policies should be centralized in order to avoid welfare- or tax-induced migration. However, recent evidence shows that even in a setup where the progressivity of the income tax schedule is centralized to an...