Optimal marginal and average income taxation under maximin

Using the Mirrlees optimal income tax model under maximin, we derive fairly mild conditions for a decreasing marginal tax rate throughout the skill distribution with no bunching, a strictly concave tax function in income and a single-peaked average tax schedule. Assuming additive preferences and an isoelastic disutility of labor function, these tax profiles are implied by aggregate skills that are non-decreasing with the skill level. If preferences are quasilinear in leisure or in consumption, these tax profiles are also obtained under a large set of skill distributions.