Monotonic redistribution of non-negative allocations: A case for proportional taxation revisited

- We reconsider Casajus' (TE, forthcoming) characterization of proportional taxation.
- He characterizes taxation at a fixed rate by efficiency, symmetry, and monotonicity.
- This does not work on the restricted domain of non-negative income.
- On this domain, the tax rate may vary with total income.
- There are upper and lower bounds on the elasticity of the tax rate function.

We reconsider Casajus' (forthcoming) characterization of uniformly proportional taxation by three properties of redistribution: efficiency, symmetry, and monotonicity. When restricted to non-negative income, these properties imply proportional taxation in a weaker sense-the tax rate may vary with total income but only in an economically reasonable way.