In this paper we employ a tax-competition model to demonstrate that in the presence of migration the re-distributive advantage of a non-linear income tax system over a linear (flat) one is significantly mitigated relative to the autarky (no-migration) equilibrium. When migration threats are sufficiently strong, a coordinated shift from a non-linear (prima-facie superior) system to a flat (inferior) regime is not too welfarecostly, even when the extent of re-distribution is significant. Therefore, such a shift may be warranted on administrative grounds. We also show, as expected, that migration reduces the extent of redistribution.