Millionaire Concentration Misleads Tax Policy

Policymakers and researchers often treat the existing concentration of high‑income filers as evidence that a jurisdiction’s tax regime ‘works’ for the rich, but concentration is not the same as causal policy effect; short snapshots, selective state definitions, and mismatched marginal‑rate comparisons can produce misleading claims about who will move when taxes rise. Robust policy decisions require temporal tracking, consistent tax‑progressivity measures, and attention to networked migration drivers (housing, amenities, prior flows) rather than relying on one‑year concentration statistics. — If accepted, the flawed inference that progressive rates do not deter wealthy in‑migration can materially change state budget politics and push lawmakers toward higher top rates with an underestimated migration risk.