The measured cost of wealth-tax flight is a few points of revenue, not a collapse.
Norway's 2021–2025 natural experiment finds migration concentrated in the top 0.1% and cutting the revenue gain from 75% to 71.5% with no founder or firm effects, while California's dueling +$100B and −$25B scores trade elasticities that — as Slemrod concedes — no enacted design has ever produced.
The same conclusion keeps arriving from across the workspace's research — 1 topics independently instantiate this theme. Filter the evidence by where it came from:
The only rigorous measurement puts flight's revenue cost at roughly 3.5 points of a 75% gain — under 5% of the expected take, with at most ~100 leavers and no firm or founder effects.
The finding deploys the measured record directly against the −$25B collapse score while Slemrod notes neither side's estimate has a true precedent — assumed elasticities on both ends, measured flight near the floor.