It has also not proved the opposite. The feared collapse has not appeared. The state did not watch the surtax base vanish. The available migration data do not show a clean millionaire exodus caused by the tax. And the revenue has been too large to dismiss as a political mirage.
The lesson is not that taxes have no consequences. The lesson is that consequences have to be measured, not assumed.
For a national tax, the lesson is sharper. If the goal is to tax very high income, a federal surtax is more enforceable than a wealth tax and less vulnerable to interstate migration than a state surtax. But it would still leave the largest structural problem in the tax code: the ability of very wealthy people to choose when, whether, and how their gains become taxable income.
That is why the real policy choice may not be between doing nothing and imposing a pure wealth tax. A more durable approach would combine a national high-income surtax with stronger rules on capital gains, trusts, pass-through entities, stepped-up basis at death, and IRS enforcement.
The fight would not end. It would move.
At the state level, the symbol of avoidance is the moving van headed south.
At the national level, it is the tax lawyer at the conference table.
And that may be the real lesson from Massachusetts. The millionaire’s tax did not end the argument about taxing the rich. It clarified it. The question is no longer whether government can raise money from million-dollar income. Massachusetts has shown that it can. The question is whether the tax system can follow wealth when wealth stops looking like income.
Bibliography
1. Massachusetts Taxpayers Foundation, “FY 2026 Consensus Tax Revenue Agreement,” Jan. 10, 2025.
2. Pioneer Institute, “Tax Flight Takes Off: IRS Data Reveal Surge of Massachusetts Residents Fleeing to Tax-Friendly States Following the 4 Percent Surtax,” Mar. 19, 2026.
3. MassBudget, “New IRS Migration Data Shows No Evidence of Surtax-Driven Outmigration, Highlights Affordability Challenges,” Mar. 19, 2026.
4. Internal Revenue Service, Statistics of Income Migration Data, filing years through 2023.
5. Cristobal Young et al., research on millionaire migration and state taxation.