Unique EU circumstances don’t apply- multiple solutions to US defection

(Emmanuel, E. Morris Cox Professor of Economics and Director of the Center for Equitable Growth at the University of California, Berkeley and Gabriel, Assistant Professor of Economics at the University of California, Berkeley https://www.bostonreview.net/forum_response/emmanuel-saez-gabriel-zucman-final-response/ , 4-8)

The main reason why a number of European countries abolished their wealth tax is that they gave up on attempting to address international tax competition. There’s no EU-wide wealth tax, and EU member states don’t tax expatriates. A wealthy Swedish resident could avoid the Swedish wealth tax by relocating to Switzerland—it was child’s play. The international mobility of wealthy individuals would not be a concern for a U.S. wealth tax, because U.S. citizens are taxable in the United States no matter where they live. Karl Smith and Dean Baker worry that wealthy Americans would renounce citizenship should a wealth tax be implemented. But this risk can be avoided. A steep exit tax could be applied at the time of citizenship renunciation; the Warren wealth tax, for example, includes a 40 percent exit tax on net wealth. Other mechanisms could be considered. For instance, the United States could continue taxing billionaires even after they renounce U.S. citizenship. To a large extent, all large fortunes are social creations: U.S. billionaires have benefitted from U.S. markets, U.S. workers, the U.S. legal system, U.S. public infrastructure, and so on. It would be legitimate for the United States to keep taxing billionaires who built their wealth while living in the United States, even after they’ve renounced U.S. citizenship.