New cross-border info sharing makes evasion impossible.
Saez ’19 [Emmanuel and Gabriel Zucman; September 5; Chancellor’s Professorship of Tax Policy and Public Finance and Directs the Center for Equitable Growth at the University of California, Berkeley; Assistant Professor of Economics at the University of California, Berkeley; Brookings Institution, “Progressive Wealth Taxation,” https://www.brookings.edu/wp-content/uploads/2020/10/Saez-Zuchman-final-draft.pdf]
A modern wealth tax can overcome these three weaknesses. First, offshore tax evasion can be fought more effectively today than in the past, thanks to a recent breakthrough in cross-border information exchange, and wealth taxes could be applied to expatriates (for at least some years), mitigating concerns about tax competition. The United States, moreover, has a citizenship-based tax system, making it much less vulnerable than other countries to mobility threats. Second, a comprehensive wealth tax base with a high exemption threshold and no preferential treatment for any asset classes can dramatically reduce avoidance possibilities. Third, leveraging modern information technology, it is possible for tax authorities to collect data on the market value of most forms of household wealth and use this information to prepopulate wealth tax returns, reducing evasion possibilities to a minimum. We also discuss how missing market valuations could be obtained by creating markets. In brief, the specific way in which wealth was taxed in a number of European countries is not the only possible way, and it is possible to do much better today.