This report presents a proposal for an internationally coordinated standard ensuring an effective taxation of ultra-high-net-worth individuals. In the baseline proposal, individuals with more than $1 billion in wealth would be required to pay a minimum amount of tax annually, equal to 2% of their wealth. This standard could be flexibly implemented by participating countries through a variety of domestic instruments, including a presumptive income tax, an income tax on a broad notion of income, or a wealth tax.
The report presents evidence that contemporary tax systems fail to tax ultra-high-net-worth individuals effectively, clarifies the case for international coordination to address this issue, analyzes implementation challenges, and provides revenue estimations. The main conclusions are that (i) building on recent progress in international tax cooperation, such a common standard has become technically feasible; (ii) it could be enforced successfully even if all countries did not adopt it, by strengthening current exit taxes and implementing “tax collector of last resort” mechanisms as in the coordinated minimum tax on multinational companies; (iii) a minimum tax on billionaires equal to 2% of their wealth would raise $200-$250 billion per year globally from about 3,000 taxpayers; extending the tax to centimillionaires would add $100-$140 billion; (iv) this international standard would effectively address regressive features of contemporary tax systems at the top of the wealth distribution; (v) it would not substitute for, but support domestic progressive tax policies, by improving transparency about top-end wealth, reducing incentives to engage in tax avoidance, and preventing a race to the bottom; (vi) its economic impact must be assessed in light of the observed pre-tax rate of return to wealth for ultra-high-net-worth individuals which has been 7.5% on average per year (net of inflation) over the last four decades, and of the current effective tax rate of billionaires, equivalent to 0.3% of their wealth.