[This testimony was delivered on December 8, 2021, to the House Committee on Ways and Means, Subcommittee on Oversight, as part of a hearing on "The Pandora Papers and Hidden Wealth."]The US is the world’s leading investment destination for offshore wealth. Our laws enable foreigners—through offshore intermediaries—to invest anonymously in the US and to grow their wealth tax-free. We are, in this respect, the world’s ultimate tax haven.The Pandora Papers spotlight Panama, source of 2 million documents in that leak. But most offshore wealth booked in Panama won’t stay there. According to the IMF, 51 percent of outbound portfolio investment from Panama pours into the US. We’re also the number-one destination for portfolio investment from other offshore financial centers, including the Cayman Islands, Ireland, Jersey, Luxembourg, and Switzerland. The US never deliberately decided to become the world’s ultimate tax haven. But whether we continue to play this part is very much within Congress’s control. Lawmakers can either acquiesce to our tax-haven status or catalyze change ....First, we either need to apply our withholding tax to buybacks or push U.S. corporations back to dividends. It is the shift from dividends to buybacks—combined with the exemption of buyback gains from withholding tax—that allows foreign nationals to invest tax-free in U.S. equities. The excise tax on buybacks in the Build Back Better Act is a modest first step in the right direction. Second, we ought to reconsider the withholding tax exemption for portfolio interest. Especially if interest rates rise in the coming years, the revenue costs of this exemption will mount. Third, we need to work multilaterally with other countries that are home to strong and stable capital markets: especially Japan, the UK and EU, Canada, South Korea, and Australia. If these countries all agree to impose comprehensive withholding taxes, offshore wealth holders who want to earn reliable returns will no longer have the option to evade tax entirely. By contrast, trying to shut down every offshore intermediary will be a game of whack-a-mole, because dozens of countries can play the intermediary role