This article, while explaining the proposal, didn't seem to think it was a good idea...
The tax foundation is a right-wing think tank. Most of the assertions in the article are bullshit. This, in particular, has no basis in sound economics:
The proposal would increase the tax burden on US savers, placing foreign savers at a
relative advantage as they would not face the minimum tax. Raising taxes on domestic savers reduces the amount of domestic saving in the economy. In turn, foreign savers would finance a greater share of investment opportunities in the US. Over the long run, American incomes would fall as investment returns flowed to foreign savers instead of American savers. It would also manifest in a shifted balance of trade, increasing the trade deficit, all else held equal.
1. The tax does not apply to "savers."
2. Generally speaking, foreign investment is a good thing for a country. FDI does not actually make domestic incomes fall. This is basic economics 101. Actually, it's not even that sophisticated. Weighing costs against benefits requires, you know, looking at both. This paragraph looks only at costs of FDI without considering the benefits that the FDI creates. It's just the standard analysis from ignoramuses who think trade deficits are a bad thing because foreigners end up holding more assets.
3. This paragraph seems completely oblivious to the single most fundamental principle of tax policy, which is that everything is a tradeoff. You have to raise money somehow. All taxes are distortionary in some way.
4. LOL at the idea that this tax would shift the balance of trade. The effect is too small to be noticeable either way.
