It's not like the money is just sitting, liquid in a vault like Scrooge McDuck.
Idea: tax loans taken out using assets as collateral at regular income tax rates. After all, that money gets used like regular income (living expenses).
The taxed amount can then be added to the basis when the asset is sold. It would be like reverse of depreciation calculations.
Set an asset and loan value floor so it only affects people with assets $10M+.
After all, regular people pay taxes on annuities, which are similar in structure.
Disclaimer: IANA-Accountant, but I am a taxpayer who tries to legally minimize my taxes.
I don’t think it’s as simple as this. This will end up catching normal people (any mortgage, automotive loan, etc) but may result in tricky accounting/loan structuring to avoid having literal collateral for the billionaires you’re trying to hit.
I don’t think that taxing unrealized gains is the solution either, but I also don’t think doing nothing is the solution. This is a very tricky problem without an obvious solution (and it doesn’t help that the ultra-wealthy can fairly easily influence lawmakers).
So just have it kick in above $5M/year or something like that, and have it only apply to securities as assets. Not a lot of ordinary people are taking $5M+/year in loans against their stocks.