Pretty sure a tax like that at the federal level would be unconstitutional. The 16th amendment authorizes an income tax, not a real estate tax on empty houses. State and local level attempts to do that would be a prieoners dilemma situation. Good for everyone overall if everybody cooperated, but too much incentive to be the one county or state that doesn’t tax the shit out of rich people for their third home, thus attracting the wealthy there.

Again I agree in principle but idk if tax is a feasible solution. (I’m a cpa btw for whatever that’s worth.)