Ratcheting taxes for unoccupied houses and apartment units. Allow a grace period of one year, to allow for flips. But after that, every home you own after the first is considered unoccupied if it is vacant for more than three months of the year. And taxes on vacant homes become increasingly expensive as you own more and more of them.

Like the first vacant house you own may be near a normal tax rate, the second makes both more expensive, the third makes all three super expensive, etc… And these tax penalties should get expensive fast. Like up to (or even over) 100% if you’re sitting on more than like five or six properties. Then take the proceeds of these higher taxes, and put them towards first time homebuyer assistance programs. I’d even go so far as to say that renting a single family home shouldn’t totally eliminate the tax, only reduce it. This would solve the three largest issues with the housing market right now.

First, it solves the “sitting on vacant houses to drive up the price of rent” problem. Actively force landlords to keep their apartments and houses full, driving down the price of rent. If the unit is occupied, the tax is lower. And again, even the most expensive landlords should only be able to feasibly own three or four extra properties before the taxes get prohibitively expensive, even after being mitigated by occupation.

Second, it solves the “buying a dozen houses and only selling one of them” problem. Corporations do this to be able to game the market and drive up prices on the few they do sell. But by making it prohibitively expensive to sit on vacant houses, you preemptively wreck any kinds of profits they would make by sitting on them.

Third, it would allow for more low interest loans for first time home buyers, and could even be used to offset the potential downpayment costs.

But of course, this will basically never be implemented, because the lawmakers are all bribed by the corporations that own thousands of vacant homes.