This would be specifically to fix the problem of a builder making a bunch of apartments and slowly letting them into the market to artificially inflate home values.

Presumably, the building company would be the owners for all the empty apartments which would make it easy to find and tax. It would be more difficult to detect someone buying a home/apartment as an "investment".

> This would be specifically to fix the problem of a builder making a bunch of apartments and slowly letting them into the market to artificially inflate home values.

That isn't the reason rent is high in SF.

At what point do they become apartments though? When the Certificate of Occupancy is issued? "No problem; those units aren't finished yet. [They need a smoke alarm to be legal units and somehow we haven't found the time to get around to it yet.]" Or whatever the threshold is between "this is a vacant lot" and "this is a taxable unoccupied unit", you're just providing incentive to stay on one side of that line if there is a glut of builders using this strategy.

IDK, probably have to do some research into how much time it takes to finish a unit to say when the clock starts ticking.

For example, obviously a smoke alarm is something that takes 15 minutes to install, so that wouldn't be when you start the clock.

You might be able to base it on when any single unit is sold in the block. That is "You sell 1 apartment, you've got a year to sell to rest or you are going to start seeing vacancy taxes".

So, in Florida, you declare your primary residence, and it is taxed at a much lower rate than other property.

See ‘homestead exemption’. Other states use this term, but it means different things.

WV, for instance, only allows the exemption for people above a certain age.

Same in Indiana. But the proposed idea was to tax more heavily all unoccupied properties, not merely "all properties other than one's primary residence."