what else would someone be doing with a property that they aren't themselves living in? if you support a punitive tax on people holding out for higher rent, you probably don't care if it also hits people who are merely speculating on real estate.
- Maybe they haven't found a suitable tenant yet.
- Maybe they are holding it open for a friend or family member.
- Maybe they want to do some renovations before renting it out.
- Maybe they want to sell the property and it's easier to sell without an existing tenant.
I can think of lots of reasons.
Then they should lease it meanwhile or pay the tax, it's rare for people to buy houses fully finished, say, a year in advance.
>- Maybe they haven't found a suitable tenant yet.
They can lower the price to find a suitable tenant faster.
>- Maybe they are holding it open for a friend or family member.
Then that friend or family can move there officially while still occupying their current dwelling until the grace period expires again.
>- Maybe they want to do some renovations before renting it out.
These laws in practice have an exemption for rénovations.
>- Maybe they want to sell the property and it's easier to sell without an existing tenant.
Then they should price it as to sell within the grace period, or pay the tax.
I'll answer my own question: the root problem of too high rents is that governments:
1) have outlawed the construction of enough new housing to meet demand.
2) many places (CA especially) have property taxes that are drastically too low (and in CA's case, radically unfair).
Vacancy taxes are a bad hack. As you note in your comment you have to build in all kinds of grace periods or exceptions and even these can often be easily gamed or ignored.
Cities will be much better off if they fix the real underlying problems.
>What's so special about housing that you need an extra special tax like this? We don't have it for cars or machinery or other kinds of capital goods.
Land is not capital. It is not infinitely reproducible. You can't make more land, and as a result there is hard limit to any one kind of housing.
>1) have outlawed the construction of enough new housing to meet demand.
I agree that this should be fixed
>2) in many places (CA especially) have property taxes that are drastically too low (and in CA's case, radically unfair).
That is really far from being the reason for high rents, since most places with high rents don't have Prop 13.
An unused plot of land sitting fenced off in the middle of your city extends everyone's commute and diminishes the services available within walking distance in its neighbourhood. A municipal government interested in a functioning city will want to put that space to better use just like the factory owner did, and structure landowner incentives appropriately.
A tax helps encourage owners to minimize those negatives and could easily be phased in or have an appeal process (e.g. show that you have building permits for a 6 month waiver).