I'm not hugely against vacancy taxes really, but they need to be well-targeted to not affect the occasional bit of bad luck or renovation. Otherwise, the only way it actually helps the market is if it causes enough previously withheld supply to enter the market, and most expensive cities don't actually have all that many vacancies. NYC is at something like 5%, which included units between tenants and those under renovation. Sure, there's the occasional billionaire with an empty penthouse, but compared to the millions of renters looking for normal housing, there really aren't that many rich oligarchs hoarding housing for fun and games.