[aurelienb]

We have a similar tax in Paris, France. Tips: it doesn't work (in current design). Plenty of room for improvement, either around the full renting subject (ex: lowering barriers to set up a new contract between landlord and renter, to remove some laws which overprotect some renters) or around this particular subject (decreasing time before the tax, increase tax, increase control or fine, or even more violent solution (huge fine, jail, etc)) Note that I don't know what would be the most efficient

[carlob]

I don't think the housing shortage will be fixed with tweaks to rental laws. Most of France happens in Paris (jobs, culture, …) and Paris has not kept up with the pace.

https://upload.wikimedia.org/wikipedia/commons/6/66/Croissan...

If you look at this plot you will see that the metro area has grown a lot, while the boundaries of the city haven't moved since 1860. There are various incentives in living in the city proper as opposed to one of the neighboring counties.

This is horizontal growth. Vertical growth has been forbidden for a while now as there are very tight laws about how tall new buildings can be and whether old buildings can be torn down.

Without relaxing at least one of these two constraints regulations on rent are going to do very little.

[aurelienb]

Fixed: no. But temporary improved: yes. Why: Because around 10% of Parisian flat are currently unoccupied. For a city like Paris, that's huge!

[pouetpouet]

Not really. France has a ridiculous thing called taxe d'habitation. Which means that unhabited dwellings are less taxed than inhabited ones. The tax on unhabited dwelling units in Paris can just help to recover a part of the unperceived taxe d'habitation. Canada, Germany and many other don't have such a scheme.