Interesting that they don't mention Vancouver, who also implemented a vacant-housing tax last year.
In Paris, they need to come up with a "market rent" figure for each and every property to tax. Do they have those numbers? Using assessment value as Vancouver does, seems a lot easier.
Also, I wonder what's a bigger number: 1% of assessed value, or 60% of market rent. The previous 20% of market rent seems to be a low number, compared to the wealth stored in the property.
The problem with Vancouver's system is they determine vacancies through a survey. If you lie, you pay a severe penalty. However, they have a track record of not enforcing anything.
For example, the city has a law preventing the use of a home for an AirBnB full-time without a B&B license. Only 56 B&B licenses have issued in the metro area, and there were more than 2,570 listings that violated that rule at last check. City's response to our article was they have no idea how to figure that out...we offered the bot that cross references it and they said no thanks.