[UweSchmidt]

Having a building vacant is already incredibly expensive; costs and interest add up and the building can get severely damaged (a building has to be heated in winter, ventilated properly and issues like broken pipes have to be found quickly by tenants etc.). Common reasons for vacancies are probate disputes, owners that are house rich but cash poor and can't handle maintenance, issues with building code and permits and similar. Apart from some truly dysfunct situations a scheme that involves vacancy doesn't make much sense. Why not take even a modest rent for a bit?

In general, everything you could propose that puts pressure on landlords leads to transfer of ownership from your (maybe friendly) landlord with 2-3 units, to larger, more professional companies who can handle the paperwork and regulations, with a tendency to tear down and rebuild something that is more expensive to rent or buy.

[terminalcommand]

In countries with high inflation purchasing real-estate and keeping it vacant is an inflation hedge. Plus, you also benefit from low interest rates and get free money if your government allows it.

I live in Turkey. We had 80% p.a. inflation, where the government decided to lower the interest rates even further. Our president said Interest rates are the cause of inflation and if we lowered interest rates inflation would go down. State banks gave out house loans with 12% p.a. interest where the inflation rate was above 80% p.a.

A lot of Turkish people got their free money from the bank and invested in real estate. In Turkey, everyone evades tax and property taxes are not really collected. This in turn fueled inflation even more, sky-rocketed inequality and caused the worst housing crisis.

That is why I am convinced that property taxes are a must.

[galangalalgol]

I live somewhere with ~3% property taxes on properties, including the one you reside in. Not so long ago mortgages were cheaper than that, and mortgages at least end someday. At the same time, short term rentals like airbnb are illegal. Combined, this leads to most landlords either being companies large enough to keep extremely high occupancy rates, or families that flout the law to rent a second property owned due to marriage or inheritance and become vulnerable the whims of neighbors.

I think allowing short term rentals, and giving owners strong eviction rights for damage, illegal activity or non-payment (which we have) need to be paired with property taxes to prevent all landlords becoming large inhuman entities.

It should also be noted that if you tax everything at the value it could make, you distort the usage of valuable locations to exclude housing.