[delazeur]

I think "occupancy" is pretty much a solved problem for purposes of taxation. In the U.S., for example, there are settled rules about which state gets your income taxes if you live or work in multiple states.

A simple solution to the problem at hand would be to let everyone designate any one residence as their primary residence taxed at a lower rate, with any additional property they own being taxed at a higher "secondary/unoccupied residence" rate unless they can prove it is being rented out.

[cperciva]

Residency is a solved problem for income taxes. But that's a completely different issue from occupying a particular residence; for example, an international student may for tax purposes be a resident of his country of nationality despite not setting foot in it all year.