How do they verify that it's empty? Is there some national registry of people's declared residence, and if that property is not occupied by someone's primary residence, it gets taxed at this penalty rate?
Could also obtain water usage data from the city water dept. Fairly reliable indicator of occupancy, although you’d need to ensure someone wasn’t running the taps needlessly to avoid the tax.
In the U.S. the IRS determines your "primary address" based on where you physically spend the most time [0]. I'm sure Canada has similar rules for tax purposes and cities could get this info from local and national tax returns.
IMO, it makes more sense just to have a high property tax rate and return funds to residents (either directly, or through well-funded city services). It achieves basically the same thing in the end, but with less fiddling over details like verifying emptiness.
