So what would the unintended consequences be for changing property tax to be a percentage of the actual annual rent for leased or pay-to-stay properties, assume

So what would the unintended consequences be for changing property tax to be a percentage of the actual annual rent for leased or pay-to-stay properties, assume a statutory minimum rent for vacant properties, and stay with assessed valuation times mill rate for owner-occupied properties? The property tax assessed in this way would be deducted from income, to avoid double-taxation. The desire to minimize the cost of owning a property should create an incentive to ensure a residence is occupied by at least one person who can pay, so the statutory minimum would probably be set such that renting at below-market rates would be slightly less costly after taxes and insurance than the tax rate for a vacancy.