In at least one US State, your property taxes are different if you're living in the home vs. renting it out. In my case, losing the homeowner's exemption would almost double my property taxes.

I'm not sure if you get to deduct property taxes for non-homestead property on your federal return either. In my case, losing this deduction would force me to use the standard deduction instead of itemizing. So, a possible double-whammy.

edit: note this is for the US.