You also have additional deductions on expenses that you don't get on a single owner-occupied home. In fact it goes in a different Schedule than personal. One

You also have additional deductions on expenses that you don't get on a single owner-occupied home. In fact it goes in a different Schedule than personal. One chooses a percentage of personal and business, which might be 50 50 if each unit is about the same and the owner is in one, while the other rented out.