revenue is not the same as profit
having revenue just means you are doing business. with expenses and depreciation, most rental is a lossing business. you do depreciate your property, correct? depreciation is required.
plus, rental income is passive, unless you can prove that you are a real estate professional, this is not really a "business" per se. there are requirements you have to meet in order to qualify for real estate professional. you need to at least work on the rental for like 20 hours a week or something.