For utilities, you have either of two methods you can use, and you can switch methods each year if you want.
Method 1:
Based on number of people in the house. If you have 5 people and two of them are renters, then utilities are allocated to 20% per person. With two renters, 40% of your utilities are a SCH E decution.
METHOD 2:
Based on square footage that is exclusive to the renter. Assume 5 people in the house, and you are renting one bedroom to a couple. That one bedroom accounts for 10% of the total floor space that is exclusive to the renter. You can claim 10% of your utility expenses on the SCH E.
