What if the business percentage of a cost is different than the percentage of my home I used for my business?
Enter only the business portion of the expense on the Home Office Only Expenses screen. Don't enter the expense on the Expenses for the Entire Home screen.
For example, let's say you used 10% of your home for business purposes. You have an $800 electric bill that is for lighting, cooking, laundry, and television. Since cooking, laundry, and television are not part of your business, you should estimate how much of the electric bill is related to those activities since you can't deduct those costs. In this instance, say $600 is related to cooking, laundry, and television and $200 is related to lighting. You would enter $20 (10% * $200) as an expense on the Home Office Only Expenses screen.