Generally, you can claim home office deductions if you use the place regularly and use the place exclusively as your principal place of business or to meet or deal with customers, clients or patients during the normal course of business.
New case: An attorney used the first floor of his house for his law practice before moving to an apartment. He then claimed deductions for a “computer room” and a “sun room” in the apartment. Result: The attorney was allowed a deduction for the first floor space because it was physically separated from the rest of the house, with a separate entrance and awning. But he did not provide sufficient proof to qualify for deductions for the two apartment rooms.