If you’re in business and you work out of your home, you may be able to expense part of your rent or mortgage as well as utilities for your “at-home office.” But the IRS is extremely strict about this expense. Your office or studio must be in an identifiable area in your home not used for any other purpose than creating, selling or storing your art. To calculate your studio expense, measure its space and then divide it by the total floor space in your home. The resulting percentage is then applied to your rent or mortgage. The same formula may be used for your utility and real-estate tax expenses.