Simpler calculation for 2015 home office deduction In the past people who worked at home often didn't take the home office-deduction on their income return. They thought the rules were too complex or worried that taking it would be an invitation to get audited. Now, there's a simple calculation you can use. Multiply the square feet of the home used for your office, up to 300 square feet. You can claim $5 a square foot, not to exceed $1,500.