IRS Form 8829 is used to calculate business use of the home expenses that can be claimed on your tax return. Â The form looks at direct and indirect expenses and most expenses are taken on a pro-rata basis. Â The video below has been prepared by tax attorney John McGuire to provide additional information regarding IRS Form 8829. Â If you have tax related questions or issues, you can contact The McGuire Law Firm to speak with a tax attorney in Denver, Colorado or Golden, Colorado.