IRS Form 8829 is used by taxpayers to calculate the allowable expenses for business use of your home. This is a copy of the form provided by Council Member Pat Berryman in response to The Austin Bulldog’s Open Records Request to support the amount she claims as an expense for a home office. Line 1 indicates a home office of 495 square feet. Line 35 indicates an allowable expense of $6,644 for 2009. That amount divided by 12 and rounded to the nearest dollar would equate to an allowable monthly expense of $544 for a home office.