What mortgage interest is deductible for the home office deduction?
Enter the entire amount of mortgage interest and points in both the Home Office section and the Form 1098 area of the Itemized Deductions section. Using the square footage amounts you entered on the previous screen, we'll calculate how much can be deducted as home office expenses. The rest will be included with your Itemized Deductions.
For example, suppose you have $10,000 of mortgage interest and the home office percentage of your home is 10%. You would enter the entire $10,000 on the Expenses for the Entire Home screen and in the Itemized Deductions section. $1,000 ($10,000 X .10) of the mortgage interest will be deducted as home office expenses, and $9,000 will be included in your Itemized Deductions.
If you decide to use the simplified method to report home office expenses, just enter the entire amount of mortgage interest in the Form 1098 area of the Itemized Deductions section.