How to File a Mortgage Deduction for Nonmarried Couples

If you and another person are liable for the mortgage payments for the home that you both use as your main residence, you can split the deduction even though you aren't married. Each person claims the amount of interest that he or she was responsible for paying during the year. You don't have to file a joint return to share the deduction, but the Internal Revenue Service makes you go through a few extra reporting requirements to make sure that all the interest is properly accounted for on the tax returns.

Report the interest paid by the person who receives the Form 1098 on line 10 of Schedule A. For example, assume you and another person share the mortgage equally and you are the payer of record who gets the Form 1098. If the Form 1098 shows $9,000 in mortgage interest in box 1, report $4,500 on line 10 of your Schedule A.

Report the interest paid by the person who does not receive the Form 1098 on line 11 of that person's Schedule A. Also, write "see attached" next to line 11. For example, if you were not named on the Form 1098 but you were responsible for paying $4,500 of the $9,000 of mortgage interest for the year, report $4,500 on line 11 of your Schedule A.

Attach a statement to the return of the person who does not receive the Form 1098 explaining that another person received the Form 1098. This statement must also include the name and address of the person who received the Form 1098 as well as the amount of interest each person paid.

Add your mortgage interest deduction from line 10, if you received the Form 1098, or line 11, if the other person received the Form 1098, to your other deductions. The total goes on line 29 of Schedule A and line 40 of Form 1040.