Just because you own the house doesn't mean you get to write off the mortgage interest. Even if you itemize deductions -- a necessity for taking the write-off -- you may be unable to include mortgage interest. It depends on whether your mortgage meets IRS qualifications for the deduction, and who actually pays the lender each month.
If your mortgage doesn't pass the IRS tests, nobody gets to write it off. The debt has to be secured by your house, so the bank can take the property if you default. It has to be your main home or your second home. If you have some seriously expensive real estate, you can only write off interest on the first $1 million of the mortgage. That figure covers the total debt on your first and second home combined -- it's not $1 million per house.
If your name is on the title and you're also paying the mortgage, there's no problem claiming the deduction. It's when someone else makes the payment that things get complicated. If your spouse or partner takes care of the payments, for instance, she's the one who can claim the interest, even if you took out the mortgage. When you both pay part of the mortgage each month, you can each claim part of the deduction.
Generally, the IRS only allows someone to write off mortgage interest if he's personally liable for the loan. The IRS makes exceptions, however, for "legal or equitable owners." If, say, your partner lives with you, helps pay the bills, and contributes to the mortgage, that might qualify her to take the deduction, though tax courts judge such things on a case-by-case basis. If your mother pays the mortgage as a gift but doesn't live there, neither you nor she can claim the mortgage interest.
Claiming the Write-Off
If you took out the mortgage, you're the one who gets the 1098 form from the lender stating how much interest you've paid each year. If your partner claims the deduction, the IRS may wonder why someone besides you thinks they're entitled to it. Attach an explanation to your tax forms when you submit them. If one of you would benefit more from the deductions at tax time, consider having that one take over the mortgage payments so she can claim the interest.
A graduate of Oberlin College, Fraser Sherman began writing in 1981. Since then he's researched and written newspaper and magazine stories on city government, court cases, business, real estate and finance, the uses of new technologies and film history. Sherman has worked for more than a decade as a newspaper reporter, and his magazine articles have been published in "Newsweek," "Air & Space," "Backpacker" and "Boys' Life." Sherman is also the author of three film reference books, with a fourth currently under way.