Unmarried Co-Owners of Residence with > $1 Million Mortgage

Home mortgage interest is only deductible on up to $1 million of debt used to buy or improve a taxpayer’s primary residence. If two unmarried persons are co-owners of a home they both use as their primary residence, the question arises as to whether each owner has a separate $1 million limit. The IRS recently took the position (no surprise) that the $1 million limit applies per property, not per taxpayer. Therefore, the $1 million has to be split among the owners based on their percentages of ownership. IRS office of Chief Counsel Internal Legal Memorandum 200911007.