Generally, the key to whether you an interest expense is deductible for income tax purposes is if the funds were borrowed to provide the capital used to earn income. For example, mortgage interest on your home is not tax deductible but if a portion of the home is used to earn rental income, a corresponding portion of the mortgage interest paid is deductible.

Tax Advisor > Claiming Deductions > Itemized Deduction for Interest Expenses ... Am I required to have my ex-wife sign off on the home loan interest to