As long as you own the house you can deduct the mortgage interest on schedule A. It doesn't matter who is living in the house. However, if your standard deduction exceeds the Schedule A calculation then the mortgage interest doesn't matter.
You are allowed to deduct mortgage interest as part of your Schedule A Itemized Deductions for your main home plus one additional home. Both homes do not have to be occupied in order to deduct the mortgage interest.
If the property in question is a rental property that has been placed in service, then the mortgage interest would be deducted as part of Schedule E Rental Income and Expenses.
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