The mortgage interest income tax deduction allows taxpayers, including married couples, to write off the interest paid on mortgages on the first home and a second home as long as the second home meets the qualifications.
A second home can qualify if the home is not rented out or, if the home is rented out, if the married couple uses it for the greater of 14 days or 10 percent of the time it is rented out. For example, if the house is rented 60 days of the year, the couple would have to use the home at least 14 days.
The limit on the amount that can be deducted equals the interest on the first $1.1 million of combined mortgage debt on the two homes. For example, if you had a $500,000 mortgage and a $340,000 mortgage, the entire amount would be deductible.
To claim the mortgage interest deduction, you must itemize. You cannot claim the mortgage interest deduction if you claim the standard deduction.