A second home you don’t rent to anyone qualifies for the home mortgage interest deduction. Rental property, on the other hand, doesn’t. Whether a second home you rent out for only part of the year will or won’t be considered “rental property” depends on how many days you rent it out. If you use your second home for less than 14 days a year or less than 10% of the days you rented it, it is considered rental property and will not qualify for the home mortgage interest deduction.