I entered 14,078 as my mortgage interest (where it was first asked under home office). My schedule A from turbotax, line 8, shows this as 23,276. In case it helps, my home office is 10% of my home's space, and was in use 9 months of the year. I rented my home out for 3 months, and so I thought that 25% of the home interest would be assigned to the home rental forms.