You will need to enter the rental mortgage interest under the rental property.
1. Go to Rental Properties and Royalties (Sch E).
2. Answer Yes to review Income from Rentals or Royalty property you own.
3. Answer the question about time spent as Real Estate professional.
4. On the Rental Property Summary, edit your property.
5. Choose Expenses. Select I'll choose what I work on.
6. You may find other expenses on this next page, Continue.
7. The next page is where you report the Mortgage Interest.