I:8-44 Qualified Residence Interest. During the current year, Tina purchases a beachfront condominium for $600,000, paying $150,000 down and taking out a $450,000 mortgage, secured by the property. At the time of the purchase, the outstanding mortgage on her principal residence is $700,000. This debt is secured by the residence. The FMV of the principal residence is $950,000. She purchased the principal residence in 2018. What is the amount of qualified indebtedness on which Tina may deduct the interest payments?