33. Greg Grove pays $50,000 interest in 2019 on his mortgage on his principal residence. It has an interest rate of 4 percent and balance of $1,250,000 during the year. He took out the mortgage in 2018. How much of this interest is deductible on Greg's tax return for 2019? 33. Greg Grove pays $50,000 interest in 2019 on his mortgage on his principal residence. It has an interest rate of 4 percent and balance of $1,250,000 during the year. He took out the mortgage in 2018. How much of this interest is deductible on Greg's tax return for 2019