Turbo Tax is calculating my mortgage interest deduction incorrectly. Married filing jointly - so I can take mortgage deduction via itemized decution up to a loan of 750K.

I refinanced a loan of 850K. Paid interest as 23K with original mortgage and 5K with refinanced mortgage. Avg Loan amount for the year = 859K I calculated a factor of 87%. Interest allowed for deduction should be 24K, whereas Turbo tax shows 12K as deduction. It's wrong. It's treating the refinance as a second loan, I think!