Average Mortgage Interest Calculation with Large Jan Paydown

[Mike6174]

I have a single home with a mortgage balance in Jan of $1,000,000. Paid down the loan by $300,000 in Jan with much lower principle payments the other 11 months. Turbo only lets me calculate the average balance by taking 1/1 balance plus 12/31 balance and dividing by two. But if I add all 12 month balances and divide by 12, I get an average balance of less than the required $750,000 instead of higher.  How do I get Turbo Tax to handle a different allowable method of calculating average balance?

[Mike9241]

you'll probably have to enter the interest deduction, fudging some of the numbers since TurboTax cannot calculate average monthly balances, total them, and then divide by 12. Note that some OP have posted that they have received notices from the IRS about miscalculated mortgage interest deduction. This may be due to OP error. However, If the IRS uses its "preferred method" > beginning + ending divided by two, you might get one of these notices.