It's now 2020 and your solution doesn't work for mortgage paid off in 2019. When I put "0" for balance after entering the interest paid in 2019, TurboTax generates this error message in red: "Outstanding mortgage principal must have a value." The mortgage company didn't send a 1098 because the interest is under $600. How do I get past this page and still have my interest credited? Going through "Forms" and Step-by-Step as suggested in another 2019 post on this subject does not work for me. TurboTax needs to add a "Mortgage paid off last year" option as a workaround.
