2020 tax audit

I am being audited on my 2020 return, for my mortgage interest deduction.

I filled out the deductible home mortgage Interest Worksheet, but the software does not seem to have corrected the interest applied by the factor on line 15.

Not only must I explain this to an IRS inspector, but I am trying to understand why it happened.

I have used TurboTax for over 20 years and never had an issue like this.