How can I determine how a mistake occurred in my 2018 return?

The IRS sent me notice that I owe back money from an error on my 2018 return. It seems the mortgage interest was entered as double on the 1040 but I do not know how this happened. If this was an error with the software (I filed with turbotax), what course of action can I take?

posted

Use the TurboTax Audit Support Center and speak with an agent to get assistance with the IRS notice you received - https://support.turbotax.intuit.com/irs-notice/audit-support/

You would have a hard time providing it was a program error since that has apparently not been widely experienced.

One thing I've seen happen is if you imported any info from your bank it also imported the 1098 and Mortgage interest. Then you also manually entered it.