To add, I noticed the same thing this year for 2020 taxes compared to 2019 taxes. My 2020 taxes shows a negative for the, "State and local taxes greater than $10,000" line, and comparing it 2019's within the latest tax software (Premier 2020) shows last year being $0.00. If I go in to the 2019 tax software and show the summary of this line it displays the negative number for 2019 appropriately.
This appears to be a software bug, when importing a prior year's tax document. Furthermore this bug is also in TurboTax 2020.
If in doubt, open the prior years TurboTax software to get the proper amount until this issue is addressed.
