A:Answer Given that there are changes in tax law every year, using 2020 tax software for 2019 could/would subject to the scrutiny of the IRS and who wants that. Considering that you are asking this question, you apparently already have an issue with the IRS, your non/late filing for 2019. You might want to get a tax advisor to work with you as you will need some advice regarding your 2019 return.