The IRS changed my 2018 tax return due to deceased spouses' trustee filing a different tax return as married, filing separately a month after I filed as married, filing jointly. IRS then redid the taxes without including allowable tax deductions and ended up saying I owed them thousands of dollars, plus interest. Can I still send an amended tax return that proves they need to repay the money they said I had to pay and the 2021 return $$ they confiscated? Any suggestions or advice would be appreciated.
An amended return is probably not appropriate. You need to go to a tax professional or tax lawyer who has experience handling IRS disputes. I suggest that you go right away, even though tax people are very busy right now, because the statute of limitations for 2018 ends in less than two weeks.