Found out this year 2021, that I made mistakes on 2019 and 2018 returns. Assume 401A was a retirement account for individuals and input as IRA; did not know that IRA is a standard account. Will need to amend these returns, will pay the different amount owed. The questions are: will I receive a penalty and interest on this amount owed? And is there a graph to estimate these charges? I believed the IRS would of caught my mistake, but did not and I did not hear from them on 2019 and 2018 returns.
