technically you're supposed to amend or justifiably go back to the accountant and tell him/her to amend the returns for free. if refused and the accountant is a CPA you can report them to your state's CPA society for unprofessional conduct. here's the tax trap of not amending. a few years down the road when you can no longer amend 2019 the IRS comes in and audits finding that "adjustment". they have every right to add back that adjustment to the 2020 return, so you would end up paying taxes on it twice.
can't tell you what to do in relation to the return because that would depend on how the extra $3K was included in income - either an asset like cash needed to be overstated or there was an m-1 adjustment.
