After you file


@JP134 wrote:

I mistakenly claimed the rebate credit on my tax return and later discovered that I had actually received it in March 2021.  Due to my error I went from a refund to now actually owing tax.   Should I pay the amount by 4/18/22 before I receive a notice from the IRS?


The IRS will adjust your tax return accordingly since they know that the 3rd stimulus payment was sent to you.

You do not need to amend the 2021 tax return.