After filing my son's 2020 return I realized he only received $518.70 of the $600 stimulus payment received in January of 2020. I went back into Turbo Tax and put in the amount he actually received and it shows he has a credit due of $81. Will the IRS automatically increase his refund by this $81 or do I have to file an amended return? If I have to file an amended return what are the steps that need to be taken? Thanks
Yes, you will have to amend his return if he does not have the Recovery Rebate Credit on his 2020 return.
To amend his return, please see the instructions on page How to amend (change or correct) a return you already filed.
After you elect to amend, please follow the steps below:
His Recovery Rebate Credit will be the difference between what he was qualified for on his 2020 tax return less the amount of his first and second stimulus payments he has already received.
2020 Recovery Rebate Credit — Topic G: Correcting issues after the 2020 tax return is filed