Due to the Fed $10.2k exemption on unemployment, how can I adjust the tax payment amount on my 2020 return already filed? I don't want to overpay.

You can open your return and see the changes to get the corrected amount due.  Then you can pay at Payments.

The IRS will adjust if a credit is already on the return.

You can amend if the credit is not on your return and should be - after the IRS is done.

Some credits that could be added:

Earned Income Credit eligibility:

The greater of AGI or earned income must be less than:

• $15,820 ($21,710 for MFJ) with no qualifying children,
• $41,756 ($47,646 for MFJ) with one qualifying child,
• $47,440 ($53,330 for MFJ) with two qualifying children, or•$50,954 ($56,844 for MFJ) with three or more qualifying children. 

Child Tax Credit

• See What is the Child Tax Credit?  

• You can visit the IRS interactive tool for Child Tax Credit 
• visit IRS Pub 972 Child Tax Credit -page 4 for income details.

Education credit, retirement savings and more!