If you filed before the $10,200 unemployment exclusion, the IRS will recalculate your return for you. There is no need for taxpayers to file an amended return unless the calculations make the taxpayer newly eligible for additional federal credits and deductions not already included on the original tax return.
See this IRS announcement May 14, 2021
I understand you filed your 2020 tax return prior to the signed American Rescue Plan allowing for an exclusion of some unemployment compensation.
The good news is you do not need to do anything! The IRS is automatically adjusting these returns and will process the additional refunds. The IRS did begin this process in mid-May, and will continue in phases through the summer.
The IRS is experiencing delays this tax season so unfortunately it requires some patience while you wait for the additional refund.
There are a couple reasons you would file an amended return. If the reduced adjusted gross income after the unemployment compensation exclusion made you newly eligible for a credit that was not on your original return. These are also listed on the IRS link.
**Mark the post that answers your question by clicking on "Mark as Best Answer"