The soonest opportunity to e-file an amended return would be the last week of March when Form 1040-X becomes available.
For the most recent status updates on IRS Forms Availability, see: IRS forms availability table for TurboTax.
The amended state return must be paper filed unless you live in Georgia, Michigan, New York, or Vermont.
Not all corrections require an amended(changed) return. For example, the IRS issued guidance March 1, 2021 stating that if the Recovery Rebate Credit was included in the 2020 tax return, but calculated incorrectly, the IRS would automatically make the adjustments and amending the return would not be necessary.
To make sure an amendment is necessary, see: Do I need to amend?
