After you file

The IRS may adjust your federal tax return and remove the credit.

 

Before starting to amend the tax return, wait for the tax refund to be received or the taxes due to be paid and processed by the IRS.


See this TurboTax support FAQ on amending a tax return originally completed and filed using the 2020 TurboTax online editions - https://ttlc.intuit.com/community/amending/help/how-do-i-amend-my-turbotax-online-return/01/27577

The IRS Form 1040-X for amending a 2020 tax return is scheduled to be available on 03/18/2021 (subject to change)