Form 1040X for taxes 2020 when it would be available for amends?
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 03/25/2021 (subject to change)
I can't do anything until March 25th according to Turbotax website. That's not right. I just try to correct my taxes 2020