Turbotax isn't letting me amend a return already e filed and accepted by IRS.

[boisverttaxes]

Is there an estimed date for the 1040X form to be available

[DoninGA]

If the return is accepted you will have to amend your original tax return. An amended return, Form 1040X, can only be printed and mailed to the IRS if the original tax return was not e-filed. The IRS will take up to 16 weeks or longer to process an amended tax return.

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)

[macuser_22]

Do not rush to amend - no hurry. You have 3 years to amend and amended returns are taking 4-6 months or longer to be processed so waiting a few weeks will make little difference and amending too soon might just compound the problem.