If the return was already filed, you will need to wait until it has been processed and you have received your refund or confirmation that any tax due was paid. (If you file an amended return while your first return is being processed, it can cause extended delays for both returns) How do I cancel or undo an amended return in TurboTax Online?
The IRS may reject the return, then you would be able to go in and make any necessary changes to your tax return and resubmit.
How do I fix a rejected return?
How do I amend my 2019 TurboTax Online return?
Amended returns can only be mailed. It is suggested that it be mailed certified with return receipt (or other tracking service) to verify that the IRS receives it.
You can check the status of the amended return here, but allow 3 weeks after mailing.
How do I track my amend status?
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