The IRS site say to use the most recent Form 1040-X (January 2020) and manually enter 2020. Turbo Tax says to wait for form to be ready at the end of March 2021? Help?

[fanfare]

the IRS instruction is for those getting the form now and moving ahead without TurboTax.

That is your call.

[HelenC12]

Per the TurboTax FAQ, forms availability, Form 1040X should be available 3/18/2021 and you'll be able to e-file the amended return, which may result in faster processing.

• If you manually print out and fill out the form, you'll have to mail in your amended return. 

See How to amend (change or correct) a return you already filed.

Generally, Form 1040-X,  Amended U.S. Individual Income Tax Return, must be filed within three years of the date the original return was filed, or within two years of the date the tax was paid, whichever is later.