Forget to claim a credit in tax year 2020, plan to send 1040-x to correct it.
By IRS web, " If you need to amend your Form 1040, 1040-SR, 1040-NR, or 1040-SS/PR for the current or two prior tax periods, you can amend these forms electronically using available tax software products"
Does it mean I need file by paper?
An amended 2020 return cannot be e-filed. It has to be sent in by mail. Do not expect quick results--it will take the IRS four to six months to process an amended return.
You can watch for information here:
https://www.irs.gov/Filing/Individuals/Amended-Returns-(Form-1040-X)/Wheres-My-Amended-Return-1
f you prepared your original tax return using TurboTax, log in to your account, open the tax return you already filed, and click on the link to amend your return. From there, the software will walk you through the process of filing the amendment.