superseding a return?

[Catherine]

Client whose return was final and submitted over a MONTH ago now sends a new 1099-MISC with over $10K income.  Is it possible, this year, even to do a superseded return?  Or are we stuck amending, later, (maybe even by e-file)?

Now I will take a minute to grumble about these nincompoops - apparently they KNEW about this, and expected it, but said nothing to me and cheerfully accepted the final (now not-final) returns, signed on penalty of perjury, and let me submit them.  I think their bill just went UP substantially. 

[Abby Normal]

Amended returns received before the deadline are considered superseding. I think the IRS (when they finally get around to opening the mail) can handle the return either way.

[Catherine]

4 minutes ago, Abby Normal said:

when they finally get around to opening the mail

That will be months.  Guess I'll handle it as an amended return.  Thanks!