You can review your return by clicking "View Forms" if you are on the screen "Let's take one last look at the return you're e-filing". You are not required to do so, but it is HIGHLY recommended as this is your last chance to catch any errors you might have made in your entries.

How do I e-file my personal (individual) tax retur... (intuit.com)

I thought I had already sent the 1040.

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@Susanrime wrote:

I thought I had already sent the 1040.

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Did you do this?

You complete your tax return by finishing all 3 Steps in the File section. In Step 3, to e-file your tax return, you must click on the large Orange button labeled "Transmit my returns now".

After completing the File section and e-filing your tax return you will receive two emails from TurboTax. The first email when your tax return was transmitted and the second email when the tax return has either been accepted or rejected.

@Susanrime Until you click a big orange button that says "Transmit my returns now"  you have not e-filed.  The IRS is not accepting/rejecting 2020 returns until February 12.  That means if you e-file now, the return just goes to sit on a server in pending status until then.  If you discover any mistakes after you e-file. you cannot fix them when the return is in pending.   If you have any doubts, questions  or uncertainties about what you have entered on your tax return---wait and e-file after you have all of it figured out.

Turbotax says I need to change some figures on taxes withheld -- computer won't let me enter figures.