Can I amend a pending 2020 Federal return I filed online today? I submitted the wrong amount for the first Economic Impact Payment. I reported $1200 instead of $2400.

You will not be amending, but you can get the return back and make changes if you follow the directions in this link and do it today.
 

I followed the directions in the link you sent me yesterday and was led to believe I would receive an email when my 2020 1040 SR was available to make a revision to the information regarding the Recovery Rebate Credit.  I have not yet received an email.

Thanks

I am not sure if you were sent the correct email because as far as I know, there are no issues regarding the Recovery Rebate Credit. What you will need to do is amend your 2020 return to correct the erroneous information. Here are the steps.

1. Log into turbo tax
2. In your landing page, scroll down to the bottom of the page.  You will see an option to amend (change) 2020 return.  Do not attempt this now because that option won't be available until IRS accepts your return.
3. Once you are in the amendment process, go to:
4. Federal Review. The first page that appears will be Let's make sure you got the right stimulus amount continue
5. The next screen asks Did you get a stimulus payment? yes
6. Here is where you edit and change your answers to the first and second round stimulus payments.
7. The amendment feature that I mentioned is not available now but I expect it will be ready sometime after the IRS accepts electronic filings.

MaryM428 - I clicked on link as you provided and was expecting to receive an email yesterday (2/8) when my return would be available to update.  I am still waiting for an email.  I have made several other posts and received as many different answers.  I know if this isn't corrected before it is filed with IRS on 2/12/2021 I will have to file an amended return which I was hoping to avoid.

@jmkelm Unfortunately the answer is no, you cannot amend a pending return. Your return needs to be accepted or rejected first.

If accepted, you will need to amend your return. If your return is rejected, you can make corrections.