Do not file the amended return until you have received the original refund. If it turns out, for any reason, that the IRS changes the original refund, you'll be able to make the adjustment on the amended return. But if you've already filed the amended return you've got a problem.

It's possible that the IRS will notice the error in the estimated tax paid and adjust the original return accordingly, without you having to do anything. Then you won't need to file an amended return.

I have a similar problem.  The IRS asked me to provide information supporting what I reported on my 2018 tax return.  In gathering that information, I realized I had made a mistake and entered the incorrect amount from my 2018 W-2.  I still have not received my refund, but the amended return shows that I owe the IRS.  In fact, my refund should be less, but I should still be getting a refund.

I'm wondering how things worked out for you.  Did you file the amended return, or just wait to get the original refund from the IRS?

First this is something the IRS usually corrects for you automatically so you should NEVER mail in an amended return until the original return has fully processed and the original refund is in hand.  

If you do amend prior to getting the original refund then the amount on line 18 is wrong which is why you don't like the incorrect bottom line. 

Look at the form 1040X …

Column A should have the figures from the original return, Column C the corrected figures and Column B the differences between the other 2 which needs an explanation on page 2 of the form 1040X.

If you completed it correctly you will see an entry on either line 16 OR 18:

On line 16 should be the amount you paid with your original return. If you paid nothing already then this line should be zero.

On line 18 should be the amount of your original refund you received.  If you have not received your refund yet then you need to wait for it.  If the refund changes from what you expected then this line must reflect that change.

Then you will see your extra refund on line 22 OR  the new balance due you need to pay on line 20.

In my case, they haven't corrected it, but they have asked me for additional information.  That's what caused me to recognize my mistake.  I responded to them letting them know that there was a mistake in the original return and how much I think it affects my anticipated refund.  I guess we'll see where it goes from there.

I recently filed my 2021 taxes and realized I forgot the estimated taxes.  This message tells me I do not need to file an Amended Return.   Hopefully this is correct.  Thank you.

@nesutch 

IRS knows how much you paid.

if you forgot to enter it, IRS computers will make the adjustment.