First of all, you do nothing. You wait until the IRS has completely process your income tax return and you've received any refund you're due or your check has been cashed if you owed.
I'd advise waiting until some time to at least mid-February before even attempting to amend your income tax return. You just don't want to get the IRS confused!
can guide you on how to amend. Amended income tax returns cannot be e-filed, they must be mailed.
Actually, there's another course of action - or inaction - that you could take, if you choose, and that is to do absolutely nothing. The IRS almost certainly will, at some point, recognize your mistake and fix it for you, sending you a bill for the taxes due, (if any), with some amount of interest added.
But I'd suggest simply amending at the appropriate time.
Did you e-file without it? Has the return been accepted?
You cannot change or add anything on the return that you just e-filed, nor can you stop it. It is too late, just like when you put an envelope in a US mailbox on the corner.
If you left out a W-2, or a dependent, or a 1099 etc…DO NOT change your return while it is pending. The changes will go nowhere.
Now you have to wait until the IRS either rejects or accepts your return. If your return is rejected, you will be able to go into your account and make the necessary changes to your tax return and re-submit your return.
If the IRS accepts your return, however, then you have to wait longer until it has been fully processed and you have received your refund. THEN you can prepare an amended tax return and mail it in. You have to be able to work from that return exactly the way it was when it was e-filed originally. You will need to use a form called a 1040X. You cannot e-file an amended return. They have to be mailed, and it takes about 4 months for the IRS to process an amended return.
Meanwhile, DO NOT go in and start changing anything on your return in the system, or you will make a mess for yourself. Sit tight and wait until you see what the IRS does with the return you just e-filed