Now you have to wait until the IRS either rejects or accepts your return. The IRS will begin processing returns on January 23, 2017. 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 will need to use a form called a 1040X. You cannot e-file an amended return. They have to be mailed, and it takes at least 3-4 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
If you don't report all of your income, then the IRS will send you a notice in the mail. All tax forms are sent to both you and the IRS. When you file a tax return the IRS matches the forms up with what you report on your tax return. If something is missing (and a computer will always catch a W-2), then they'll send you a notice and also a bill for anything you owe. If you have a refund, they probably won't bother letting you know (they're sneaky like that).