After you file

If you submitted the non-filer form, it was processed by the IRS as an original filed return.  Any subsequent filing cannot be filed electronically; it has to be mailed in. If you file your return with a Form 1040X in order to rectify this, it will be processed like an amended return. 

However, you don’t need to fill out the 1040X to get your return processed.  All you need to do is:

• Indicate in a cover letter on your 1040 that you filed a return to get the stimulus check, and that this is a corrected return.

Or

• You can just write ‘1040X amended return’ on the top of the paper 1040.

Internal Revenue Manual 21.5.3.4 General Claims procedures states:  ‘An informal written inquiry that includes everything necessary to input a correct adjustment’ will be processed.

Here's how to print your return:

1. Open or continue your return.
2. Select Tax Tools in the left menu (if you don't see this, select the menu icon in the upper-left corner).
3. With the Tax Tools menu open, you can then:

• Select Print Center and then Print, Save, or Preview This Year's Return to preview your entire return, including all forms and worksheets (you may be asked to register or pay first).
• View only your 1040 form by selecting Tools. Next, select View Tax Summary in the pop-up, then Preview my 1040 in the left menu.