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 it will be processed like an amended return.
However, here are two other options:
- 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 to your 1040 that you filed a return to get the stimulus check and that this is a corrected return.
- You can simply write ‘1040X amended return’ on the top of the paper 1040.
Right now the IRS is slowly processing paper returns, but there will be no way for your to efile, so this is your only option. Be prepared for a longer than usual processing time.