If your return has been submitted, you should wait to determine
if it has been rejected or accepted.
If rejected, you can go back and change or adjust your return to
include the W-2.
If accepted by the IRS,
you should wait until you receive your
refund or paid your balance due to amend the return.
You will need to print and mail the amendment along with your
W-2 (it cannot be e-filed) and allow about 16 weeks for processing.
See
How Do I
Amend a Return Already Filed?
