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. If
accepted, you should wait until you receive your refund or paid your
balance due to amend the return to add the dependent.
You should print and mail the amendment (it
cannot be e-filed) and allow about 16 weeks for processing.
See
How Do I
Amend a Return Already Filed?
