If the return has been accepted, you will need to amend it. Currently, the feature is not yet available because the IRS has not released Form 1040X. When it is, you will be able to enter back into the program in order to prepare the amended return.
If the return has been submitted but not accepted, you will not need to amend if your return is rejected. You can go back into the return to correct any reason for the reject and add the W2 at that time.
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