If the W-2 amounts were not included you would need to Amend your return. However, you would need to first wait and see if you tax return is accepted or rejected after filing. If rejected, you can go back add the W-2's then re-submit your tax return. If accepted, you would need to wait until after you have received your tax refund and then Amend using Amendment Form 1040X. Here's additional information on how to Amend your 2016 tax return:
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