You will need to amend your 2015 tax return to include any W-2s or 1099s that were received after you filed. The data on these forms is specific to the tax year on the form. Any attempt to include the form in another year's tax return would be identified by the IRS matching program and would trigger a notice correcting that year's return.
Since you have filed your tax return and it has been accepted by
the IRS, you will need to file an amended 2015 return. Open your 2015 return, and TurboTax will guide you
through correctly entering your new data and printing Form 1040X. You may also
have to amend your state income tax return if you have a state income tax.
Please note that amended tax returns must
be filed by mail.
For more information, please see TurboTax
Guide - Amending Your Income Tax Return.
