You should not add a W-2 from a prior year on this year's return. To add a tax form to a prior year return, you can amend your return.
Income received must be recorded in the year it was earned and expenses must be deducted in the year they occurred.
Click
here to amend your 2016 TurboTax Online return.
To add your 2016 W-2 to your 2016 amended return, follow the amended instructions then select W-2.