You will need the desktop version of the software to complete that 2016 return. It cannot be done online. TurboTax Online is only for the current tax year 2017 only. Please see steps to take below to finish your 2016 return.
And the 2016 return would then need to be prepared, printed and mailed. You cannot e-file a prior year return.
How do I finish a prior-year return that I started in TurboTax Online?
