You must ONLY put 2017 W-2 forms on the 2017 return ... forms for a prior tax year MUST be entered on those tax years ... you cannot mix them up or you will get a letter from the IRS.
If you still need to file or amend the 2016 return then you must use the downloaded 2016 program ... you cannot use the current 2017 online version.
If you started a 2016 tax
return using the online editions then see this TurboTax support FAQ for
completing the tax return - https://ttlc.intuit.com/questions/2559403-how-do-i-finish-a-prior-year-return-that-i-started-in-turb...
If you did not start a
tax return using the online editions then you will need to purchase and
download one of the 2016 desktop editions from this website - https://turbotax.intuit.com/personal-taxes/past-years-products/
A 2016 tax return can
only be printed and mailed, it cannot be e-filed.
