The TurboTax online editions are only for tax year 2016.
To complete a tax year 2015 return using TurboTax, you will need to purchase and download one of the 2015 desktop editions from this website - https://turbotax.intuit.com/personal-taxes/past-years-products/
Or, you can pull the forms and instructions from the IRS and State tax websites, and do them by hand.
In any case, a tax year 2015 return can only be printed and mailed; it cannot be e-filed.
