To do your 2015 return using TurboTax you need the desktop tax software and the return must be mailed in you cannot e-file a prior year return. A prior year return cannot be done online, the Online version is only to prepare the current year’s return. You can go to the following website to purchase and download TurboTax’s 2015 desktop tax software.
http://turbotax.intuit.com/personal-taxes/past-years-products.jsp
