If you choose to use TurboTax to complete and file the 2016 and 2017 tax returns, then you will need to purchase, download and install on a personal computer one of the desktop editions for each tax year from this website - https://turbotax.intuit.com/personal-taxes/past-years-products/
Prior year tax returns can only be printed and mailed, they cannot be e-filed.
When mailing multiple tax years use a separate envelope for each tax year. Also consider using a tracking service return receipt required from the US post office to track the mailed returns and have proof the IRS received the tax returns.
