Only 2016 is available online.
The prior tax years (2013 thru 2015) are only available using the desktop software.
You can purchase 2015 software directly from TurboTax as a download here to install on your computer:
<a rel="nofollow" target="_blank" href="https://turbotax.intuit.com/personal-taxes/past-years-products/">https://turbotax.intuit.com/personal-taxes/past-years-products/</a>
Or you may find it at a discount from a reputable retailer like Amazon. If purchased outside of TurboTax, be aware that Deluxe comes in 2 versions--one that is Federal only, and one that is Federal and State. So if you choose Deluxe, be sure to select the correct one for your needs. Deluxe purchased from TurboTax has both Fed and State programs.
Desktop Premier and Home and Business only come with both Fed and State programs. Desktop Basic does not include a state program and cannot import from ItsDeductible.