In order to file your 2015 tax return, you will need to download the 2015 Desktop version of TurboTax Deluxe. The TurboTax Online program is updated each year with the tax regulations for each new tax season and cannot be used to file the 2015 return.

The link for purchasing the 2015 software can be found here:  https://turbotax.intuit.com/personal-taxes/past-years-products/

Once you have entered all of your information and the return is complete, you will need to print and mail the return to the IRS because the IRS does not allow e-filing of past-year returns. You can select your state from the list in this link to determine where to mail your return:  https://www.irs.gov/uac/where-to-file-paper-tax-returns-with-or-without-a-payment