To access your current or prior year online tax returns sign onto the TurboTax website with the userID you used to create the account - https://myturbotax.intuit.com/
Scroll down to the bottom of the screen and on the section Your tax returns & documents click on Show. Click on the Year and Click on Download/print return (PDF) and Download .tax file
The TurboTax tax data files can only be opened by the TurboTax software for the year of the tax data file.
TurboTax desktop software for prior tax years (2015 thru 2017) - https://turbotax.intuit.com/personal-taxes/past-years-products/
TurboTax does not support tax year 2011.
