I have downloaded the 2017 Tax software to amend my 2017 tax return. How can I upload my .tax file into the software. I am using a Mac.

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 .tax file