Do you mean software to prepare returns for previous tax years? If so, those versions are available for Macs also.

See https://turbotax.intuit.com/personal-taxes/past-years-products/2017

In the past you had to download the full program to amend on Mac.  You have to call in and ask for it.

Contact Customer Service
5am-5pm Pacific Time (8-8 Eastern) Every Day until Oct 25, 2019
And until 9pm (12 midnight Eastern) on Tue 10/15/19
https://support.turbotax.intuit.com/contact/