The MAC minimum system requirements for the 2017 TurboTax desktop CD/Download edition software installed on your personal computer is Mac OS X v10.11 or later (64-bit required)
See this TurboTax support FAQ for the MAC system requirements for the desktop editions - https://ttlc.intuit.com/questions/1899173-minimum-system-requirements-for-turbotax-mac-software
You can use the TurboTax online editions with your current Mac OS - https://turbotax.intuit.com/personal-taxes/online/
