I just got my download link for Turbotax 2018 Premier, and it installed and (so far) seems to work fine on my El Capitan machine. Other Mac users will recall that when installing 2017, they received a warning that starting in 2018, Sierra would be a minimum requirement. When starting up 2018, I got the same warning (but for 2018, not 2019), but like I said, it seems to work.
I’m posting to inform fellow users of older Mac machines, and to ask if there may be some hidden problem that’ll bit me later.
Thanks for this info. Poking around a bit, I see that Apple says later versions of its operating system have enhanced security. Because security is such a critical issue for tax software, Intuit may be hedging its bets even if the software functions perfectly on the older OS.