I've been using turbotax since 1996, and I think this issue is going to be the one that pushes me off it. As others have stated, the developer tools seem to support older releases, so it seems like it's intuit's decision to force us all to upgrade our OS every year. Of all the software I have on my Mac, TurboTax is the only one requiring me to move to Catalina. Even if I decided to upgrade one of our family machines for this year, it's just pushing the problem out a year or two and constant narrow release support bothers me . I guess the sooner I move the better. I love how the PC version still supports Windows 8.1 (from 2013). Anyway, I may have to give H&R Block a try this year.... looks like they are supporting additional older releases.
