Intuit is clearly putting their Mac TutboTax customers at an awkward disadvantage by using an SDK that doesn't support versions of macOS older than Mojave. This decision is timed particularly badly because Apple just started a two-year transition from Intel chips to Apple's own silicon, so many users will want to wait until the model of Mac that they prefer is available with Apple silicon, rather than have to buy a Mac with Intel chips (knowing that Apple is transitioning away from them) or having to buy one of the three models released with Apple M1 silicon (even though none of those models are suitable for that user). A much wiser and much more customer-friendly decision would be to continue using an SDK that supports say, versions of the operating system released within the last eight years, as long as the generated code will also run on the most recent version of the operating system. That would be the most reasonable way for Intuit to resolve the problem. Assuming that Intuit refuses to help its customers (i.e., abandons its customers who are stuck on older versions of the macOS), there is another alternative users could try to help themselves - but it requires both some computer savvy and a willingness to take the risk of running an unsupported environment. That alternative is to use the "macOS Mojave Patcher" from http://dosdude1.com/mojave to patch Apple's Mojave installer so that it will install on SOME older Macs on which Apple doesn't support Mojave or to use the "macOS Catalina Patcher" from http://dosdude1.com/catalina to patch Apple's Catalina installer so that it will install on SOME older Macs on which Apple doesn't support Catalina.
