This Solution provides compatibility information for Big Business and macOS 10.15 Catalina, scheduled for release September 2019.
In an unusual move, Apple released a Public Beta(6918)
Big Business 12.3 and higher are supported on macOS Catalina. Big Business 12.3 is certifed compatible with macOS Mojave. To install you may need to go System Preferences, Security, click the Lock and Allow installation.
Big Business 11 is not supported on macOS Catalina. Big Business 11 is certified compatible with macOS High Sierra and is supported on macOS Mojave.
Big Business 10 is not supported on macOS Catalina. Big Business 10 is certified compatible with macOS 10.12 Sierra.