According to a post on Apple’s developer site, the company will start enforcing notarization prerequisites in February 2020.
Apple previously announced that “Mac software distributed outside the Mac App Store must be notarized by Apple in order to run on macOS Catalina.” The move is meant to improve security on macOS by ensuring only legitimate applications can be run.
To ease the transition, however, in September Apple announced the requirement would not take effect until the new year. With the latest announcement, Apple is informing developers their grace period is coming to an end and they will need to have Apple notarize their software before February 3, 2020. Any application not notarized by then will not be able to run on Apple’s latest macOS.