You may, on occasion, find yourself in that strange situation where your current employment visa has expired, you are still employed by your employer of record but your employment visa extension application has not yet been finalized.
So, the question is, can you still work when you find yourself in this kind of twilight zone between old and new visa approvals.
The answer is yes, just so long as you have your extension application in the system and your continue to work for the employer who is the sponsor of your recently expired employment visa.
The situation is different, however, if your last employment visa has expired and your application to take up an employment with a new employer is currently being considered by the Hong Kong Immigration Department.
Until this change of sponsorship application is finalized, whether you’re in the twilight zone or not, you are not lawfully employable and so should not commence any of your new employment duties until the permission of the Director of Immigration has been secured.
(Which normally takes between 4 and 6 weeks assuming all your documentary ducks are lined up at the time you commence your application).