[sstradling]

It depends. I trust my immediate supervisor (from experience), so I told her about my startup side project a month ago. I don't want to leave her short-handed, so I wanted her to have time to think of a succession plan.

OTOH, I officially let my chain of command know about my project last week (per company policy). I put it off as long as ethically possible because I do not have the same level of trust in them (also from experience). I do not know if there will be any repercussions.

If you trust (really trust) your supervisor, let them know. They'll appreciate it, and your team will thank you. If you don't, then don't. If you have IP agreements or other legal entanglements that they could use to destroy you, find someone with experience in those areas to advise you on a best path forward.