Do you keep your security clearance if you get discharged?

No. You’re debriefed and you no longer have an active clearance. There’s a time after that when your clearance can be reactivated fairly quickly if you go to a govt or civilian job that requires a clearance.

So you will still "have" a good "x" level clearance. But it wont be "active" your future employer can activate that same clearance for a whoooooole lot cheaper and quicker than getting a new hire with no clearance. Thus the ol' "having a clearance helps with getting an outside job."

It generally stays in the system for 2 years (unless it expires.