Does a service member have a mandatory responsibility to self report?

A soldier has the responsibility to report any and all problems to their respective command for situational awareness if nothing else. This goes for any soldier, not just an S2. While withholding, if not asked directly, doesn't violate regulations it does cause concerns over the character and morality of the soldier. If the soldier was asked directly then lied or attempted to cover it up then that is a different matter. For instance, an incident took place before or after enlistment but clearly failed to disclose it knowing that officials were required to know. The incident could be multiple ticket infractions, failure to disclose medical problems, drug abuse, history of violence, etc.

Gents thank you for the quick responses, I greatly appreciate all of the answers. Bottom line up front the service member clearance was suspended and is pending further investigation. DoD CAF requested more information and we are attempting to gather that information. My S2 and myself spent the majority of today trying to find a answer in Army Regulation that stated or at least strongly implied that a soldier must self report derogatory information to their chain of command, our efforts resulted in very loose translations in AR 380-67 and a few EX ORDS. The investigating officer wants something that’s a little more black and white. Again thank you for all of the responses especially so late in the evening.

For clearances, not only are you required to self-reporr derogatory info, but technically any major change, even if not derogatory, such as a marriage. It is rarely actually done (My S2 looked at me like I was crazy when I reported mine) and I am too long out of the PERSEC game to quote you references, but the requirement is there.