I was hoping someone could clarify the rules on this. When you have an np doing the service and their supervising provider signs off on the documentation you would bill this with an sa modifier correct? Also what if you have a new doctor to the practice who has not been credentialed with all insurance carriers can you bill under another dr or do you wait til the credentialing is complete?? I work in a pediatric practice and i wasn't sure if this was different since we don't see any medicare patients although i realize we all have to follow the cms rules. Any info on this would be appreciated. 