Supervising physician co-signature is not required for coding or billing purposes, but may be required by your state department of public health or state PA licensing board. I'd suggest doing a search of your state's government web site to locate the specifics of PA supervision requirements, or contacting the department itself for clarification. In the state where I work, for example, physician supervision requirements include "the review of the charts and records of the physician assistant on a regular basis as necessary to ensure quality patient care and written documentation by the supervising physician of such review at the facility or practice location where the physician assistant or supervising physician performs services." But they do not specifically require that the physician must co-sign every note.