I'm not aware of any CMS rule that requires the NPP (or any other employee) who is performing 'incident to' services to themselves be enrolled or participating with Medicare. For 'incident to' services, they are simply acting as a staff member and carrying out the care plan of the physician and all claims are billed as if the physician performed the services and are paid based on the physician's relationship with Medicare, so there's no need for the NPP to separately enroll if that's all they are doing. Just keep in mind that this severely limits the NPP's role in that they can not treat any new patients, or new problems for existing patients, and cannot change the care plan unless their supervising physician re-evaluates the patient.