Direct Supervision for NP

We have an NP that has started seeing patients on Fridays when her supervising physician is out. CMS guidelines state the supervising physician must be in the office suite in order to bill incident-to services to Medicare. Does this same rule apply to commercial payers as well? I have been unable to find any information on this in the reference materials from our larger commercial payers.

Thanks,

Jennifer Ralston, RHIT, CPC

Direct Supervision for NP