225 ILCS 95/5.5

A physician assistant shall not be allowed to personally bill patients or in any way charge for services. The employer of a physician assistant may charge for services rendered by the physician assistant. All claims for services rendered by the physician assistant shall be submitted using the physician assistant's national provider identification number as the rendering provider whenever appropriate. Payment for services rendered by a physician assistant shall be made to his or her employer if the payor would have made payment had the services been provided by a physician licensed to provide medicine in all of its branches.