CPT modifier used for assistant surgeon. Surgical assistant services may be identified by adding the modifier -80 to the usual procedure number(s). This modifier may affect reimbursement. Some insurance policies do not include payment for assistant surgeons such as for 1-day surgery but do pay for major or complex surgical assistance. In some instances, prior approval may be indicated due to the patient’s physiologic condition. Medicare will not pay assistant surgeons for operations that are not life threatening. Therefore Medigap insurance will not pay on this service because the service is nonallowable. Assisting surgeons usually charge 16% to 30% of the primary surgeon’s fee.