A modifier provides the means by which the reporting physician or provider can indicate that a service or procedure that has been performed has been altered by some specific circumstance but not changed in its definition or code.
Level I modifiers are codes and descriptors copyrighted by the American Medical Association's current procedural terminology (CPT).
Level II modifiers are codes and descriptors approved and maintained jointly by the alpha-numeric editorial panel (consisting of CMS, the Health Insurance Association of America, and the Blue Cross and Blue Shield Association).
| Modifier | Description | Effective | |
|---|---|---|---|
| AS | Physician assistant, nurse practitioner, or clinical nurse specialist services for assistant at surgery | Jan 01, 1999 | |
| AT | Acute treatment (this modifier should be used when reporting service 98940, 98941, 98942) | Jan 01, 1998 | |
| AU | Item furnished in conjunction with a urological, ostomy, or tracheostomy supply | Jan 01, 2003 | |
| AV | Item furnished in conjunction with a prosthetic device, prosthetic or orthotic | Jan 01, 2003 | |
| AW | Item furnished in conjunction with a surgical dressing | Jan 01, 2003 | |
| AX | Item furnished in conjunction with dialysis services | Jan 01, 2003 | |
| AY | Item or service furnished to an esrd patient that is not for the treatment of esrd | Jan 01, 2011 | |
| AZ | Physician providing a service in a dental health professional shortage area for the purpose of an electronic health record incentive payment | Jan 01, 2011 | |
| BA | Item furnished in conjunction with parenteral enteral nutrition (pen) services | Jan 01, 2003 | |
| BL | Special acquisition of blood and blood products | Jul 01, 2005 | |
| BO | Orally administered nutrition, not by feeding tube | Jan 01, 2003 | |
| BP | The beneficiary has been informed of the purchase and rental options and has elected to purchase the item | Jan 01, 1997 | |
| BR | The beneficiary has been informed of the purchase and rental options and has elected to rent the item | Jan 01, 1997 | |
| BU | The beneficiary has been informed of the purchase and rental options and after 30 days has not informed the supplier of his/her decision | Jan 01, 1997 | |
| CA | Procedure payable only in the inpatient setting when performed emergently on an outpatient who expires prior to admission | Jan 01, 2003 | |
| CB | Service ordered by a renal dialysis facility (rdf) physician as part of the esrd beneficiary's dialysis benefit, is not part of the composite rate, and is separately reimbursable | Jan 01, 2004 | |
| CC | Procedure code change (use 'cc' when the procedure code submitted was changed either for administrative reasons or because an incorrect code was filed) | Jan 01, 1997 | |
| CD | Amcc test has been ordered by an esrd facility or mcp physician that is part of the composite rate and is not separately billable | Jan 01, 2004 | |
| CE | Amcc test has been ordered by an esrd facility or mcp physician that is a composite rate test but is beyond the normal frequency covered under the rate and is separately reimbursable based on medical necessity | Jan 01, 2004 | |
| CF | Amcc test has been ordered by an esrd facility or mcp physician that is not part of the composite rate and is separately billable | Jan 01, 2004 | |
| CG | Policy criteria applied | Jul 01, 2008 | |
| CH | 0 percent impaired, limited or restricted | Jan 01, 2013 | |
| CI | At least 1 percent but less than 20 percent impaired, limited or restricted | Jan 01, 2013 | |
| CJ | At least 20 percent but less than 40 percent impaired, limited or restricted | Jan 01, 2013 | |
| CK | At least 40 percent but less than 60 percent impaired, limited or restricted | Jan 01, 2013 |