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 | |
|---|---|---|---|
| CL | At least 60 percent but less than 80 percent impaired, limited or restricted | Jan 01, 2013 | |
| CM | At least 80 percent but less than 100 percent impaired, limited or restricted | Jan 01, 2013 | |
| CN | 100 percent impaired, limited or restricted | Jan 01, 2013 | |
| CO | Outpatient occupational therapy services furnished in whole or in part by an occupational therapy assistant | Jan 01, 2019 | |
| CP | Adjunctive service related to a procedure assigned to a comprehensive ambulatory payment classification (c-apc) procedure, but reported on a different claim | Jan 01, 2018 | |
| CQ | Outpatient physical therapy services furnished in whole or in part by a physical therapist assistant | Jan 01, 2019 | |
| CR | Catastrophe/disaster related | Aug 21, 2005 | |
| CS | Cost-sharing waived for specified covid-19 testing-related services that result in and order for or administration of a covid-19 test and/or used for cost-sharing waived preventive services furnished via telehealth in rural health clinics and federally qualified health centers during the covid-19 public health emergency | Mar 01, 2020 | |
| CT | Computed tomography services furnished using equipment that does not meet each of the attributes of the national electrical manufacturers association (nema) xr-29-2013 standard | Jan 01, 2016 | |
| DA | Oral health assessment by a licensed health professional other than a dentist | Jan 01, 2011 | |
| E1 | Upper left, eyelid | Jan 01, 1999 | |
| E2 | Lower left, eyelid | Jan 01, 1999 | |
| E3 | Upper right, eyelid | Jan 01, 1999 | |
| E4 | Lower right, eyelid | Jan 01, 1999 | |
| EA | Erythropoietic stimulating agent (esa) administered to treat anemia due to anti-cancer chemotherapy | Jan 01, 2008 | |
| EB | Erythropoietic stimulating agent (esa) administered to treat anemia due to anti-cancer radiotherapy | Jan 01, 2008 | |
| EC | Erythropoietic stimulating agent (esa) administered to treat anemia not due to anti-cancer radiotherapy or anti-cancer chemotherapy | Jan 01, 2008 | |
| ED | Hematocrit level has exceeded 39% (or hemoglobin level has exceeded 13.0 g/dl) for 3 or more consecutive billing cycles immediately prior to and including the current cycle | Jan 01, 2008 | |
| EE | Hematocrit level has not exceeded 39% (or hemoglobin level has not exceeded 13.0 g/dl) for 3 or more consecutive billing cycles immediately prior to and including the current cycle | Jan 01, 2008 | |
| EJ | Subsequent claims for a defined course of therapy, e.g., epo, sodium hyaluronate, infliximab | Jan 01, 2000 | |
| EM | Emergency reserve supply (for esrd benefit only) | Jan 01, 1997 | |
| EP | Service provided as part of medicaid early periodic screening diagnosis and treatment (epsdt) program | Jan 01, 1997 | |
| ER | Items and services furnished by a provider-based, off-campus emergency department | Jan 01, 2019 | |
| ET | Emergency services | Jan 01, 2002 | |
| EX | Expatriate beneficiary | Apr 01, 2015 |