| M2 | Medicare secondary payer (msp) |
| MA | Ordering professional is not required to consult a clinical decision support mechanism due to service being rendered to a patient with a suspected or confirmed emergency medical condition |
| MB | Ordering professional is not required to consult a clinical decision support mechanism due to the significant hardship exception of insufficient internet access |
| MC | Ordering professional is not required to consult a clinical decision support mechanism due to the significant hardship exception of electronic health record or clinical decision support mechanism vendor issues |
| MD | Ordering professional is not required to consult a clinical decision support mechanism due to the significant hardship exception of extreme and uncontrollable circumstances |
| ME | The order for this service adheres to appropriate use criteria in the clinical decision support mechanism consulted by the ordering professional |
| MF | The order for this service does not adhere to the appropriate use criteria in the clinical decision support mechanism consulted by the ordering professional |
| MG | The order for this service does not have applicable appropriate use criteria in the qualified clinical decision support mechanism consulted by the ordering professional |
| MH | Unknown if ordering professional consulted a clinical decision support mechanism for this service, related information was not provided to the furnishing professional or provider |
| MS | Six month maintenance and servicing fee for reasonable and necessary parts and labor which are not covered under any manufacturer or supplier warranty |