Certificate of Medical Necessity
Also written as: CMN — Certificate of Medical Necessity
A formal document completed by a prescribing clinician attesting that a specific piece of durable medical equipment or assistive technology is medically necessary for a named patient.
Full Definition
A Certificate of Medical Necessity (CMN) is a payer-required form that substantiates a patient's need for durable medical equipment, prosthetics, orthotics, or supplies. In the United States, CMS specifies standardized CMN forms for particular equipment categories (e.g., power mobility devices, oxygen). Editors reviewing CMNs must ensure internal consistency between the diagnosis codes (ICD), the described functional limitations, and the specific equipment requested. The CMN must be signed by the treating physician or authorized prescriber; an unsigned CMN is a common and significant error editors should flag. Not to be confused with a Letter of Medical Necessity, which is a narrative document; a CMN is typically a structured payer form.
Usage
Usage note: Capitalise the full term and acronym as a proper document type. Distinguish clearly from Letter of Medical Necessity in all documents.
In Context
- "The claims processor returned the Certificate of Medical Necessity because the physician's signature block had been left blank." — Insurance claim audit report
- "A CMN is a structured payer form; do not confuse it with the narrative Letter of Medical Necessity, which supplements but does not replace it." — Editorial training note