Letter of medical necessity: the template that maps to policy criteria

What an LMN is for

An LMN is a written statement from the treating clinician explaining why the requested service is medically necessary for this patient. It is the single most important document in most appeals.

Generic templates lose. The LMN must reference the insurer's specific clinical policy bulletin and walk through each criterion.

The structure

1. Header: patient name, DOB, member ID, claim number, date of denial, name of clinical policy.

2. Diagnosis: ICD-10 codes with brief clinical context.

3. Treatment history: prior therapies tried, dates, outcomes, and reasons for failure or contraindication.

4. Policy mapping: each criterion in the bulletin, followed by the specific finding in the record that meets it.

5. Guideline citations: NCCN, ACR, AAO, AAN, ASCO, AAP, or relevant specialty society — whichever the bulletin itself references.

6. Conclusion: explicit statement that the requested service is medically necessary and consistent with the standard of care.

What to attach

Office notes covering the relevant 12 months, imaging or lab reports cited in the LMN, and any prior peer-reviewed publications cited by name.

Do not attach unrelated records. The reviewer is reading dozens of files; brevity wins.