The insurer wants a letter of medical necessity. What must it contain?
The insurer's own criteria, answered one by one with facts from the chart: diagnosis with code, history and what has been tried, why this service or drug and not the alternatives, the expected outcome and the risk without it, and the guideline that supports it. A letter that mirrors the criteria wins; a letter that describes the patient in general does not.
What to do, in order
- Step 1
Get the criteria first
Ask the insurer for the clinical policy or criteria for the service. The letter is written against that document, not from scratch.
- Step 2
Structure the letter to the criteria
One heading per criterion, each followed by the chart facts that meet it, with dates and values. Then diagnosis and codes, prior treatments with dates and outcomes, contraindications to alternatives, the requested service with codes, and the treatment goal.
- Step 3
Cite one guideline
The specialty society guideline or the FDA label that supports the service in this situation, with the edition and page. One authoritative source beats five vague ones.
- Step 4
Sign and attach
Signed by the treating clinician with credentials and NPI, dated, on letterhead, with the supporting records attached and listed.
The deadline that applies
The letter is part of the appeal, so the appeal deadline governs: at least 180 days from the denial on ERISA and ACA plans (29 CFR 2560.503-1; 45 CFR 147.136). For a pending prior authorization, send it within the plan's decision window so the request is not denied for missing information.
Calculate your date →Documents to gather
- The insurer's clinical policy or criteria
- The chart notes, labs and imaging that meet each criterion
- Prior treatment history with dates
- The guideline or label cited
Go deeper
Related questions
Can the patient write it?
The patient can write the appeal; the letter of medical necessity carries weight only with a clinician's signature.
How long should it be?
As long as the criteria require and no longer. One to two pages is typical.
The doctor's office has a template. Is that enough?
Only if it is edited to the insurer's criteria and this patient's facts. Generic templates are the most common reason letters fail.
Sources
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