How do I submit a letter of medical necessity?

Three primary justifications used by insurance payers and healthcare providers to establish medical necessity are diagnosis and treatment alignment, prevention of clinical deterioration, and adherence to accepted medical standards.

Core Justifications for Medical Necessity

• Diagnosis and Treatment Alignment: The service, test, or treatment must directly correspond to a documented diagnosis, injury, or specific set of presenting symptoms. It cannot be performed solely for general wellness, screening where unindicated, or personal convenience.
• Prevention of Clinical Deterioration: Documentation must show that without the specific intervention, the patient's health condition, functional capacity, or well-being would suffer significant, measurable decline.
• Adherence to Accepted Standards of Care: The treatment must match safe, effective, and widely accepted clinical guidelines rather than experimental, investigational, or unproven methods.

Yes, you can write a letter of medical necessity (LMN) for yourself if you are a licensed physician, but it is generally discouraged by tax and insurance experts due to a clear conflict of interest.

Key Considerations for Self-Authored LMNs

• Conflict of Interest: Writing your own letter for tax deductions (like an HSA/FSA reimbursement or medical expense deduction) creates a self-serving bias that insurance companies or the IRS may view as lacking credibility.
• Third-Party Verification: To pass an audit or insurance review, guidelines strongly recommend that a separate, independent healthcare provider who is actively treating you for the condition should evaluate and sign the document.
• Auditing Risk: If an HSA administrator or the IRS requests proof of medical necessity, a self-signed letter carries a high risk of rejection or denial because it lacks an objective, unbiased medical evaluation.

You can request a Letter of Medical Necessity (LMN) for free by contacting your primary care doctor directly during a regular visit or via your patient portal.

Ways to Get a Free Letter of Medical Necessity

• Your Primary Doctor: Ask your current physician or specialist who already knows your medical history. Schedule a routine appointment or send a message through your provider's online patient portal to request the letter at no extra charge.
• Provide a Template: Speed up the process by downloading a free Medical Necessity Letter Template. Fill in your personal details, diagnosis, and treatment information, then ask your doctor to review, sign, and put it on their official letterhead.

What the Letter Needs

To ensure your insurance or HSA/FSA administrator accepts the document without charging extra fees for revisions, make sure it includes:

• Patient Information: Your full name, date of birth, and policy or member ID number.
• Diagnosis: Your specific medical condition along with the correct ICD-10 diagnostic code.
• Treatment Description: The exact product, equipment, or service being requested.
• Clinical Rationale: An explanation of how the treatment treats or prevents your specific condition rather than serving general wellness.
• Duration: The expected length of treatment (such as a specific number of months or a lifetime for chronic issues).
• Provider Signature: A signature and date from a licensed healthcare practitioner.

Yes, a letter of medical necessity (LMN) can be denied by an insurance company, employer, or benefits administrator.

Even if your doctor writes a formal recommendation, payers evaluate the request against their own strict internal guidelines and policy definitions.

Common Reasons for Denial

• Unmet Criteria: The treatment or item does not match the insurer's specific clinical rules or qualifying diagnoses.
• Missing Details: The letter lacks required elements, such as a clear diagnosis, specific duration, or a detailed explanation of why standard alternatives failed.
• Exclusion from Plan: The service or product is a total exclusion under the terms of your specific health plan or benefit design.
• Step Therapy Rules: You have not tried or failed required "preferred" or lower-cost treatments first.

Steps to Take If Denied

• Request the Rationale: Ask the insurer for the exact written policy, clinical criteria, or reason code used to deny the LMN.
• File an Appeal: Submit an internal appeal within your plan's deadline (often 180 days).
• Provide Stronger Evidence: Ask your doctor to submit an updated letter that directly addresses the insurer's specific rejection reasons, backed by additional medical records or clinical guidelines.

Medical necessity means a healthcare service, treatment, or supply is needed to diagnose, treat, or prevent an illness, injury, or its symptoms based on standard medical practice.

Common Examples of Medically Necessary Care

• Diagnostic testing: Ordering an MRI for persistent, unexplained neurological deficits or severe back pain after conservative treatment fails.
• Surgeries: Performing an appendectomy for acute appendicitis or joint replacement for severe, disabling osteoarthritis.
• Treatments and therapies: Prescribing physical therapy to restore mobility after a stroke or chemotherapy for a diagnosed malignancy.
• Medical equipment: Supplying a CPAP machine for diagnosed obstructive sleep apnea or a wheelchair for severe mobility impairment.

Examples Requiring a Letter of Medical Necessity

Insurance plans or tax-advantaged accounts like FSAs and HSAs sometimes require a Letter of Medical Necessity for items that are not standard medical care:

• Air purifiers or humidifiers: Used to treat severe chronic asthma or respiratory conditions.
• Specialized infant formula: Prescribed when an infant has a rare metabolic disorder or severe medical condition, rather than standard feeding preferences.
• Gym memberships or massage therapy: Approved only if explicitly prescribed to treat a specific diagnosed condition like clinical obesity or chronic back pain.