How to Get a Letter of Medical Necessity (Free Template)

A Letter of Medical Necessity (LMN) is a signed statement from a licensed healthcare provider confirming that a specific product or service is medically necessary to treat, diagnose, or prevent a specific diagnosed medical condition. For HSA and FSA purposes, the LMN serves one critical function: it converts a gray-area product from an ineligible general wellness purchase into a qualified medical expense reimbursable with pre-tax dollars.

Without an LMN, your HSA or FSA plan administrator cannot verify that a dual-use product — like a smart ring, light therapy lamp, fitness tracker, or biofeedback device — was purchased for a legitimate medical reason. The LMN creates the documented connection between your diagnosis and the product, satisfying the IRS requirement that the expense be "primarily for the prevention or alleviation of a physical or mental defect or illness."

LMNs are not new to healthcare — they have long been used for durable medical equipment (wheelchairs, CPAP machines) covered by insurance. Their application to consumer health devices purchased through HSA/FSA accounts is a natural extension of the same logic.

Any licensed healthcare provider who is treating you for the relevant condition can write a valid LMN. Qualified providers include: primary care physicians (MD, DO), nurse practitioners (NP), physician assistants (PA), specialists of any relevant type (cardiologist, neurologist, psychiatrist, endocrinologist, sleep medicine physician, etc.), licensed clinical psychologists (PhD, PsyD), and licensed clinical therapists (LCSW, LPC) for mental health-related products.

The provider must hold a current, active license in your state and must have an established patient-provider relationship with you. A genuine clinical consultation is required — a rubber-stamp LMN from a provider who has never evaluated you is not valid and could constitute fraud.

Telehealth providers who have conducted a proper video or telephone consultation can write valid LMNs. If you do not have a current primary care physician, telehealth platforms offer consultations that can include LMN writing for common conditions. Be cautious of services that market themselves exclusively as LMN-generation services with minimal clinical evaluation — most major HSA administrators have become skeptical of these.

Core required elements: (1) Patient's full name and date of birth. (2) Specific medical condition or diagnosis — use the clinical name and, ideally, the ICD-10 code. "Sleep apnea" is better than "sleeping issues." "Sleep apnea, ICD-10: G47.33" is best. (3) Specific product name and model — the exact item being purchased, not a general category. Write "Oura Ring 4" not "wearable health monitor." (4) Medical necessity statement — a brief explanation of why this specific product is needed to treat or monitor the named condition. (5) Provider information: full name, license number, practice name, address, phone number. (6) Provider signature. (7) Date of the letter.

Optional but recommended elements: the treatment period (e.g., "for the next 12 months" or "ongoing for chronic condition management"), the ICD-10 diagnosis code, and a note about the clinical basis for the recommendation (e.g., "patient's cardiologist has recommended HRV monitoring following recent AFib diagnosis").

One-page LMNs are standard. Longer is not better. Administrators are reviewing many claims; a concise, well-organized LMN with all required elements present is more effective than a lengthy letter that buries the key information.

[Date]

To Whom It May Concern:

I am writing on behalf of my patient, [PATIENT FULL NAME], Date of Birth: [MM/DD/YYYY], to confirm that the following product is medically necessary for the treatment of a diagnosed medical condition.

DIAGNOSIS: [Condition name — e.g., "Obstructive Sleep Apnea"] [ICD-10 Code if known — e.g., "G47.33"]

RECOMMENDED PRODUCT: [Full product name and model — e.g., "Oura Ring 4, Titanium"]

MEDICAL NECESSITY: [Patient name] has been diagnosed with [condition]. This device is recommended to [monitor/treat/manage] [specific clinical use — e.g., "nocturnal SpO2 levels and sleep architecture to support management of obstructive sleep apnea"]. General wellness devices that lack clinical monitoring capabilities are not adequate substitutes for this patient's needs.

This recommendation is effective from [start date] and covers a treatment period of [12 months / indefinite for chronic condition].

PROVIDER INFORMATION: Name: [Full name] | License #: [State license number] | Specialty: [e.g., Sleep Medicine] | Practice: [Practice name] | Address: [Full address] | Phone: [Phone number]

Provider Signature: _________________________ Date: ______________

Copy this template, complete all bracketed fields, and bring the printed letter to your appointment. Most providers can review and sign it in under five minutes. Email it to their office before the appointment so it is ready to sign when you arrive.

Step 1 — Identify your condition and provider. Determine which diagnosed condition supports the product you want to buy. Review your medical records or recall your diagnoses. Identify the provider best positioned to write the LMN (typically the physician or specialist managing that condition).

Step 2 — Schedule an appointment. In-person or telehealth both work. You can often request an LMN during a regular check-up or follow-up appointment rather than booking a dedicated LMN visit. Call the office ahead of time and mention you will need an LMN signed during the visit — this allows the provider to allocate the time.

Step 3 — Prepare your materials. Print or have ready: the completed LMN template (with all fields except the signature and date pre-filled), documentation of your diagnosis if not already in the provider's records, a clear description of the product you are purchasing.

Step 4 — Have the LMN signed. Your provider reviews the letter, makes any modifications they deem appropriate, signs, and dates it. Request that they use their practice letterhead if possible — some administrators find letterhead more credible, though it is not strictly required.

Step 5 — Purchase your product. Use your HSA/FSA card at checkout if the merchant accepts it, or pay with a regular card and save the receipt or order confirmation.

Step 6 — Submit your reimbursement request. Log in to your HSA/FSA administrator portal, navigate to "Submit Claim" or "Reimbursement Request," upload the signed LMN and proof of purchase, and submit. Most administrators respond within 3-10 business days.

Mistake 1 — Vague diagnosis. Writing "general wellness monitoring" or "overall health improvement" instead of a specific clinical condition. Every rejected LMN for vagueness could have been approved with a more specific diagnosis.

Mistake 2 — Wrong or missing product name. The LMN must name the specific product purchased. "Wearable device" or "health monitoring equipment" is not sufficient. Write the exact product name and model: "Oura Ring 4," "Apple Watch Series 10," "Verilux HappyLight 10,000 Lux."

Mistake 3 — Unsigned or undated LMN. An LMN without both a provider signature and a date is automatically invalid. Always verify both are present before leaving the appointment.

Mistake 4 — Provider not currently licensed. Retired physicians, providers whose licenses have lapsed, or providers who are not licensed in your state cannot write valid LMNs. Verify your provider's license status on your state medical board's online directory.

Mistake 5 — Submitting the LMN alone without a receipt. The LMN establishes medical necessity but does not prove you made the purchase. Always submit the LMN together with proof of purchase (receipt, order confirmation, or credit card statement showing the specific item and amount).

Mistake 6 — LMN written for the wrong product category. If you purchased a Fitbit but your LMN references the Apple Watch, the claim will be rejected. Make sure the product named in the LMN exactly matches what you purchased.

Most HSA and FSA plan administrators accept LMNs as valid for 12 months from the date of issue. After that period, you may need a new LMN to continue claiming expenses for the same product category. The expiration policy varies by administrator — always confirm when submitting your first claim.

For chronic or permanent conditions (Type 1 diabetes, permanent hearing loss, ongoing cardiac arrhythmia), an LMN may be written with an indefinite or multi-year treatment period. Ask your provider to note the treatment duration in the letter. If your administrator allows it, this reduces the administrative burden of annual LMN renewals.

For renewable LMNs: most administrators accept a brief follow-up visit or even a telehealth check-in as the basis for a renewed LMN. You do not need an elaborate new evaluation — a provider confirming that your condition is ongoing and the device remains medically necessary is sufficient.

Yes — LMNs written by licensed providers during telehealth consultations are valid for HSA/FSA purposes. The CMS and HIPAA rules that govern telehealth in the United States recognize a telehealth consultation as a legitimate clinical encounter, and IRS guidance does not distinguish between in-person and telehealth for LMN purposes.

The same requirements apply: the provider must be licensed in your state, must have conducted a genuine clinical evaluation (not a perfunctory rubber-stamp service), and must sign the LMN using their name and license number.

Be cautious of services whose business model is primarily generating LMNs with minimal clinical interaction. These "LMN mills" are increasingly recognized as a compliance risk by HSA administrators. A telehealth consultation with your regular physician or a legitimate telemedicine platform (Teladoc, MDLive, your insurer's telehealth portal) carries far more credibility than an unknown service whose only product is signed LMNs.

Smart rings and fitness trackers: Oura Ring 4, Apple Watch Series 10, Fitbit Charge 6, Whoop 4.0, Garmin Forerunner 255, Withings ScanWatch. Required LMN conditions: cardiac arrhythmia, sleep apnea, diabetes, chronic fatigue syndrome.

Light therapy devices: Verilux HappyLight, Carex Day-Light Classic Plus. Required LMN conditions: Seasonal Affective Disorder, major depressive disorder with seasonal pattern, circadian rhythm sleep disorder.

Biofeedback devices: Muse 2 Brain Sensing Headband. Required LMN conditions: anxiety disorders, PTSD, chronic stress with clinical symptoms.

Sleep devices: Hatch Restore 2. Required LMN conditions: insomnia disorder, circadian rhythm disorder.

Baby monitors: Owlet Dream Sock. Required LMN conditions: apnea of prematurity, congenital heart conditions, documented cardiac or respiratory risk.

Weighted blankets. Required LMN conditions: autism spectrum disorder, anxiety disorders, sensory processing disorder.

General rule: if a product appears in both the electronics aisle and the medical device section — or if it is marketed to healthy consumers as well as patients — assume an LMN is required.

These two documents serve different purposes and should not be confused. A prescription is a legal order for a controlled, regulated medication or medical device — issued under strict FDA and DEA rules. Prescriptions are required to purchase prescription-only medications, CPAP machines, prescription-strength topical treatments, and similar regulated items.

An LMN is not a prescription. It is an explanatory letter establishing medical necessity for a product that is not prescription-only but exists in a gray area between medical and consumer use. You do not need a prescription to purchase an Oura Ring, a Fitbit, or a light therapy lamp — but you need an LMN to claim them as qualified HSA/FSA expenses.

For HSA/FSA submission purposes: prescription medications and items are submitted through the pharmacy or with the prescription label as documentation. LMN-required items are submitted with the signed LMN letter plus a purchase receipt. Mixing up these processes leads to unnecessary rejections — submitting a prescription where an LMN is needed, or vice versa.

A rejection on the first submission is common for LMN-required products and is not a final determination. The most frequent reasons for rejection: missing documentation, vague diagnosis, product name mismatch, or the LMN was not recognized as originating from a licensed provider.

The appeal process: call your plan administrator's member services number (on the back of your FSA/HSA card) and ask specifically: "What documentation is required to approve this claim?" Note the name of the representative and the date of the call. Resubmit with a revised, complete LMN that addresses the specific deficiency, along with a new cover letter explaining the resubmission.

If rejected a second time: escalate to your HR benefits team or benefits broker. They can often contact the administrator directly to facilitate approval. The majority of legitimate LMN-based claims that are initially rejected are ultimately approved with proper documentation and appropriate escalation.

Create a dedicated filing system for HSA/FSA documentation. For each LMN-required purchase, maintain a folder containing: the signed original LMN (scan and save a digital copy to cloud storage), the purchase receipt or order confirmation showing the product name and amount, the claim submission confirmation from your administrator, and the approval or reimbursement confirmation.

Label folders by year and product (e.g., "2026 — Oura Ring"). Back up digital copies to cloud storage. Under IRS guidance, retain HSA records for a minimum of 3 years from the date of the tax return, though 7 years is the recommended standard given the potential for HSA-specific IRS inquiries.

If you switch HSA administrators — which commonly occurs when changing employers — your documentation remains valid. You may need to resubmit previously approved claims to a new administrator, but a properly documented and signed LMN remains enforceable for the period specified in the letter.