Letter of Medical Necessity Template (Free, Copy-Paste)
Below is a letter of medical necessity template you can bring to your provider. It contains the six elements administrators actually check for. Copy it, fill in the bracketed fields, and let the provider amend the clinical wording — they are the one signing it.
Short answer: a usable letter names the patient, states the diagnosis, names the specific item, explains in one sentence how that item treats the diagnosis, gives an expected duration, and carries the provider's credentials and signature. Miss any of the six and the claim is likely to come back.
The template
[PROVIDER LETTERHEAD] [Date] To Whom It May Concern / [Plan administrator name] Re: Letter of Medical Necessity for [Patient full name], DOB [date of birth] I am a [credential, e.g. board-certified family physician] licensed in [state], licence number [number]. [Patient name] has been under my care since [date]. DIAGNOSIS [Patient name] has been diagnosed with [condition], ICD-10 [code]. RECOMMENDATION As part of the treatment plan for this condition, I am recommending [specific item, named precisely]. MEDICAL NECESSITY [One to three sentences explaining how this specific item treats, mitigates or prevents this specific diagnosis. This is the part the administrator reads. Be concrete: what the item does physiologically or functionally for this condition.] DURATION This recommendation is expected to remain necessary for [duration, e.g. 12 months / ongoing], at which point it will be reassessed. Please contact my office with any questions. Sincerely, [Signature] [Provider name, credentials] [Practice name, address, phone] [NPI number]
The six elements, and why each one is there
| Element | Purpose | What a rejection looks like without it |
|---|---|---|
| Patient name and DOB | Ties the letter to the account holder | Returned as unmatched |
| Diagnosis, ideally coded | Establishes there is a condition to treat | ”General wellness” — denied outright |
| The named item | Establishes what is being claimed | ”Exercise equipment” — queried or partially denied |
| The clinical link | The actual argument for necessity | Approved only if the reviewer fills the gap themselves |
| Duration | Sets how long the letter stays valid | Defaults to 12 months, or gets queried |
| Credentials and signature | Makes it evidence rather than a note | Not accepted |
Worked wording, by category
The clinical link is the only part that changes much between letters. These are the shapes that get approved — your provider should adapt them to your actual case, not copy them:
Mattress. “Medium-firm orthopaedic support is indicated to maintain neutral spinal alignment overnight and reduce nocturnal exacerbation of diagnosed lumbar disc degeneration. The patient’s current sleep surface does not provide adequate lumbar support.” See LMN for a mattress.
Air purifier. “A HEPA air filtration unit is indicated to reduce the patient’s exposure to airborne allergens in the home environment, which are a documented trigger for their diagnosed allergic asthma.” See LMN for an air purifier.
Humidifier. “Maintaining indoor humidity between 40 and 50 percent is indicated to reduce mucosal drying, which is a contributing factor in this patient’s recurrent sinusitis.” See LMN for a humidifier.
Treadmill. “Supervised progressive aerobic exercise is a component of this patient’s cardiac rehabilitation plan. Home treadmill access is indicated because the prescribed frequency cannot be met through facility-based sessions alone.” See LMN for a treadmill.
Sauna. “Regular controlled heat therapy is indicated as an adjunct in the management of this patient’s diagnosed [condition], for symptom relief and to support the prescribed activity plan.” See LMN for a sauna.
Gym membership. “Structured aerobic and resistance exercise at a frequency of [n] sessions per week is prescribed as primary management of this patient’s diagnosed [condition].” See LMN for a gym membership.
Before you send it
Three checks that prevent most avoidable denials:
- Date it before or around the purchase. A letter dated after the receipt reads as a retrofit.
- Confirm the format your administrator wants. Some require their own form alongside the letter. Two minutes on the phone.
- Keep the letter with the itemised receipt. Product, price, date — a card statement will not substantiate the expense on its own.
The plan-side rules, including what differs between an HSA and an FSA, are on using an LMN with an HSA or FSA. If you do not have a provider to write it, Truemed covers the online route.
Sources
- Internal Revenue Service, Publication 502: Medical and Dental Expenses — what counts as a qualified medical expense.
- Internal Revenue Service, Publication 969: Health Savings Accounts and Other Tax-Favored Health Plans — substantiation requirements for HSA and FSA distributions.
Frequently asked questions
Can I write the letter of medical necessity myself?
You can draft it, but you cannot sign it. The letter only carries weight because a licensed provider is attesting to the diagnosis and the clinical link. Drafting it and bringing it to your appointment is normal and saves the provider time, as long as they review, amend and sign it themselves.
Does the letter have to be on letterhead?
Most administrators expect provider letterhead or an equivalent that shows the practice name, address and contact details. Letterhead is not a legal requirement, but a letter without any identifying practice information is much more likely to be queried.
Does the letter need an ICD-10 code?
Not strictly, but include it if the provider will. A coded diagnosis removes any ambiguity about what condition is being treated, and administrators process coded letters faster because there is nothing to interpret.
Can one letter cover several items?
Yes, if the same diagnosis supports all of them and each item is named separately with its own clinical link. A letter that lists items without explaining why each one is indicated tends to get partially approved at best.