How to Get a Letter of Medical Necessity (2026 Guide)
Who can write a letter of medical necessity, what it costs, what it must say, and how to use it to get reimbursed from your FSA or HSA at any store.
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Short answer
A letter of medical necessity is a short, signed note from a licensed clinician saying a specific product or service is part of treating a health condition you have. With it, you can buy that item anywhere, pay with any card, and file for reimbursement from your FSA, HSA, or HRA. You can get one from your own doctor (a visit and a copay), from a telehealth visit, or online through Burst for $35 with a licensed clinician reviewing your request and signing the letter, usually the same day.
Once you have the letter, you can file the claim yourself or let Burst file it for you.
What is a letter of medical necessity?
A letter of medical necessity (people shorten it to LMN) is a clinician's written statement that connects a specific item to a specific diagnosis. It is not a prescription. A prescription tells a pharmacy what to dispense. A letter tells your plan why a gym membership, a walking pad, or a mattress counts as a medical expense for you instead of a general purchase. Plans ask for it on anything that most people buy for everyday reasons but some people need for a health reason. IRS Publication 502 is where the underlying rule lives: an expense counts when it is for treating or preventing a specific condition, not for general health.
What does a letter of medical necessity let you do?
It lets you pay for the item the normal way and get the money back out of your pre-tax account. Say you pay $600 over the year for a membership at a local gym on your Visa. With a letter on file, you submit the receipts and your plan pays you $600 out of your FSA or HSA, to your bank account or by check. Because that $600 went into the account before taxes, it cost you something closer to $420 to $460 in take-home pay, depending on your bracket. The store never sees your plan. Points, cash back, and installment plans still work because you paid the way you always do.
Who can write a letter of medical necessity?
Any licensed clinician who can evaluate you can write one: an MD or DO, a nurse practitioner, or a physician assistant, and in some states other licensed providers such as chiropractors or naturopathic doctors, for items within their scope. It does not have to be the doctor you see every year. What plans look for is a license, a signature, and a date. Your plan does not care whether the visit happened in an exam room or over a video call.
How much does a letter of medical necessity cost?
Between $0 and a few hundred dollars, depending on how you get it. The letter itself is rarely billed as a separate line; what you pay for is the clinician's time.
Way to get one | What it costs | How long it takes | What you walk away with |
|---|---|---|---|
Your own doctor | Your copay, about $27 on average for a primary care visit with employer coverage; roughly $130 to $200 self-pay | Days to weeks to get the appointment, then however long the office takes to write it | A letter on the practice's letterhead. Some offices have never written one and need you to explain what your plan wants |
A telehealth visit | $49 for a video visit at Amazon One Medical pay-per-visit; $89 at Teladoc without insurance | Same day to a few days | A visit note or letter, if the clinician agrees to write one. You still file the claim yourself |
Burst online | $35 flat, one time. Refunded automatically if the clinician decides a letter is not appropriate, and refunded if your plan later denies the claim | Under 2 minutes to fill out; signed letter emailed usually the same day | A signed, dated letter formatted the way plans expect, and Burst files the reimbursement claim for you |
What does the letter need to say?
Six things, and vague letters get bounced for missing one of them.
Your name, as the patient.
The condition being treated, named specifically (high blood pressure, chronic low back pain, insomnia), not "general wellness."
The item or service, described plainly enough that the receipt matches it. "Home treadmill" works. "Fitness equipment" is too loose for some plans.
Why that item helps that condition, in a sentence or two.
How long you need it. Most letters say 12 months.
The clinician's name, credentials, license state, signature, and the date signed.
If your plan ever asks what the letter is for, the answer is one line: "My clinician documented that this purchase treats a diagnosed condition. The letter and receipt are attached."
How long is a letter of medical necessity good for?
Most plans accept a letter for 12 months from the date it was signed. That covers repeat purchases of the same thing inside the window, so one letter for a gym membership covers every monthly charge that year. After 12 months you need a fresh one. Your plan sets the exact window, so a few are shorter.
What do people get letters for?
Anything a clinician can tie to a condition and a plan would otherwise treat as a personal purchase. The common ones, with the reason a clinician typically documents:
Item | What the clinician usually documents | Read more |
|---|---|---|
Gym membership | Obesity, high blood pressure, prediabetes, depression, cardiac rehab | |
Walking pad or treadmill | Weight management with a related diagnosis, joint pain, sedentary-related conditions | |
Mattress | Chronic back pain, sleep apnea, fibromyalgia | |
Sauna or cold plunge | Chronic pain, arthritis, recovery from injury | |
Air purifier | Asthma, allergic rhinitis, COPD | |
Supplements | A documented deficiency or a condition the supplement is used for | |
Wearable (Oura, Whoop, Apple Watch) | Sleep disorders, heart rhythm monitoring, a condition that needs tracking |
The mistake people make most often is asking for a letter that names a category ("exercise equipment") when the receipt says "Peloton Bike+." Ask for the letter to name the thing you are buying.
How to get a letter for your purchase
Go to app.getburst.com/request-lmn and answer a few questions about your health and the item you plan to buy. It takes under 2 minutes.
A licensed clinician evaluates what you submitted. If a letter is appropriate, they sign it and email it to you, usually the same day. If not, your $35 is refunded automatically.
Buy the item wherever you want, with whatever card you want. The store does not need to accept HSA or FSA cards and does not need to know about the letter.
Send Burst the receipt. Burst files the claim with your plan, and your plan pays you out of your FSA, HSA, or HRA. If the plan denies it, the $35 comes back to you.
Frequently asked questions
Do I need the letter before I buy?
Yes. The letter has to be dated on or before the purchase, so request it first, then place the order. Same-day is fine as long as the letter comes first.
Can I write the letter myself and have my doctor sign it?
You can draft it, but a plan wants the clinician's own judgment, credentials, and signature on it. A blank template you fill in and sign yourself is not a letter of medical necessity.
Does it have to come from my regular doctor?
No. Any licensed clinician who evaluates you can write one, including one you meet over a video visit or through an online service.
Does the store need to accept HSA or FSA cards?
No. You pay with any card and get reimbursed afterward. That is the point of the letter route; it works at stores that have never heard of an HSA.
Who decides whether my claim is approved?
Your plan administrator. A clinician writes the letter; the plan applies its rules to the claim. That is why Burst refunds the $35 if the plan says no.
Can one letter cover several purchases?
Yes, for the same item over the 12 months the letter is valid. A gym letter covers every monthly charge. A new type of item needs its own letter.
Related: Letter of medical necessity FAQ, How to file your letter for reimbursement, A letter of medical necessity vs. a prescription, and 50 products people get letters for.
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