Letter of Medical Necessity FAQ: 30 Common Questions Answered (2026)
The 30 most common questions about Letters of Medical Necessity for FSA and HSA, answered in one place. What qualifies, what an LMN actually says, how reimbursement works, and the edge cases people get wrong.
12 minute read
Hi, I'm Shubhi. We get the same questions about LMNs over and over, so this is the comprehensive FAQ in one place.
Short answer. A Letter of Medical Necessity (LMN) is a brief document from a licensed clinician documenting that a specific product or service is part of how you're managing a specific health situation. Under IRS Publication 502 and Notices 2006-69 and 2007-2, expenses that treat, mitigate, or alleviate a documented medical condition are FSA and HSA reimbursable. The LMN provides the documentation. Below are the 30 most common questions about LMNs, the rules behind them, and how to use one in practice.
If that already describes you, the request takes about three minutes and you can skip the rest of this guide.
What an LMN is
What is a Letter of Medical Necessity?
A document from a licensed clinician naming a specific health situation and connecting it to a specific product or service you're purchasing or using.
What's the difference between an LMN and a prescription?
A prescription authorizes a specific medication. An LMN documents that a non-prescription product or service is part of treating a medical situation.
Who can write an LMN?
Any licensed clinician (MD, DO, NP, PA, naturopath in licensed states). Most consumer LMN providers use telehealth nurse practitioners.
How long is an LMN valid?
Typically 12 months from the issue date. After that, you need a refreshed LMN for ongoing recurring purchases.
Does the LMN have to be on letterhead?
Most plan administrators expect formal documentation including the clinician's credentials, signature, and the date. Burst's LMNs are formatted to plan-admin standards.
What qualifies for an LMN
What products need an LMN?
Anything dual-purpose under IRS rules: fitness equipment, mattresses, saunas, recovery tools, supplements (most), wearables, gym memberships, specialty foods, water and air filtration, etc.
What products are eligible without an LMN?
Prescription medications, doctor visits, copays, OTC medications (post-CARES Act), period products (post-CARES Act), dental, vision, prenatal vitamins, breast pumps.
Can I get an LMN for cosmetic procedures?
Generally no. Cosmetic Botox, hair restoration without alopecia, and aesthetic procedures don't reimburse. Functional Botox (chronic migraine, TMJ, hyperhidrosis) does.
Can I get an LMN for travel?
Travel for medical care (treatment, surgery, specialist visits) is eligible. Travel for general wellness isn't.
Are gym memberships covered?
With an LMN naming a documented medical context (cardiac rehab, weight management with comorbidity, depression treatment plan), yes.
How the LMN process works
How do I get an LMN?
Use a service like Burst (5 minutes online), TrueMed, Flex, or your existing healthcare provider. Burst is $25 flat with full refund if declined.
Can I get an LMN for past purchases?
Per IRS guidelines, LMNs must be for purchases made on or after the LMN request date. Get the LMN first, then buy.
How long does it take to get an LMN?
Burst typically delivers within 5 minutes for a standard request. Complex situations (multiple conditions, large dollar amounts) may take longer.
What if my LMN gets denied by my plan administrator?
Plan admins occasionally deny claims. Burst's clinicians write LMNs in approval-tested format and rework them if denied.
Can I have multiple LMNs at once?
Yes. You can have separate LMNs for separate medical contexts (e.g., one for cardiac rehab equipment, another for sleep-related products).
Reimbursement and plan administrators
How does the reimbursement actually flow?
Pay with any card. Submit receipt + LMN to your plan administrator. Reimbursement lands in your bank account from your FSA or HSA balance.
Which plan administrators accept LMNs?
All major ones: Optum, HealthEquity, Fidelity, HSA Bank, PayFlex, Navia, WEX, FSAFEDS, Bank of America. Smaller TPAs vary.
Can I use my HSA card directly at checkout for LMN-eligible items?
Sometimes. Default-eligible items auto-substantiate at IIAS-compliant retailers. LMN-required items typically need post-purchase reimbursement.
Is the LMN fee itself FSA/HSA eligible?
Yes.
How do I track LMN-eligible expenses?
Most plan administrators have submission portals. Keep a folder of receipts + the LMN as a single PDF for easy reference.
Edge cases and gotchas
Can I cover multiple products on one LMN?
Yes, when each product fits a documented medical context. Burst's LMNs typically cover a category (e.g., "all home cardio equipment for cardiac rehab") rather than individual items.
Can I cover memberships and subscriptions on an LMN?
Yes — Peloton All-Access, Tonal+, Hydrow, Whoop, iFit, Mirror, Apple Fitness+ when paired with the documented context. Recurring while the LMN is current.
What if I'm covering a family member?
HSA covers spouses and tax dependents. The LMN should be in their name if the product is for them.
What if my plan year ends?
FSA: typically end-of-year deadline for new purchases (some plans have grace periods or carryover). HSA: no expiration, funds roll over.
Can I switch from TrueMed to Burst mid-purchase?
Yes. The LMN is what your plan admin evaluates. The provider doesn't matter as long as the LMN is properly written.
Specific situations
Can I get an LMN for GLP-1 medications like Wegovy?
GLP-1s prescribed for type 2 diabetes are typically default-eligible. For weight loss without diabetes, eligibility depends on plan and may need an LMN.
Are running shoes covered?
Standard running shoes aren't eligible by default. Specialty orthopedic shoes prescribed for plantar fasciitis, diabetic foot care, or post-surgical recovery are eligible with an LMN.
Are mattresses covered?
With an LMN naming a sleep-related condition (chronic back pain, sleep apnea, fibromyalgia), yes.
Is Peloton covered?
With an LMN, yes. See our Peloton guide.
Is the LMN fee itself FSA/HSA eligible?
Yes — for the seventh time. Yes.
Get your LMN
If you've got a documented context and you're shopping for an LMN-eligible product, get the LMN first. $25 flat at Burst, full refund if our clinician declines.
If you're not sure whether your situation fits, hit reply on any Burst email or write to support@getburst.com. We read every email ourselves.
Thanks,
Shubhi
Co-Founder at Burst
For the underlying rules, see IRS Publication 502, IRS Notice 2006-69, and IRS Notice 2007-2.
Last updated: May 2026
This guide is not medical advice. Your eligibility depends on your specific situation and your plan administrator's interpretation of IRS rules. Burst's clinicians make eligibility decisions on a case-by-case basis.
