Quick Answer: A Letter of Medical Necessity (LMN) is a short document from a licensed healthcare provider that says a product or service is medically necessary for you. It's what makes wellness products like gym memberships, fitness trackers, and supplements eligible for HSA/FSA coverage.
Think of It Like a Medical Authorization
You know how you sometimes need a letter from your doctor to verify something medical? An LMN works similarly — it tells your HSA/FSA admin that a purchase is a legitimate medical expense.
The IRS recognizes that many wellness products can serve both personal and medical purposes. A gym membership could be for fun - or it could be part of managing your blood pressure. An LMN is what makes the difference.
Why Do I Need One?
Under IRS rules, certain products are only HSA/FSA eligible when they're connected to a specific health need. The IRS calls these "dual-purpose items" - things that could be for general wellness OR for treating a medical condition.
Without an LMN, your HSA/FSA admin has no way to know if you're buying a gym membership for fun or because your doctor says you need regular exercise to manage your Type 2 diabetes.
Products that typically require an LMN include: - Gym memberships and fitness classes - Fitness trackers and smartwatches (Apple Watch, Oura Ring, WHOOP) - Vitamins and supplements - Recovery tools (massage devices, saunas, cold plunges) - Sleep technology (Eight Sleep, sleep trackers) - Home fitness equipment (Peloton, Tonal) - Red light therapy devices - Air purifiers (for respiratory conditions)
Products that DON'T need an LMN: - Prescription medications - Over-the-counter medicines (Advil, Claritin, etc.) - Sunscreen (SPF 15+) - First aid supplies - Menstrual care products - Contact lenses and glasses
What's In an LMN?
A typical LMN from Crates includes:
Your information - Name and eligibility details
A medical diagnosis - Your specific condition, often with an ICD-10 code (the standardized medical classification code)
Treatment recommendation - The specific product being recommended, written by a licensed healthcare provider
Medical necessity statement - How the product helps prevent, manage, or reverse your condition
Duration - How long the treatment plan covers
Provider signature - From the licensed healthcare professional who reviewed your case
Do I Need to Be Sick to Get an LMN?
No! You don't need to have a serious illness. Many common health concerns qualify, including:
High blood pressure or family history of heart disease
Being overweight or having a BMI over 25
Pre-diabetes or Type 2 diabetes
Anxiety, depression, or chronic stress
Chronic back pain or joint issues
Sleep problems or insomnia
High cholesterol
ADHD
Even prevention can qualify. If you have risk factors for a condition, an LMN can document that a wellness product helps prevent it.
How Do I Get an LMN?
With Crates Health, you don't need to visit a doctor or schedule an appointment:
Sign up at crateshealth.com and choose your plan
Complete a health assessment (about 2-3 minutes)
Select the products you want to cover
Our licensed healthcare providers review your case and issue your LMN — many in just minutes for catalog products
That's it. No office visits. No copays. No waiting weeks for an appointment.
How Long Is My LMN Valid?
LMNs are typically valid for 12 months. After that, you'll need a renewal - Crates handles renewals automatically for active subscribers.
Can My Regular Doctor Write an LMN Instead?
Absolutely! Any licensed healthcare provider (MD, DO, NP, PA) can write an LMN. If you prefer to go through your doctor, you're welcome to do so. Some things to know:
Your doctor may charge for the visit ($50-150+ copay)
It may take 1-4 weeks to get your appointment and letter
Make sure the letter includes all the required components listed above
Many customers choose Crates because it's faster and more affordable than going through their doctor, but either path works.
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