How to Get a Letter of Medical Necessity (LMN) Online: A Complete Guide
If you've ever tried to use your HSA or FSA on a wellness product and been asked for more documentation, you've run into a hurdle many people hit: some plans ask for a Letter of Medical Necessity. Whether a letter is needed, and whether your plan accepts it, is up to your plan administrator.
Whether a purchase qualifies depends on your own plan and plan administrator, so check your plan documents.
Here's what an LMN is, what plans commonly ask it to contain, and three ways people get one online.
What is a Letter of Medical Necessity?
A Letter of Medical Necessity (LMN) is a signed document from a licensed healthcare provider stating that a specific product or service is recommended for the person named in the letter. Some plans ask for one when an item could be used for either general wellness or medical purposes.
Validity varies by plan. Many plans consider a letter valid for about 12 months, after which it may need to be renewed.
What an LMN commonly includes
Plans differ, but a letter commonly contains five elements. If any of these are missing, your administrator may reject it:
- Patient information: your full name and date of birth.
- Provider details: the licensed provider's name, credentials, license number, and contact information.
- Provider's assessment: the provider's own assessment (an ICD-10 code is a plus).
- Recommended product or service: the exact product or service being recommended, including duration of use where applicable.
- Rationale and signature: a brief explanation from the provider, signed and dated by the provider.
When you might need an LMN
Some plans ask for an LMN for products or services that have both medical and general wellness uses: items that aren't automatically classified as medical equipment. Common examples include certain wellness devices, ergonomic equipment, specialty nutrition, and at-home wellness technology.
If a product page mentions "HSA/FSA eligible with an LMN," that's your cue.
Three ways people get an LMN online
1. At checkout, through an integrated provider
Some retailers and plan portals offer an online telehealth review. You answer a short questionnaire, and a licensed provider decides whether to issue a letter. Whether a letter is issued is always the provider's own clinical call, not something AWA can guarantee.
2. Through a standalone telehealth LMN service
If you're buying from a retailer that doesn't offer integrated checkout, you can use a standalone telehealth service to obtain an LMN, then submit it with a reimbursement claim to your HSA/FSA administrator. Fees and turnaround vary by service.
3. Directly through your own doctor
If you already have a primary care provider, specialist, or therapist who knows your medical history, you can simply ask them whether they would write an LMN for you. Some providers do this through their patient portal. This route can take longer but is the most personalized.
Red flags to watch for
Not every LMN service is legitimate. Be cautious of any provider that:
- Issues an LMN without any medical review or questionnaire.
- Asks for payment but doesn't connect you with a licensed provider.
- Uses generic, copy-paste language that doesn't reference your specific condition.
- Won't provide the issuing provider's license number or credentials.
A real LMN is a medical document. If a service feels more like a checkbox than a consultation, your HSA/FSA administrator may reject the letter, and you'll be on the hook for the purchase.
What to do after you get your LMN
- Save a digital and printed copy. You'll need it if your administrator requests documentation later.
- Submit it with your reimbursement claim (if you didn't use an integrated checkout). Most administrators have an online upload portal.
- Track the expiration date. Many letters are valid for about 12 months; renew before it lapses if you plan to continue purchasing.
- Keep your receipts. A letter does not replace proof of purchase.
Going through your own provider? Bring the checklist from our Letter of Medical Necessity guide to your appointment. It explains when a letter is needed.
Use your HSA/FSA at American Wellness Authority
You can pay with your HSA or FSA card at checkout. Whether a purchase is approved depends on your plan, and some plans ask for an LMN. AWA doesn't write or review LMNs ourselves; that's always the provider's own clinical judgment.
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Frequently Asked Questions
How long is a Letter of Medical Necessity valid?
Validity varies by plan. Many plans consider a letter valid for about 12 months from the date of issue. If you plan to continue making purchases in the same category, you may need to renew the letter before it expires.
Can I get an LMN for any wellness product?
An LMN must explain why a specific product is recommended for you. A licensed provider will only issue one if they judge it appropriate for your situation.
Does the LMN have to come from my own doctor?
Not always. Many plans accept a letter from any licensed healthcare provider in your state, including telehealth providers. Check with your plan administrator.
What happens if my HSA/FSA administrator rejects the claim?
Request the specific reason. Rejections often happen because the letter is missing one of the commonly required elements. Ask your provider whether an updated letter is appropriate and resubmit if your plan allows it.
Can I use an LMN for past purchases?
It depends on your plan. Some plans look at the purchase date relative to the letter's stated period. Check with your administrator for specifics.
Related reading
This article is for general education and is not tax or medical advice. LMN requirements and reimbursement rules vary by plan and by provider. Confirm with your plan administrator, and check with a healthcare provider before starting a new therapy.
