HSA/FSA

3 Easiest Ways To Get a Letter of Medical Necessity Online

Find out how to get a Letter of Medical Necessity (LMN) online, including the three main methods to do it and how to check if it’s a legitimate provider.

December 2, 2025

Teddy Butz
Director of Product & Partner Marketing

Overview

Overview

Overview

A Letter of Medical Necessity (LMN) can qualify certain medical expenses to be covered by your HSA/FSA. But when you want to purchase something online quickly, you don’t have time to wait to get an appointment with your doctor. Fortunately, there are ways to get an LMN online, and we’ll show you how:

Let’s start with the basics, like what makes an online LMN unique from a traditional one, how to check a letter is legitimate, and the main components to look for in a letter.


Important things to know before trying to get a LMN online

A Letter of Medical Necessity (LMN) you get online is very similar to the one you’d get at a doctor’s office, it’s just a much faster, easier process. It really just comes down to finding the most convenient option for you, while ensuring they’re a legitimate provider.

What makes an online Letter of Medical Necessity different from a regular one?

An online Letter of Medical Necessity (LMN) is functionally the same as a traditional one. The only difference is the entire process is done online, including the consultation.

The rise in popularity of both online healthcare and telehealth has made this far more accessible in recent years. You no longer have to visit your doctor in person, but can instead complete a quick consultation at checkout, receiving an LMN for your medically approved purchase in less than a minute.

How do you know if an online Letter of Medical Necessity you get is legitimate?

The best way to verify that a Letter of Medical Necessity you received online is legitimate is to check the source of the letter and the credentials of the healthcare provider. Importantly, the letter must come from a licensed healthcare provider that has completed a genuine medical assessment.

The first thing to look for is the healthcare professional’s credentials, including their name, official title, and contact details. Ideally, they’ve also listed their license number and the jurisdiction they’re licensed to operate in. They should also have officially signed the document.

Next, the letter should include the patient details, as it should be addressed to a specific individual for a particular health issue. It should also include the date it was written, as a Letter of Medical Necessity is typically valid for 12 months. 

If any of this information is missing, it could be a sign you’re not dealing with a legitimate provider. Here are some other red flags to look for:

  1. No consultation required: While you don’t have to see a doctor in person, you will need a consultation of some kind (online or over the phone) to have a Letter of Medical Necessity issued.

  2. Guaranteed approval: A provider guarantees they can provide you an LMN without hearing your circumstances.

  3. Instant turnaround: Getting an LMN should always require a consultation—it can be fast (like 5 minutes), but it should never be instantaneous.

  4. Generic information: If the details of the letter are generic or vague, then it likely wasn’t written for you.

  5. Missing contact info: The details or contact information for either the healthcare provider or LMN provider is ambiguous (or outright missing).

  6. Requesting sensitive information not related to your health: The LMN provider shouldn’t request sensitive personal information like your Social Security Number or passwords.

If the letter you get back doesn’t speak directly to your situation and doesn’t have all the credentials that show a genuine assessment was conducted by a healthcare professional, then it may not be a legitimate LMN.

5 necessary components an online Letter of Medical Necessity should include

When you get your letter, you’ll want to check that it has the following elements before you pass it off to your provider.

  1. Patient details - The letter should contain personal information like your name and date of birth. In some cases, it may have other information like your address or policy number.

  2. Clearly state your medical diagnosis - State exactly what the medical condition is. It doesn’t hurt to have some details about your medical history pertaining to the condition, such as when you were first diagnosed, how your condition has changed, and what treatments you’ve tried in the past.

  3. Define your treatment plan - Be as specific as possible about the particular products or services that would be helpful in executing the patient’s treatment plan.

  4. Justification of medical necessity - Clearly state why the recommended product or service is a medical necessity, connecting it with the treatment plan, explaining exactly how this will help the patient fix,  manage, or alleviate their condition.

  5. Signature & credentials - The healthcare professional that administered the letter should provide their credentials, including their name, title, and license number. They should also sign the letter to make it official.

Template letter for a Letter of Medical Necessity


3 ways to get a Letter of Medical Necessity online

Getting a Letter of Medical Necessity online is very simple if you do it the right way. Here are the three main ways to do it.

1. Directly at checkout when shopping for HSA/FSA-eligible items

Start an online consultation easily and quickly

The fastest and easiest way to get a Letter of Medical Necessity is to do it directly at checkout with a tool like Flex. We integrate directly into checkout, functioning much like any other payment option, and you can pay directly from your HSA/FSA account. When checking out, you complete your consultation, your LMN is issued before you make the purchase, and the LMN is emailed to you within 24 hours.

This way, the letter you get is suited to the product or service you're purchasing, and will directly connect that to your medical condition. This greatly increases the chances of the expense being approved by your provider.

Check out our Flex Shop for products and services that are eligible to be purchased through your HSA/FSA. We make it easy to buy leading brands like Therabody, Alo Wellness Club, Oura Ring, Forme, Shiseido, and Dermstore. With Flex, you can sort this all out quickly and conveniently at checkout.

2. Go to an online LMN provider or telehealth service

An online LMN provider or telehealth service will have a medical practitioner do a virtual consultation with you, via a video call, phone call, or virtual chat. The healthcare professional will assess your case, and then produce a Letter of Medical Necessity according to your situation. They’ll email the LMN directly to you, making it extremely easy for you to actually get it.

3. Contact your doctor directly if they have an online portal for LMNs

Another way to get a Letter of Medical Necessity is to contact your doctor directly. To do this online, you’d most likely be emailing them. In some cases, your doctor may have an online portal you can use to sign in and conduct a consultation.

The pros are that you know the letter is authentic and your doctor already knows your medical history, so they’re in a good position to explain your situation and define why a certain type of care is justified. However, this is often a lot more time consuming than alternatives, as you’ll have to wait to get in touch with your doctor before you can finish a consultation and get your letter. This will be a decent amount of back-and-forth, so this will never be the fastest option.


Popular products and services you can buy with an online LMN

The truth is, a lot more products are eligible to be purchased using your HSA/FSA than you may think. Looking to see what you might be HSA/FSA-eligible with a Letter of Medical Necessity?

We’ve got a list of some of the most popular products based on their category:

Fitness, exercise, & workout apps

  • iFit - Attachable device for exercise equipment

  • PowerBlock - Adjustable dumbbells for at-home workouts

  • Tempo - An AI-powered virtual personal trainer on your phone

  • YourReformer - A studio-experience Pilates machine for at home workouts

  • FitBod - Customized workout app with detailed training programs

Nutrition & supplements

  • CalmiGo - An anxiety-reducing, drug-free exhaler that helps calm and sooth

  • Wellspring Meds - Reliable source for over-the-counter medication at wholesale prices

  • AND/life - A wellness program with guided workouts and meal management

  • Rootless - A daily bite that provides essential nutrients that support hormones and gut health

  • Saltivate - An electrolyte powder that maximizes hydration with no sugar

Sleep & home wellness

  • Ozlo Sleep - Noise cancelling earbuds that block out disruptions

  • SleepMe - Temperature-controlled sleep systems for your bed

  • BedJet - Bed heating and cooling device for temperature control

  • Pulsetto - Vague nerve stimulator that reduces stress and improves sleep

  • HostageTape - Mouth tape and nose strips that reduce snoring

Clothing & footwear

  • Forme - Posture-correcting athletic wear and clothing

  • Oya - Eco-conscious apparel that’s built to wick away moisture and sweat

  • Andiem - Athletic footwear designed to prevent ankle injuries

  • FitMyFoot - Personalized footwear solutions built for comfort and performance

  • Ribcap - Providing a fashionable alternative to protective headgear

Mom, baby, and child


How to get a Letter of Medical Necessity online with Flex at checkout

We make it extremely easy to get a Letter of Medical Necessity by offering a consultation at checkout for products you are already purchasing. We ask questions about the item you’re looking for so the letter you get is designed for your specific conditions and the product or service you’re looking for.

1. Find an FSA/HSA eligible item on the Flex Shop

The Flex shop marketplace

First, search our HSA/FSA-eligible marketplace for health products that you can get covered by your plan. 

2. Browse their website for the product or service you want

The Forme Science shop

Next, head to their website to browse the list of products they have. Remember, you’ll want to make sure you stick to products that are suited to your medical condition, but this allows you to check out their collection of products so you can find the ideal fit for you.

3. Choose “Flex - Pay with HSA/FSA” when you checkout

The Forme checkout using Flex

All you have to do is make sure you select Flex as your payment option during checkout, the same way you choose a credit card, PayPal, or any other payment method.

4. Go through the online Letter of Medical Necessity consultation

An online medical consultation using Flex

After selecting Flex, you’ll be automatically taken to a digital consultation with a healthcare practitioner. All you need to do is answer the questions as you’re prompted, and they will review your case.

5. Checkout as usual with your HSA/FSA card

Now you can checkout as you normally would, using your HSA/FSA card to pay directly using plan funds. You’ll get the Letter of Medical Necessity in your inbox within 24 hours, which you’ll want to keep on hand for your records.



Getting a Letter of Medical Necessity online isn’t actually all that different from getting one normally–the process is just entirely digital. You complete your consultation online and get your letter via an email, without ever having to visit a doctor in person. This also makes it very easy for you to submit it to your HSA/FSA provider for approval.

It’s crucial that you source your letter from a legitimate service, as it needs to be administered by a healthcare professional. With Flex, you can get approved for a variety of products that are advantageous to your health and easily get a Letter of Medical Necessity when you need one.

Check out the Flex Shop to find items that you may need, like a fitness studio experience from Alo Wellness Club, sunscreen from SunShield+, or evolutionary wearable tech like the Oura Ring!


A Letter of Medical Necessity (LMN) can qualify certain medical expenses to be covered by your HSA/FSA. But when you want to purchase something online quickly, you don’t have time to wait to get an appointment with your doctor. Fortunately, there are ways to get an LMN online, and we’ll show you how:

Let’s start with the basics, like what makes an online LMN unique from a traditional one, how to check a letter is legitimate, and the main components to look for in a letter.


Important things to know before trying to get a LMN online

A Letter of Medical Necessity (LMN) you get online is very similar to the one you’d get at a doctor’s office, it’s just a much faster, easier process. It really just comes down to finding the most convenient option for you, while ensuring they’re a legitimate provider.

What makes an online Letter of Medical Necessity different from a regular one?

An online Letter of Medical Necessity (LMN) is functionally the same as a traditional one. The only difference is the entire process is done online, including the consultation.

The rise in popularity of both online healthcare and telehealth has made this far more accessible in recent years. You no longer have to visit your doctor in person, but can instead complete a quick consultation at checkout, receiving an LMN for your medically approved purchase in less than a minute.

How do you know if an online Letter of Medical Necessity you get is legitimate?

The best way to verify that a Letter of Medical Necessity you received online is legitimate is to check the source of the letter and the credentials of the healthcare provider. Importantly, the letter must come from a licensed healthcare provider that has completed a genuine medical assessment.

The first thing to look for is the healthcare professional’s credentials, including their name, official title, and contact details. Ideally, they’ve also listed their license number and the jurisdiction they’re licensed to operate in. They should also have officially signed the document.

Next, the letter should include the patient details, as it should be addressed to a specific individual for a particular health issue. It should also include the date it was written, as a Letter of Medical Necessity is typically valid for 12 months. 

If any of this information is missing, it could be a sign you’re not dealing with a legitimate provider. Here are some other red flags to look for:

  1. No consultation required: While you don’t have to see a doctor in person, you will need a consultation of some kind (online or over the phone) to have a Letter of Medical Necessity issued.

  2. Guaranteed approval: A provider guarantees they can provide you an LMN without hearing your circumstances.

  3. Instant turnaround: Getting an LMN should always require a consultation—it can be fast (like 5 minutes), but it should never be instantaneous.

  4. Generic information: If the details of the letter are generic or vague, then it likely wasn’t written for you.

  5. Missing contact info: The details or contact information for either the healthcare provider or LMN provider is ambiguous (or outright missing).

  6. Requesting sensitive information not related to your health: The LMN provider shouldn’t request sensitive personal information like your Social Security Number or passwords.

If the letter you get back doesn’t speak directly to your situation and doesn’t have all the credentials that show a genuine assessment was conducted by a healthcare professional, then it may not be a legitimate LMN.

5 necessary components an online Letter of Medical Necessity should include

When you get your letter, you’ll want to check that it has the following elements before you pass it off to your provider.

  1. Patient details - The letter should contain personal information like your name and date of birth. In some cases, it may have other information like your address or policy number.

  2. Clearly state your medical diagnosis - State exactly what the medical condition is. It doesn’t hurt to have some details about your medical history pertaining to the condition, such as when you were first diagnosed, how your condition has changed, and what treatments you’ve tried in the past.

  3. Define your treatment plan - Be as specific as possible about the particular products or services that would be helpful in executing the patient’s treatment plan.

  4. Justification of medical necessity - Clearly state why the recommended product or service is a medical necessity, connecting it with the treatment plan, explaining exactly how this will help the patient fix,  manage, or alleviate their condition.

  5. Signature & credentials - The healthcare professional that administered the letter should provide their credentials, including their name, title, and license number. They should also sign the letter to make it official.

Template letter for a Letter of Medical Necessity


3 ways to get a Letter of Medical Necessity online

Getting a Letter of Medical Necessity online is very simple if you do it the right way. Here are the three main ways to do it.

1. Directly at checkout when shopping for HSA/FSA-eligible items

Start an online consultation easily and quickly

The fastest and easiest way to get a Letter of Medical Necessity is to do it directly at checkout with a tool like Flex. We integrate directly into checkout, functioning much like any other payment option, and you can pay directly from your HSA/FSA account. When checking out, you complete your consultation, your LMN is issued before you make the purchase, and the LMN is emailed to you within 24 hours.

This way, the letter you get is suited to the product or service you're purchasing, and will directly connect that to your medical condition. This greatly increases the chances of the expense being approved by your provider.

Check out our Flex Shop for products and services that are eligible to be purchased through your HSA/FSA. We make it easy to buy leading brands like Therabody, Alo Wellness Club, Oura Ring, Forme, Shiseido, and Dermstore. With Flex, you can sort this all out quickly and conveniently at checkout.

2. Go to an online LMN provider or telehealth service

An online LMN provider or telehealth service will have a medical practitioner do a virtual consultation with you, via a video call, phone call, or virtual chat. The healthcare professional will assess your case, and then produce a Letter of Medical Necessity according to your situation. They’ll email the LMN directly to you, making it extremely easy for you to actually get it.

3. Contact your doctor directly if they have an online portal for LMNs

Another way to get a Letter of Medical Necessity is to contact your doctor directly. To do this online, you’d most likely be emailing them. In some cases, your doctor may have an online portal you can use to sign in and conduct a consultation.

The pros are that you know the letter is authentic and your doctor already knows your medical history, so they’re in a good position to explain your situation and define why a certain type of care is justified. However, this is often a lot more time consuming than alternatives, as you’ll have to wait to get in touch with your doctor before you can finish a consultation and get your letter. This will be a decent amount of back-and-forth, so this will never be the fastest option.


Popular products and services you can buy with an online LMN

The truth is, a lot more products are eligible to be purchased using your HSA/FSA than you may think. Looking to see what you might be HSA/FSA-eligible with a Letter of Medical Necessity?

We’ve got a list of some of the most popular products based on their category:

Fitness, exercise, & workout apps

  • iFit - Attachable device for exercise equipment

  • PowerBlock - Adjustable dumbbells for at-home workouts

  • Tempo - An AI-powered virtual personal trainer on your phone

  • YourReformer - A studio-experience Pilates machine for at home workouts

  • FitBod - Customized workout app with detailed training programs

Nutrition & supplements

  • CalmiGo - An anxiety-reducing, drug-free exhaler that helps calm and sooth

  • Wellspring Meds - Reliable source for over-the-counter medication at wholesale prices

  • AND/life - A wellness program with guided workouts and meal management

  • Rootless - A daily bite that provides essential nutrients that support hormones and gut health

  • Saltivate - An electrolyte powder that maximizes hydration with no sugar

Sleep & home wellness

  • Ozlo Sleep - Noise cancelling earbuds that block out disruptions

  • SleepMe - Temperature-controlled sleep systems for your bed

  • BedJet - Bed heating and cooling device for temperature control

  • Pulsetto - Vague nerve stimulator that reduces stress and improves sleep

  • HostageTape - Mouth tape and nose strips that reduce snoring

Clothing & footwear

  • Forme - Posture-correcting athletic wear and clothing

  • Oya - Eco-conscious apparel that’s built to wick away moisture and sweat

  • Andiem - Athletic footwear designed to prevent ankle injuries

  • FitMyFoot - Personalized footwear solutions built for comfort and performance

  • Ribcap - Providing a fashionable alternative to protective headgear

Mom, baby, and child


How to get a Letter of Medical Necessity online with Flex at checkout

We make it extremely easy to get a Letter of Medical Necessity by offering a consultation at checkout for products you are already purchasing. We ask questions about the item you’re looking for so the letter you get is designed for your specific conditions and the product or service you’re looking for.

1. Find an FSA/HSA eligible item on the Flex Shop

The Flex shop marketplace

First, search our HSA/FSA-eligible marketplace for health products that you can get covered by your plan. 

2. Browse their website for the product or service you want

The Forme Science shop

Next, head to their website to browse the list of products they have. Remember, you’ll want to make sure you stick to products that are suited to your medical condition, but this allows you to check out their collection of products so you can find the ideal fit for you.

3. Choose “Flex - Pay with HSA/FSA” when you checkout

The Forme checkout using Flex

All you have to do is make sure you select Flex as your payment option during checkout, the same way you choose a credit card, PayPal, or any other payment method.

4. Go through the online Letter of Medical Necessity consultation

An online medical consultation using Flex

After selecting Flex, you’ll be automatically taken to a digital consultation with a healthcare practitioner. All you need to do is answer the questions as you’re prompted, and they will review your case.

5. Checkout as usual with your HSA/FSA card

Now you can checkout as you normally would, using your HSA/FSA card to pay directly using plan funds. You’ll get the Letter of Medical Necessity in your inbox within 24 hours, which you’ll want to keep on hand for your records.



Getting a Letter of Medical Necessity online isn’t actually all that different from getting one normally–the process is just entirely digital. You complete your consultation online and get your letter via an email, without ever having to visit a doctor in person. This also makes it very easy for you to submit it to your HSA/FSA provider for approval.

It’s crucial that you source your letter from a legitimate service, as it needs to be administered by a healthcare professional. With Flex, you can get approved for a variety of products that are advantageous to your health and easily get a Letter of Medical Necessity when you need one.

Check out the Flex Shop to find items that you may need, like a fitness studio experience from Alo Wellness Club, sunscreen from SunShield+, or evolutionary wearable tech like the Oura Ring!


Flex is the easiest way for direct to consumer brands and retailers to accept HSA/FSA for their products. From fitness and nutrition, to sleep and mental health, Flex takes a holistic view of healthcare and enables consumers to use their pre-tax money to do the same.