Your HSA covers way more than you think. If you have a letter from a doctor. Here’s how to get one in 15 minutes for about $40.

Most HSA articles tell you what’s eligible (doctor visits, prescriptions, dental, vision). What they don’t tell you is the much bigger second category: items that require a letter of medical necessity to qualify. Wearables like Oura and Whoop. Gym memberships when prescribed for a medical condition. Specific supplements. Mattress wedges for sleep apnea. Air purifiers for allergies. The list runs into thousands of items.

The gatekeeper is a letter of medical necessity (LMN). And until about three years ago, getting one meant scheduling an appointment with your primary care doctor, hoping they’d write it, and waiting weeks. Now you can get one in 15 minutes through specialized telehealth services for $40 to $80. This post walks you through exactly how.

I’m Thyrza, a licensed health insurance agent. I work mostly with self-employed people and high earners who want to actually use the tax tools they’re paying for. The letter of medical necessity is the single biggest “unlock” in the HSA ecosystem, and almost nobody knows how easy it’s become to obtain one.

Quick Check: Could a Letter of Medical Necessity Save You Money?

Four yes-or-no questions.

Do you have an HSA or FSA with money in it? The LMN strategy only works if you have a tax-advantaged account to spend from. No account, no benefit.

Are you considering buying a health-related product over $200 (wearable, mattress, gym membership, etc.)? The math starts working at around $200. Below that, the cost of the LMN may outweigh the tax savings.

Do you have any documented health condition (sleep issues, anxiety, back pain, allergies, cardiovascular concerns)? The LMN has to tie the purchase to a specific medical condition. Most adults qualify for something.

Are you in a 24%+ federal bracket? The tax savings on a $1,500 Oura + Whoop combo are about $360 at the 24% bracket and $480 at the 32% bracket. Higher bracket, more upside.

Yes to three or more? Keep reading.

What a Letter of Medical Necessity Actually Is

A letter of medical necessity is a short document from a licensed healthcare provider stating that a specific product or service is medically necessary to prevent, treat, or manage a specific condition. It’s the bridge between “this is a wellness purchase” and “this is a qualified medical expense” under IRS Publication 502.

Once you have an LMN on file, the related purchase becomes HSA-eligible. You can pay for it with your HSA card or reimburse yourself later. If you get audited, the LMN is your proof that the expense was a qualified medical expense.

The 4 Telehealth Services That Write LMNs in 15 Minutes

Truemed. Partners with brands like Whoop, Eight Sleep, Therabody, and many supplements. You check out on the brand’s site, select Truemed at payment, answer a short health questionnaire, and a licensed provider issues your LMN on the spot. Cost is typically baked into the product purchase. Use this whenever you see the Truemed logo at checkout.

Steady MD. General-purpose telehealth that writes LMNs for a wider range of products. Around $40 for a single LMN consult. Good for one-off purchases that don’t have a partner program.

Sika Health. Specifically focused on HSA/FSA LMN issuance. Often integrated with brand checkouts the same way Truemed is. Strong on supplement and wearable categories.

Flex. Newer entrant with a similar model. Worth checking if Truemed or Sika don’t have your specific product covered.

The process at each service is similar. Brief intake form. Specific condition you’re managing. Specific product you want covered. Licensed provider reviews and either issues the LMN or asks a follow-up question. Total time: 5 to 20 minutes.

One thing worth noting: most of the health plans I work with offer telehealth for free already. That means getting your letter of medical necessity may cost you nothing beyond the $40 consultation — and in many cases, even less.

What Conditions and Items Actually Qualify

The IRS framework: the product must be primarily for medical care, used to alleviate or prevent a physical or mental defect or illness. That sounds narrow but in practice it’s broad. Common pairings include:

• Sleep tracking wearable (Oura, Whoop) for insomnia, sleep apnea, or sleep optimization for an existing condition
• Continuous glucose monitor (Levels, Stelo) for metabolic health or pre-diabetes management
• Gym membership when prescribed for obesity, hypertension, or cardiovascular disease
• Specific supplements for documented deficiencies (vitamin D, magnesium, omega-3 for inflammation)
• Mattress wedges or specialty pillows for sleep apnea or GERD
• Air purifiers for severe allergies or asthma
• Therapy and counseling for documented mental health conditions

What does NOT qualify: general wellness purchases with no documented medical condition. “I want to be healthier” is not enough. “I have diagnosed sleep apnea and my doctor recommends sleep tracking” is.

Sample LMN Language

A typical LMN includes:

• Patient name and date of birth
• Provider name, credentials, and license number
• Specific medical diagnosis (often by ICD-10 code)
• Specific product or service being recommended
• Statement that the product is medically necessary to prevent, treat, or manage the diagnosed condition
• Provider signature and date
• Recommended duration (often 12 months, then renewable)

You don’t need to draft this yourself. The telehealth service writes it for you. You just receive a PDF and store it with your HSA receipts.

IRS Audit Defense

If the IRS audits your HSA reimbursements, the LMN is your proof. They need to see:

• The LMN itself (dated, signed by a licensed provider)
• The purchase receipt that matches the product described in the LMN
• Both documents stored together (Google Drive folder works fine)

As long as the LMN ties to a real medical condition and a specific product, and the receipt matches, you’re protected. The 20% penalty for unqualified withdrawals doesn’t apply when you have proper documentation. For full IRS guidance, see IRS Publication 969 on HSAs.

Final Thoughts

The letter of medical necessity is the most under-used unlock in the HSA ecosystem. Most people pay for wearables, gym memberships, and supplements with after-tax dollars and never realize they could have paid pre-tax with 15 minutes of paperwork.

Combine this with the HSA receipt hoarding strategy I covered in my earlier post, and you have a complete system: pay for everything qualifying with pre-tax HSA dollars, save the receipts (including LMNs), and reimburse yourself decades later when the balance has compounded.

Let’s Find the Right Plan for You

If you’d like to explore health plan options that work alongside an HSA strategy, I’d be glad to walk through what’s available in your state. No call center. No 600-call-a-day lead vendor. Just a licensed agent who actually answers the phone.

I’m a real licensed agent. Reach out and I’ll get back to you within one business day, usually faster.

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Thyrza de Oliveira is a licensed health insurance agent. NPN: 21702538. Licensed across multiple states. Verify any agent’s license at the National Insurance Producer Registry.