Wondering how to get a letter of medical necessity to cut your bills?
A lot of people with HSAs don’t realize how much money they’re leaving on the table, just because they’re not claiming everything they can.
That’s where understanding how to get a letter of medical necessity starts to change everything, especially if you’re trying to use your HSA for items that don’t neatly fit into the “standard medical expense” box.
We talk to people every week who assume their HSA is only for doctor visits, prescriptions, or lab work. They’re surprised when they learn how many everyday health-supporting items like ergonomic equipment, air purifiers, fitness programs, or specialized therapies, can actually qualify as HSA eligible expenses with a letter of medical necessity. The key is having the right documentation written the right way, by the right provider.
Right now, knowing what you’re eligible for matters more. Out-of-pocket costs for employees keep climbing. The average deductible for employer health plans rose to $1,886 in 2025. For individuals, the average is closer to $5000.
When budgets are tight, maximizing tax-free HSA dollars is essential. A simple LMN can be the bridge between paying after-tax dollars for something helpful, and letting your HSA cover it instead.
What Is a Letter of Medical Necessity for HSA?
A letter of medical necessity sounds more formal than it really is.
At its simplest, it’s a short note from a licensed medical provider explaining that a product, therapy, or service is needed to treat a specific condition.
HSAs already cover obvious expenses like office visits, diagnostic tests, or prescriptions without any extra paperwork. Those are easy. It’s everything outside the typical “doctor’s office” category that gets tricky. Think about things that could be useful to almost anyone, like air purifiers, posture-supporting chairs, fitness programs, or certain supplements.
Those fall into a gray space. Sometimes they’re medical. Sometimes they’re not. It depends entirely on whether they’re tied to a diagnosed condition. That’s where the letter comes in.
When a provider puts your diagnosis and recommended treatment in writing, it shows the IRS that you aren’t buying an item for convenience or lifestyle reasons. You’re buying it because it supports care for a recognized health issue.
Compare Pricing on the Best HSA Plans Available
When Do You Need an HSA Letter of Medical Necessity?
Some HSA expenses are simple to classify.
Others blur the line between medical care and general comfort, and that’s where a HSA letter of medical necessity becomes essential.
Examples that typically require a letter:
- Items that improve posture or reduce strain, like standing desks or ergonomic chairs
- Air purifiers recommended for asthma or severe allergies
- Structured fitness programs prescribed for conditions such as hypertension or obesity
- Physical therapy–adjacent services like acupuncture, chiropractic care, or therapeutic massage
- Home safety modifications, including ramps or bathroom supports
- Certain specialized foods or supplements that substitute for a required medical diet
Examples that generally do not require a letter:
- Prescription medications
- Routine office visits
- Labs, imaging, and diagnostic testing
- Most preventive care
- Common over-the-counter medications, now broadly eligible after CARES Act updates
A simple letter can turn an uncertain expense into a qualified one, but it helps to know which categories regularly call for that extra documentation.
What Must Be Included in the Letter of Medical Necessity?
A letter of medical necessity only works when it explains things plainly.
Doctors don’t need to write a novel. A few clear details are all it takes. When those pieces are missing, the letter can look unfinished, and that’s usually what causes trouble later.
A practical Letter of medical necessity sample includes:
- Your name, written the way it appears in your chart
- Your diagnosis, stated in everyday language
- The item or service your provider is recommending
- A short note explaining how the item helps with the condition
- A timeframe, often a simple “needed for the next 12 months”
- A dated signature from a licensed provider, ideally on office letterhead
Some letters carry more weight because they read like something a real provider wrote about a real patient. They mention symptoms or limitations, and show how the item supports treatment. They don’t sound interchangeable with anyone else’s paperwork.
Things that tend to make a letter stronger:
- A mention of how the condition shows up day-to-day
- Noting that the item is part of a broader care plan
- Simple, steady phrasing that feels authentic
- The provider’s contact information in case questions come up
Things that weaken a letter:
- Phrases that could apply to anyone (“for general wellness,” “for comfort”)
- No diagnosis or medical explanation
- Missing dates, missing signature, or no credentials
- Language that feels copied rather than personalized
How to Get a Letter of Medical Necessity
Learning how to get a letter of medical necessity doesn’t have to be difficult.
The key is knowing what order to approach things in, and giving your doctor enough context so the request makes sense.
Step 1: Confirm the item isn’t already clearly eligible
Some expenses fit neatly into the “medical” category.
Others can be interpreted more than one way. When something falls in that middle space, that’s when a letter becomes important.
Step 2: Reach out to your provider in a normal
A portal message works for most people.
Bringing it up during an appointment works just as well. The request doesn’t need a long explanation; a simple note that you want the purchase documented for HSA purposes is usually enough to start the conversation.
Step 3: Share the practical details
Doctors write better letters when they understand what you’re asking them to sign off on.
Useful things to include:
- What the item or service actually is
- How it connects to the condition you’re treating
- Any symptoms that make the item helpful
- A short note about why it supports your care plan
Step 4: Be ready to clarify why the letter matters
Not every provider deals with HSA paperwork regularly.
A brief explanation that the IRS wants written confirmation for items that could be considered general use often clears up any hesitation.
Step 5: Check back in if things go quiet
Clinics get busy, paperwork gets buried, and messages get missed.
A short follow-up after a few days is normal. If the provider hesitates, asking whether more information or a specialist’s input would help keeps the conversation moving.
Step 6: Look over the letter once it’s finished
Make sure it actually includes the essentials: diagnosis, the recommended item, the reason it’s needed, a timeframe, and the provider’s signature.
Save a digital copy immediately. These letters tend to matter most months or years later, not the week they’re written.
Extra Tips: Use caution with quick online LMN services
Some telehealth platforms offer legitimate evaluations.
Others rely on short surveys. The difference matters, because the IRS has raised concerns about letters that don’t reflect a real assessment. If you use a telehealth option, make sure the clinician actually reviews your condition and is licensed in your state.
Tips for Success with LMNs
Most people walk into the LMN conversation expecting it to feel formal, but it rarely plays out that way.
Doctors deal with all kinds of practical requests, and this one usually lands somewhere between a medication refill and a follow-up question they’ve heard before. A little clarity goes a long way.
What tends to help in real life:
- Start with the part of your condition that actually gets in the way. The thing that makes the item useful.
- Pull up the item on your phone or jot down a quick description so they’re not guessing.
- Mention that some health-related purchases need written confirmation for HSA use. Most providers understand the general idea even if they haven’t written one recently.
- Keep the focus on the medical problem, not the price tag. Doctors react better when the need is clear instead of feeling like they’re being asked to approve a shopping list.
A few things that usually create friction:
- Trying to link the item to a condition it doesn’t really fit
- Using vague language like “this might be nice to have”
- Forgetting to save the letter once you get it, more people lose these than you’d expect
- Assuming the provider knows exactly what your HSA requires
If your regular doctor isn’t the right fit for the request, that doesn’t mean the process stops. Certain providers are simply more connected to the issue you’re trying to address.
What to Do If Your Request Is Denied
Sometimes you ask for a letter of medical necessity, and the doctor hesitates.
A provider might look at the request, pause, and say something like, “I’m not sure this fits,” or “Let me think about it.” It’s not rejection. It’s usually uncertainty.
A few reasons they might hold back:
- The item doesn’t obviously line up with the diagnosis in your chart
- They don’t see it as part of your current treatment plan
- The request feels unrelated to what they’re treating you for
- They’re cautious about writing anything that looks like financial approval instead of medical advice
Most of the time, the conversation opens up once you explain why the item matters.
But if the answer is still “no,” you’re not stuck. It might simply mean you’re asking the wrong person.
People who sometimes end up being the better fit:
- A specialist who treats the condition more directly
- A physical therapist who sees how your body responds day to day
- A nurse practitioner or PA, depending on what your HSA accepts
Some people look to telehealth next. It can work as long as the provider actually evaluates you. The IRS has grown wary of instant letters that come from a quick online quiz, so sticking with licensed clinicians who review your case properly is important.
Also, there are cases where the item truly isn’t considered medical. It’s frustrating, especially when it feels like it should count, but knowing that early saves you from using your HSA in a way that could cause issues later.
Compare Pricing on the Best HealthShare Plans Available
Using Your Letter of Medical Necessity with Your HSA
Once the letter of medical necessity is written, the rest is mostly record-keeping.
HSAs don’t usually ask you to upload anything right away; they just expect you to hold onto the paperwork in case someone ever needs to see it later. Most people create a small folder and drop everything in there so it doesn’t disappear months down the line.
A few habits make life easier:
- Keep the letter of medical necessity with the receipt for the item
- Save a quick note about when and why you bought it
- Hold onto everything for tax purposes; seven years tends to be the rule people follow
If an audit ever comes up, you want a clean trail: your diagnosis, the letter of medical necessity, and the proof of purchase. It doesn’t need to be fancy. It just needs to be there.
Empower Your Healthcare Savings
A letter of medical necessity can be a way to make sure your HSA dollars can cover the things that genuinely support your health, even when they fall outside the usual categories.
When the request is clear and tied to your condition, most providers understand what you’re asking for and can put it in writing.
In a world where deductibles keep creeping upward, using your HSA wisely matters more than ever. A little documentation can stretch those dollars further and help you avoid paying out of pocket for things that truly belong under medical care.
Want to get more out of your care? Maximize your healthcare savings with HSA for America.
Letter of Medical Necessity Frequently Asked Questions (F.A.Q.)
Q: Can I write the letter of medical necessity myself?
A: No. It has to come from a licensed medical provider. Anything self-written won’t hold up if your HSA ever asks about it.
Q: Does the provider need to be an MD?
A: Not always. Many HSA administrators will also accept a letter of medical necessity from nurse practitioners or physician assistants, as long as they’re treating the condition.
Q: Do I need a new letter of medical necessity every year?
A: In most cases, yes. Many letters are written with a “12-month” window because treatment plans change. If your condition is ongoing, renewing the letter is normal.
Q: What if I already bought the item?
A: Some providers are willing to write a letter after the fact, but not all. It depends on whether they feel comfortable confirming the medical need retroactively.
Q: Does having the letter of medical necessity guarantee the expense will qualify?
A: It helps a lot, but nothing is guaranteed. The expense still needs to fit IRS rules, and some items remain off-limits even with documentation.
Q: Can telehealth providers issue the letter of medical necessity?
A: Yes, as long as they do a real evaluation and are licensed in your state. Quick survey-style services don’t carry the same weight.
