HSA/FSA for a Sauna: Letter of Medical Necessity

Sauna stores now print "HSA/FSA eligible" next to the price. That label is doing a lot of work. The IRS does not approve products. It approves reasons. A sauna bought to treat a diagnosed condition can be a medical expense. The same sauna bought because it feels good is not, no matter what the checkout page says.

This guide is written from the IRS's own publications, not from a seller's FAQ. It is not tax advice. Your plan administrator and a tax advisor have the final word on your situation.

What this guide covers:

• What the IRS actually counts as medical care, and what it rules out
• How HSA and FSA claims get checked, and by whom
• The letter of medical necessity, step by step
• The home-improvement math for built-in and outdoor saunas
• What it saves in real dollars, and what it costs if the claim fails
• What "HSA/FSA eligible" means on a sauna store

The Short Answer: The Reason Qualifies, Not the Sauna

There is no IRS list of eligible saunas. We searched IRS Publication 502 (medical expenses), Publication 969 (HSAs and FSAs) and the IRS's FAQ on wellness expenses for the word "sauna" and found nothing. What those documents do contain is a test, and the test is about you, not the product.

Publication 502 says medical care expenses "must be primarily to alleviate or prevent a physical or mental disability or illness. They don't include expenses that are merely beneficial to general health, such as vitamins or a vacation."

So the real question is not "is this sauna HSA eligible?" It is "would I be buying this sauna primarily to treat a condition a clinician has diagnosed?" If the answer is yes, a letter of medical necessity (LMN) is how you document it. If the answer is "it would be good for me in general," the expense does not qualify, and a letter does not fix that.

What the IRS Actually Counts as Medical Care

The IRS wellness FAQ is the closest thing to a rulebook for dual-purpose purchases, things that have both a medical use and an everyday use. Three of its answers map directly onto a sauna:

The IRS made the point bluntly in a March 2024 alert, IR-2024-65. It warned that some companies "mistakenly claim that notes from doctors based merely on self-reported health information can convert non-medical food, wellness and exercise expenses into medical expenses, but this documentation actually doesn't." The release does not mention saunas. It is about the business model: paperwork sold alongside a wellness product.

Two more Publication 502 rules matter. You cannot count an expense your HSA already paid for. And if you go the tax-deduction route instead of an account, you can only deduct medical expenses above 7.5% of your adjusted gross income. For a household with $150,000 of AGI, the first $11,250 of medical costs that year does not count, and you have to itemize.

HSA vs FSA: Who Checks Your Claim

The same IRS definition applies to both accounts. What differs is when someone checks.

FSA: the administrator checks before paying. Publication 969 says you must give the FSA "a written statement from an independent third party stating that the medical expense has been incurred and the amount," plus a statement that no other plan paid it. For a sauna, expect the administrator to ask for an itemized receipt and the LMN. They can say no. In the IRS's own example in IR-2024-65, a buyer submits a purchased doctor's note to his FSA and "the claim is denied because food is not a medical expense and plan administrators are wary of claims that could invalidate their plans." That wariness is rational: the release says a plan that reimburses non-medical expenses is not a qualified plan, and then all its payments become taxable income.

HSA: nobody checks up front, so you carry the risk. Your HSA custodian reports what you withdraw on Form 1099-SA. You report it on Form 8889. Publication 969 puts the proof on you: you "must keep records sufficient to show that the distributions were exclusively to pay or reimburse qualified medical expenses." You don't send those records with your return. You produce them if asked.

Contribution limits cap what either account can cover. For 2026, the health FSA limit is $3,400 per employee (Rev. Proc. 2025-32). The HSA limit is $4,400 for self-only coverage and $8,750 for family coverage (Publication 969). A $6,000 sauna can exceed one year of FSA money on its own.

Two timing details buyers miss:

• FSA: Publication 969 says you must be able to receive your full annual election at any time during the coverage period, even if you have not contributed it yet. If your employer allows it, you can elect $3,400 in January and claim it in February.
• HSA: You can pay out of pocket now and reimburse yourself later, as long as the expense came after you opened the HSA. Publication 969 says expenses incurred before the HSA was established don't qualify, and you don't have to withdraw in the same year.

How the Letter of Medical Necessity Process Works

An LMN is a short letter from a licensed clinician tying a specific purchase to a specific diagnosis. Here is the process in the order that protects you.

1. Call your plan before you shop. Ask your FSA administrator or HSA custodian three things: Do you require an LMN for a sauna? Do you have your own form? Will you review it before I buy? Some administrators publish their own LMN form. WEX, a large benefits administrator, tells account holders to "check with your account provider to see if an LMN is required" before purchasing.

2. Start with the diagnosis, not the sauna. The letter only works if there is a real condition and a clinician who believes heat therapy treats it. If you have a heart condition, take medication that affects heat tolerance, or are pregnant, this is also the conversation where you ask whether sauna use is safe for you. Our guide to who should not use a sauna lists the questions worth bringing.

3. Make sure the letter has what administrators look for. WEX's checklist says an LMN should include your name and diagnosis, the recommended treatment or item, a statement of why it is medically necessary, the provider's name, credentials and signature, and the date. WEX also notes that most LMNs are valid for one year, and some plans require renewal sooner.

4. Pay in a way your plan accepts. Either pay with your HSA or FSA card, or pay normally and submit the receipt and LMN for reimbursement. Keep the itemized receipt. An FSA needs a written third-party statement of what was bought and for how much, and the receipt is that statement.

5. Keep the file for as long as you keep tax records. Receipt, letter, delivery confirmation, and any notes from your clinician. If you ever need to show the purchase was medical, this file is the whole case.

What a checkout LMN service does

At least two brands we cover, Sunlighten and Almost Heaven, route HSA and FSA payments through Truemed. Truemed's own page describes the flow: pick Truemed at checkout, complete a health survey, and "an independent licensed healthcare provider reviews each case." If you qualify, you get an LMN and pay with your HSA or FSA card in one step. If the store does not offer Truemed at checkout, you pay normally and submit the letter to your administrator. Truemed's page states that "qualification isn't guaranteed for every customer or every purchase." Almost Heaven's Truemed page says the service is "no cost to you, as long as you are shopping with a Truemed partner merchant."

That last line is worth thinking about. The letter is part of the store's checkout. The buyer does not pay for it. That does not make the letter invalid. It does mean the paperwork comes from a service built into the store that is selling you the sauna. IR-2024-65 was aimed at a related setup: notes sold alongside wellness products that rest "merely on self-reported health information." Truemed says a licensed provider reviews each case, and we have not seen its review process from the inside. What we can say is that a letter from a clinician who diagnosed and treats your condition is a different document from a survey answered at checkout. Your administrator, and in an HSA audit the IRS, decides how much weight either one carries.

Built-In and Outdoor Saunas: The Home-Improvement Math

Publication 502 has a separate rule for "special equipment installed in a home or for improvements" whose main purpose is medical care. If the improvement raises your home's value, only the part of the cost above that increase counts as a medical expense. The IRS gives a worksheet (Worksheet A): what you paid, minus the increase in your home's value from before to after the improvement. If the value increase is equal to or more than what you paid, nothing counts.

Here is what that looks like on a sauna. Our home value guide puts a well-installed sauna at roughly 1% to 3% of appraised value. That is our estimate from real estate sources, not an appraisal of your house.

The IRS wants the value "immediately before" and "immediately after" the improvement, which in practice means an appraisal, not a guess. And all of this still depends on the main purpose being medical.

Two more points from Publication 502:

• Running costs can count. "Amounts you pay for operation and upkeep of a capital asset qualify as medical expenses as long as the main reason for them is medical care," even if only part of the original cost qualified. Our running-cost guide estimates what a sauna adds to the electric bill.
• Aesthetic upgrades don't. For accessibility improvements, the publication says "additional costs for personal motives, such as for architectural or aesthetic reasons, aren't medical expenses." A cedar upgrade or a panoramic window is not part of the treatment.

Whether a freestanding plug-in infrared cabin is "equipment" or a permanent "improvement" is not something Publication 502 answers for saunas. Ask a tax advisor before you count on the full price.

What It Saves in Real Dollars

The savings come from paying with money that was never taxed. How much depends on your bracket and how the money got into the account. The example uses a $6,000 two-person infrared cabin; the five two-person models in our infrared brands comparison listed at $5,599 to $7,499 in October 2026. Our cost guide covers the electrical work and delivery on top.

Federal brackets are from Rev. Proc. 2025-32: for 2026, the 22% bracket covers taxable income from $100,800 to $211,400 for married couples filing jointly ($50,400 to $105,700 single). Payroll tax is the 6.2% Social Security plus 1.45% Medicare employee share, 7.65% total (IRS Topic 751). Money that goes into an HSA through an employer's cafeteria plan is treated as an employer contribution and is generally not subject to employment taxes (Publication 969). Health FSA salary reductions skip both income and employment taxes.

The HSA rows assume the money is already in the account. With self-only coverage you can only put in $4,400 for 2026, so paying the whole $6,000 from an HSA takes family coverage or a balance saved from earlier years. State income tax can add more, depending on where you live. Social Security tax stops above that year's wage base, so very high earners save less than the 7.65% line suggests.

That top line matches the "about 30%" figure sauna stores advertise: 22% plus 7.65% is 29.65%. At the 12% bracket, it is closer to 20%. With an FSA, the cap means you save on $3,400, not on the whole sauna.

What It Costs If the Claim Does Not Hold

FSA denial: The administrator does not reimburse you. You paid for the sauna with after-tax money, the same as any buyer without an account. Annoying, but you know right away.

HSA disallowed later: This is the expensive one. Publication 969 says a distribution not used for qualified medical expenses is taxable, and "there is an additional 20% tax on the part of your distributions not used for qualified medical expenses." That additional tax does not apply after you are disabled, reach 65, or die.

Using the same $6,000 sauna at the 22% bracket, if the IRS decides it was not a medical expense:

That is more than the $1,779 the HSA route was supposed to save. Before you pay, ask yourself whether you could explain to an auditor, with your file in hand, why the sauna was primarily medical. If you can't, pay with regular money and keep your HSA for what it is built for.

What "HSA/FSA Eligible" Means on a Sauna Store

It means the store has a payment route for HSA and FSA cards, usually through an LMN service. It does not mean the IRS has reviewed the product, and it does not mean your plan will accept the claim. Here is how two brands we cover describe it, checked October 25, 2026.

Sunlighten headlines its page "save up to 30% with pre-tax dollars," says it partners with Truemed, and states that "saunas have always been eligible for reimbursement." The same site's disclaimer says Sunlighten products "are considered General Wellness products, not medical devices, as defined by the Food and Drug Administration. They are not intended to treat, cure or prevent diseases or medical conditions." Both statements can be true at once, but they point in different directions. Eligibility comes from your diagnosis and your plan, not from the product. If you are pricing Sunlighten, our Sunlighten price check has the current cabin prices.

Almost Heaven offers Truemed at checkout and advertises "net savings of ~30%," with a footnote: "On average, 30% of gross income is paid to state and federal tax. Individual tax rates vary." As the table above shows, your actual savings depend on your marginal bracket, how you funded the account, and your FSA cap.

Neither page is wrong to offer the option. Just read "eligible" as "payable with an HSA card if you qualify," and do the qualifying part yourself.

A Five-Minute Checklist Before You Pay

• I have a diagnosed condition, and my clinician recommends heat therapy as treatment for it, not for general health.
• I asked my FSA administrator or HSA custodian whether they need an LMN and whether they have their own form.
• The LMN names my diagnosis, the sauna, why it is necessary, the provider's credentials and signature, and the date.
• I checked how much of the price my 2026 limit actually covers ($3,400 FSA; $4,400 or $8,750 HSA).
• For a built-in or outdoor sauna, I asked a tax advisor about the home-improvement rule before counting the full cost.
• I have a folder with the itemized receipt, the letter and the delivery confirmation.
• I compared the sauna price itself with our quote checklist, so pre-tax money is not paying for padding.

What We Could Not Verify

• Any IRS ruling or publication that names saunas. We found none in Publication 502, Publication 969 or the IRS wellness FAQ. The analogies above (gym memberships, exercise, wearables) are our reading of how the same test applies.
• How often sauna LMN claims are approved or denied. No administrator or LMN service we found publishes approval rates for saunas.
• Which medical conditions justify a sauna. The IRS does not publish a list, and that is a clinical judgment for your doctor, not for a sauna store or for us.
• What LMN services pay or charge merchants. Almost Heaven says the service costs the buyer nothing at a partner merchant. We did not find published merchant pricing.

Frequently Asked Questions

Can I use my HSA for a sauna?

Only if the sauna is primarily for medical care, meaning it treats or prevents a specific condition a clinician has diagnosed. IRS Publication 502 excludes expenses that are "merely beneficial to general health." Get a letter of medical necessity, keep the receipt and the letter, and know that nobody approves an HSA purchase up front. If the IRS later disallows it, you owe income tax plus a 20% additional tax if you are under 65.

Is an infrared sauna FSA eligible?

Infrared or traditional makes no difference to the IRS. What matters is whether you are buying it to treat a diagnosed condition. Your FSA administrator will usually want an itemized receipt and a letter of medical necessity, and it can still deny the claim. The 2026 FSA limit is $3,400 per employee, so it rarely covers a full cabin.

How do I get a letter of medical necessity for a sauna?

Start with your own clinician and the condition they treat, not with the sauna. If they believe heat therapy is a treatment for it, ask for a letter that names your diagnosis, the sauna, why it is necessary, their credentials and signature, and the date. Check first whether your plan has its own LMN form. Some sauna stores offer a checkout service, such as Truemed, that issues letters after an online health survey and a provider review.

Does a letter of medical necessity guarantee my claim will be approved?

No. The letter documents your medical reason. Your FSA administrator decides whether to reimburse, and for an HSA the IRS can question the expense later. In its 2024 alert, the IRS said doctors' notes based merely on self-reported health information do not turn personal wellness expenses into medical expenses. Truemed's own page says qualification is not guaranteed.

Can I deduct a home sauna on my taxes as a medical expense?

Possibly, under the same "primarily for medical care" test, but only the part of your total medical expenses above 7.5% of your adjusted gross income, and only if you itemize. For a permanent installation that raises your home's value, Publication 502 only counts the cost above that increase. You cannot deduct anything you already paid with HSA money.

What happens if the IRS says my sauna wasn't a medical expense?

With an HSA, the withdrawal becomes taxable income, plus a 20% additional tax unless you were 65 or older, or disabled. On a $6,000 sauna at the 22% bracket, that is about $2,520. With an FSA, the usual outcome is simpler: the administrator refuses to reimburse, and you pay with after-tax money.

Sources

• IRS Publication 502 (2025), Medical and Dental Expenses - definition of medical care, general-health exclusion, capital expenses and Worksheet A, operation and upkeep, 7.5% AGI floor. Checked 2026-10-25
• IRS Publication 969 (2025), Health Savings Accounts and Other Tax-Favored Health Plans - HSA recordkeeping, 20% additional tax, 2026 HSA limits, FSA substantiation, cafeteria plan contributions. Checked 2026-10-25
• IRS FAQ: Medical expenses related to nutrition, wellness and general health - Q10, Q11 and Q15 (wearables, added September 23, 2026). Checked 2026-10-25
• IRS IR-2024-65: Beware of companies misrepresenting nutrition, wellness and general health expenses as medical care - March 6, 2024. Checked 2026-10-25
• IRS Revenue Procedure 2025-32 - 2026 tax brackets and the $3,400 health FSA limit. Checked 2026-10-25
• IRS Topic 751, Social Security and Medicare withholding rates - 6.2% and 1.45% employee rates. Checked 2026-10-25
• WEX: What is a letter of medical necessity and when do you need one? - LMN contents and validity. Checked 2026-10-25
• Truemed: How it works - checkout LMN process and qualification disclaimer. Checked 2026-10-25
• Sunlighten: HSA/FSA - Truemed partnership, savings claim and general wellness disclaimer. Checked 2026-10-25
• Almost Heaven: How to check out with HSA/FSA funds - Truemed checkout and ~30% savings footnote. Checked 2026-10-25