How to Get a Letter of Medical Necessity for a Sauna or Cold Plunge

A sauna or cold plunge can qualify as an HSA or FSA expense, but because it is a piece of equipment with everyday uses, most plan administrators want a letter of medical necessity from a licensed provider first. That letter is what turns a wellness purchase into a documented medical expense. This guide explains what the letter is, what it needs to say, and the steps to get one.

What a letter of medical necessity does

A letter of medical necessity, often shortened to LMN or LOMN, is a short signed statement from a licensed healthcare provider explaining that a specific item is needed to treat, manage, or prevent a diagnosed medical condition. Health savings accounts and flexible spending accounts can reimburse qualified medical expenses, and a sauna or cold plunge sits in a gray zone the IRS calls a dual-purpose expense: something that can be for general health or for a genuine medical need. The letter is the documentation that shows your purchase falls on the medical side. It does not guarantee approval, because each plan sets its own rules, but it is almost always the deciding document. Keep the signed letter and your receipts with your tax records in case your plan or the IRS asks you to substantiate the expense.

What the letter should include

Administrators look for a few specific elements. A strong letter usually contains:

• Your name and the date.
• The provider's name, credentials, license or NPI number, and signature.
• A specific diagnosed condition, such as chronic pain, arthritis, cardiovascular risk factors, or a diagnosed recovery or circulatory condition, rather than a vague wellness goal.
• The recommended item, naming the sauna or cold plunge as the treatment.
• How the item treats or manages the condition, in one or two sentences.
• A duration or frequency of use where relevant, for example ongoing home use.

Vague letters that say only "this is good for wellness" are the ones that get rejected. Specific condition plus specific recommendation is what plans want to see.

How to get a letter of medical necessity

The process is usually straightforward:

• Talk to your provider. Bring up your condition and ask whether regular heat or cold therapy at home is a reasonable part of your care. Your physician, and in many cases a nurse practitioner, physician assistant, chiropractor, or physical therapist, can write the letter.
• Ask for the letter in writing. Request that it name the equipment and tie it to your diagnosis. Some telehealth services also issue LMNs after a consultation if you do not have a provider handy.
• Check your plan's rules first. Contact your HSA or FSA administrator and ask what they require to reimburse a sauna or cold plunge, and whether they need pre-approval.
• Keep records. Save the signed letter, your itemized receipt, and proof of payment together.

Letters are commonly treated as valid for about a year, so you may need to renew it for ongoing or future reimbursements. Confirm the timeframe with your plan.

Sauna and cold plunge HSA/FSA eligibility at a glance

The table below summarizes how the pieces fit together. It is general information, not tax or medical advice.

Question	General answer
Is a sauna HSA/FSA eligible?	Often, with a letter of medical necessity tied to a diagnosed condition.
Is a cold plunge eligible?	Same rule; a letter is typically required for a dual-purpose item.
Who can write the letter?	A licensed provider: physician, NP, PA, chiropractor, or physical therapist.
How long is it valid?	Commonly about one year; confirm with your plan.
What is the tax benefit?	Paying with pre-tax funds can effectively cut the cost, depending on your tax bracket.

A note on the rules

Every HSA and FSA plan administers these expenses a little differently, and IRS guidance on what counts as a qualified medical expense is detailed. The IRS explains dual-purpose and capital medical expenses in Publication 502. Because eligibility depends on your specific plan, your diagnosis, and current tax rules, confirm the details with your plan administrator and a tax professional before you buy. We are an authorized retailer, not a tax advisor, so treat this page as a starting point rather than a ruling on your situation.

Ready to choose a unit?

Once you understand the letter process, the next step is picking equipment that fits your space and budget. Browse our infrared saunas for sale and cold plunge tubs, both popular choices for home recovery. For the bigger picture on paying with pre-tax dollars, see our overview of using your HSA or FSA for a sauna or cold plunge, estimate your savings with the HSA/FSA savings calculator, and review financing options if you would rather spread the cost. Restore Suite offers free US shipping, real human support, and a best-price guarantee. Questions about which model suits your needs? Our team is glad to help.