Not a traditional prescription — for a water filter you need a Letter of Medical Necessity, which does the same job for equipment that a prescription does for medication. Here is the difference and how to get the right document.
Quick answer
No prescription — you need a Letter of Medical Necessity. For durable equipment like a water filter, the LMN is the correct document and is what FSA/HSA administrators expect.
A prescription is an order for a specific medication or therapy. A Letter of Medical Necessity explains why a product or piece of equipment is needed to treat, mitigate, or prevent a condition. Medicines use prescriptions; durable items like water filters, CPAP supplies, or orthopedic equipment use an LMN. They overlap in spirit — both are a provider documenting medical need — but for a filter, the LMN is the instrument that unlocks reimbursement. See our LMN guide and template.
Because a filter is equipment rather than a dispensed drug, there is nothing for a pharmacy to fill. What your plan needs is documentation that the equipment addresses a health condition — exactly what an LMN provides. With it, the same rules in IRS Publication 502 and IRS Publication 969 that govern other qualified medical expenses apply to your filter.
Two routes, same as any LMN: obtain it through a checkout that issues it after a short survey (fastest, no appointment), or ask your own provider to write one. Either way the letter must be dated on or before purchase. Details are in how to get a Letter of Medical Necessity, and the buying guide shows where it fits in checkout.
Occasionally a provider documents a specific recommendation that reads like a prescription — that is fine, and an LMN can incorporate that detail. The key is not the label on the document but that a licensed provider has connected the filter to a medical need and dated it correctly. Your administrator confirms what format they accept.
SpringWell's TrueMed checkout produces your Letter of Medical Necessity after a short survey — no prescription, no appointment.
Shop eligible systems →Several documents sound interchangeable but are not. A prescription orders a medication. A doctor's note might excuse you from work but rarely satisfies a plan administrator. A Letter of Medical Necessity is the specific document that ties equipment to a condition and is what administrators want for a filter. When in doubt, ask your provider for "a Letter of Medical Necessity for FSA/HSA purposes" by name.
Some plan language uses "prescription" loosely to mean "provider documentation." If your administrator says a prescription is required, ask whether a Letter of Medical Necessity satisfies it — for equipment like a filter, it almost always does. Get their answer in writing if you can, and keep it with your records. See how to get the letter and the documents checklist.
No. You need a Letter of Medical Necessity, which is the correct document for equipment like a filter and is what FSA/HSA administrators expect.
A prescription orders a medication; a Letter of Medical Necessity explains why a product or equipment is medically needed. Filters use an LMN.
Yes. Your provider can issue the LMN, or you can get one through a checkout that issues it after a short health survey. It must be dated on or before purchase.
