An HSA or FSA administrator needs a Letter of Medical Necessity before it will reimburse celiac-related expenses like the gluten free food premium, prescribed supplements, or nutrition counseling.
This template gives your physician the exact diagnosis codes, medical-necessity language, and eligible-expense list the administrator is looking for, grounded in Internal Revenue Code Section 213(d) and the framework in IRS Publication 502.
A one-page physician letter addressed to your HSA or FSA plan administrator. It is distinct from the doctor's letter for your tax records; the LMN is what your benefits administrator files, names the specific eligible expense categories, and is typically valid for the maximum duration the plan allows.
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Every version is an editable starting draft, never a locked template. Edit it to fit your situation before you send it.
Bracketed fields are for you or your doctor to fill in. Everything else is the language that makes the letter work.
Provider letterhead
[Provider name or practice letterhead]
[Provider street address]
[City, State, ZIP]
[Phone, fax, secure email]
Date: [MM / DD / YYYY]
To: HSA or FSA Plan Administrator (or whom it may concern)
Re: Letter of Medical Necessity for [Patient name]
Patient name: [Patient full legal name]
Date of birth: [MM / DD / YYYY]
Patient address: [Street, City, State, ZIP]
Insurance ID or member ID, if applicable: [Member ID]
Diagnosis
I am the treating physician for the above named patient. The patient has been diagnosed with celiac disease.
- Primary ICD-10 diagnosis code: K90.0 (Celiac disease)
- Date of diagnosis: [MM / DD / YYYY]
- Method of diagnosis: [for example, positive serology, including tTG-IgA, EMA, or DGP, with confirmatory small bowel biopsy showing villous atrophy consistent with Marsh classification]
- Additional related ICD-10 codes, if applicable: [for example, L13.0 dermatitis herpetiformis; D50.9 iron deficiency anemia; M85.80 osteopenia; K90.4 malabsorption due to intolerance]
Medical necessity of a strict gluten free diet
A strict, lifelong gluten free diet is the only medically accepted treatment for celiac disease. It is medically necessary for this patient to:
- Prevent ongoing autoimmune damage to the small intestine.
- Avoid serious complications, including malabsorption, anemia, osteoporosis, infertility, neurological symptoms, refractory celiac disease, and an elevated risk of small bowel lymphoma.
- Maintain remission and resolution of symptoms.
Specific expenses that are medically necessary
The following expenses are medically necessary for the treatment of this patient's celiac disease and should be considered eligible medical expenses under Internal Revenue Code Section 213(d) and the framework set out in IRS Revenue Ruling 55-261 and IRS Publication 502:
- The incremental cost of certified gluten free food above the cost of conventional, gluten containing equivalents.
- The full cost of specialty gluten free items that have no conventional counterpart, including but not limited to xanthan gum, guar gum, sorghum flour, certified gluten free oats, dedicated gluten free flour blends, and certified gluten free baking mixes.
- Mileage and travel costs related to obtaining gluten free food, attending celiac related medical appointments, and accessing celiac safe dining or specialty stores when local options are unavailable.
- Nutrition counseling and follow up appointments related to celiac disease management.
- Medically prescribed supplements related to celiac associated deficiencies, including but not limited to iron, vitamin B12, vitamin D, calcium, and folate.
- Diagnostic and follow up testing, including endoscopy, biopsy, antibody panels, and bone density scans where clinically indicated.
Duration of treatment
This patient requires a strict gluten free diet for life. Celiac disease is a chronic, lifelong autoimmune condition with no cure other than complete and ongoing avoidance of gluten. This Letter of Medical Necessity should therefore be considered ongoing.
For administrative purposes, please consider this letter valid for the maximum duration permitted by the plan. I am happy to provide an updated letter on request.
Provider certification
I certify that the above information is true and accurate to the best of my knowledge, and that the medical necessity described is based on my direct examination, diagnosis, and ongoing treatment of this patient.
Provider name (printed): [Dr. Full Name]
Credentials: [MD or DO or NP or PA, plus board certification]
NPI number: [10 digit NPI]
State license number: [License number, State]
Provider signature: ______________________________
Date signed: [MM / DD / YYYY]
The eligible-expense framework comes from primary IRS guidance.
- Internal Revenue Code Section 213(d) (Cornell LII) law.cornell.edu/uscode/text/26/213
- IRS Publication 502, Medical and Dental Expenses irs.gov/pub/irs-pdf/p502.pdf
- IRS Private Letter Ruling 202311001 irs.gov/pub/irs-wd/202311001.pdf
Friendly reminder. This template is general educational information, not tax, legal, or medical advice. Plan rules vary; confirm your administrator's documentation requirements, and have your CPA or tax professional review anything you also track on Schedule A.