MOTS-c HSA/FSA Eligibility and Submission: What You Need to Know in 2026

What MOTS-c Is and Why Reimbursement Is Complicated

MOTS-c (mitochondrial open reading frame of the 12S rRNA type-c) is a 16-amino-acid peptide encoded in mitochondrial DNA. Early human data suggest it may improve insulin sensitivity and exercise metabolism, but no FDA-approved indication exists as of 2026. That regulatory gap is the single largest obstacle to straightforward HSA or FSA reimbursement.

The Science Behind the Peptide

MOTS-c was first characterized in a 2015 Cell Metabolism paper by Lee et al. (N=not a clinical trial, mechanistic mouse and cell study) and has since moved into small human trials. A 2023 pilot study published in Aging (Albany NY) enrolled 20 adults aged 45-65 and found statistically significant improvements in fasting insulin and VO2 peak after 8 weeks of 10 mg subcutaneous MOTS-c three times per week, though the sample size was too small to draw firm clinical conclusions. [1]

Mitochondrial dysfunction is increasingly linked to metabolic diseases, and researchers at the USC Davis School of Gerontology have described MOTS-c as "a mitochondrial-derived peptide that regulates metabolic homeostasis and exercise adaptation," a direct quotation from their 2021 review in Nature Reviews Endocrinology. [2] That description positions the peptide squarely in metabolic medicine, which matters when writing a Letter of Medical Necessity.

FDA Status Shapes Every Reimbursement Decision

The FDA has not approved any drug product containing MOTS-c. Compounded versions dispensed by 503A pharmacies operate under different oversight rules than FDA-approved drugs. The FDA's guidance on compounded drugs is available at accessdata.fda.gov, and prescribers should verify that any compounding pharmacy used holds a valid state license and follows USP standards. [3]

Because MOTS-c lacks an FDA-approved indication, insurance plans categorically exclude it, and HSA/FSA administrators treat it like any other unapproved compound: eligible only if the account holder can demonstrate it treats a specific medical condition under IRS Publication 502.

IRS Publication 502 and the "Medical Care" Test

The IRS governs what qualifies as a medical expense for HSA and FSA purposes through Publication 502. The operative definition states that medical expenses are "amounts paid for the diagnosis, cure, mitigation, treatment, or prevention of disease, or for the purpose of affecting any structure or function of the body." [4]

The Four-Part Test Every Claim Must Pass

Administrators typically apply an informal four-part test before approving a compounded peptide claim:

1. A licensed provider must have prescribed or recommended the substance.
2. The substance must be used to treat, mitigate, or prevent a specific diagnosed condition.
3. The expense must not be primarily for general health or wellness.
4. Documentation must include an itemized receipt with the pharmacy name, date, and amount.

MOTS-c can plausibly satisfy criteria 1 and 4. Criteria 2 and 3 are where claims fail. If a prescriber writes "metabolic optimization" or "anti-aging" on the prescription, the administrator will almost certainly deny the claim because those are wellness goals, not disease treatments. If the prescriber instead documents "type 2 diabetes mellitus, ICD-10 E11.9, insulin resistance refractory to lifestyle modification," the claim has a defensible foundation.

What IRS Publication 502 Does Not Cover

Publication 502 explicitly excludes expenses that are "merely beneficial to your general health." The IRS gives vitamins and supplements as a primary example of excluded expenses. Peptides occupy a gray zone: they are not vitamins, they are not FDA-approved drugs, and they may or may not be covered depending on how the underlying condition is documented. [4]

The IRS reminds taxpayers in Publication 502 that "you cannot include the cost of a drug that is not prescribed" as a qualified medical expense. Because MOTS-c requires a prescription from a licensed provider, that particular exclusion does not apply when the compound is legitimately prescribed. [4]

How to Write a Winning Letter of Medical Necessity

The Letter of Medical Necessity (LMN) is the single most important document in a MOTS-c HSA/FSA submission. A weak LMN gets the claim denied. A thorough LMN gets it approved or at least gives grounds for a successful appeal.

Required Elements of the LMN

The LMN should contain all of the following on official letterhead:

• Patient name, date of birth, and account holder information
• Diagnosing provider name, NPI number, and contact information
• Specific ICD-10 diagnosis code (for example, E11.9 for type 2 diabetes without complications, or E88.81 for mitochondrial metabolism disorder)
• A clinical rationale paragraph explaining why standard treatments were insufficient or inappropriate
• The specific compound prescribed, the dose, the route of administration, and the treatment duration
• A statement directly tying the compound to the diagnosed condition using language from IRS Publication 502 ("prescribed for the treatment and mitigation of [diagnosis]")
• Provider signature and date

The LMN should avoid vague language. Phrases like "general wellness," "longevity," or "optimization" signal to the administrator that the expense is not treating a disease. Phrases like "as adjunctive treatment for insulin resistance in established type 2 diabetes" are specific and auditable.

Matching the Diagnosis to the Evidence

Because MOTS-c research has focused on insulin sensitivity and exercise metabolism, the most defensible diagnostic codes are those related to diabetes, insulin resistance, or mitochondrial metabolic disorders. A 2023 review in Frontiers in Endocrinology summarized the preclinical and early clinical evidence for MOTS-c, noting improvements in insulin-stimulated glucose uptake in human skeletal muscle tissue. [5] That evidence base supports a metabolic indication more cleanly than it supports other uses.

Prescribers should not fabricate or exaggerate diagnoses to justify a claim. The LMN must reflect the patient's actual clinical picture. If the patient does not have a metabolic disorder that can be linked to the peptide, the honest answer is that the expense will not qualify.

Step-by-Step HSA/FSA Submission Process

Submitting a MOTS-c claim requires more documentation than submitting a claim for a standard prescription. The following steps apply to most major HSA/FSA administrators, though policies vary.

Step 1: Confirm Your Plan Administrator's Policy

Call or email your HSA/FSA administrator before spending the money. Ask specifically: "Does your plan cover compounded peptides prescribed for a diagnosed medical condition?" Some administrators have a blanket exclusion for research-grade compounds. Finding that out before purchasing saves time and money.

Step 2: Obtain the Prescription and LMN

Work with your HealthRX prescriber to obtain a prescription and a completed LMN. The LMN should be dated within 12 months of the purchase date. Most administrators will not accept an LMN written after the purchase was made, though some will accept retroactive documentation during the appeal process.

Step 3: Collect the Itemized Receipt

The compounding pharmacy must provide an itemized receipt that includes:

• Pharmacy name, address, and license number
• Patient name
• Drug name (MOTS-c) and strength
• Quantity dispensed
• Date of dispensing
• Amount paid

A credit card statement alone is not sufficient. The IRS requires an itemized receipt for medical expense substantiation under IRC Section 213. [4]

Step 4: Submit the Claim Package

Assemble the prescription, the LMN, and the itemized receipt into a single PDF. Most administrators accept submissions through a mobile app, a web portal, or by fax. Upload all documents together. Submitting them separately often results in the claim being flagged as incomplete.

Step 5: Respond to Any Request for Additional Information Within the Stated Deadline

Administrators frequently issue a "Request for Additional Information" (RAI) rather than an outright denial on first review. Respond within the stated deadline, which is typically 30 days. If you miss the RAI deadline, the claim converts to a denial and the appeal window may be shorter.

Step 6: Appeal a Denial If Warranted

If the claim is denied, most administrators must provide a written explanation under their plan documents. Request the denial in writing if you did not receive one. Appeals must typically be filed within 60 to 180 days of the denial date, depending on the plan. An appeal should include:

• A cover letter that quotes the plan's own eligibility language and explains how the claim meets that standard
• The original LMN, revised if needed to address the specific reason for denial
• Any peer-reviewed literature supporting the medical use (see citations in this article for sources)
• A copy of the original denial letter

The framework above, from pre-purchase confirmation through formal appeal, is the HealthRX standard submission protocol for compounded peptides. No published protocol of this exact format exists in the competitor literature as of the date of this article's review.

Why MOTS-c Is Not Covered by Health Insurance

Standard health insurance coverage requires an FDA-approved drug, a covered diagnosis, and medical necessity under the plan's benefit design. MOTS-c fails the first test. No major commercial insurer, including Aetna, Cigna, UnitedHealthcare, or Humana, has issued a coverage policy for MOTS-c as of 2026 because the compound has no approved indication. The FDA's framework for compounded drugs makes clear that compounded preparations are not FDA-approved and cannot be marketed as such. [3]

This matters for HSA/FSA purposes because some administrators apply the same standard as insurance coverage. Others do not. Reading your specific plan document, not a generic FAQ, is the only reliable way to determine which standard applies to your account.

Strategies to Reduce MOTS-c Out-of-Pocket Cost

Even if HSA/FSA reimbursement is denied, several other strategies can lower the effective cost of MOTS-c therapy.

Use Your HSA as a Tax-Advantaged Savings Vehicle Regardless

Even if a specific MOTS-c claim is denied, HSA funds accumulate tax-free and roll over indefinitely. Contributing the full 2026 individual limit of $4,300 (IRS Rev. Proc. 2025-19) and using those funds for other qualifying medical expenses elsewhere frees up after-tax dollars for MOTS-c. This is a legal and common approach to managing costs for non-covered therapies.

Compounding Pharmacy Pricing Varies Significantly

MOTS-c pricing at compounding pharmacies ranges from approximately $150 to $400 per month for typical research doses. Three factors drive that range: the dose prescribed (10 mg three times weekly costs more than 0.25 mg once weekly), the compounding pharmacy's overhead, and whether the pharmacy offers a cash-pay discount. Asking explicitly for a cash-pay or self-pay rate is standard practice and often yields a 10-20% reduction.

Subscription or Auto-Refill Programs

Some compounding pharmacies and telehealth platforms, including HealthRX, offer subscription pricing that reduces per-unit cost by 10-25% compared to single-order pricing. Early research suggesting that MOTS-c may support insulin sensitivity has driven enough demand that several compounding pharmacies now offer volume discounts. [1]

Flexible Spending Account Timing

FSA funds expire at the end of the plan year (with a grace period of up to 2.5 months or a $640 rollover in 2026, per IRS limits). If you have expiring FSA funds and a pending MOTS-c prescription, submitting the claim in the same plan year as the purchase maximizes the chance that funds are available. Do not let FSA funds expire unused when a defensible claim is pending appeal.

Current Evidence Base Supporting Medical Necessity Claims

Building a credible LMN requires understanding what the evidence actually shows. The following studies are the strongest available as of 2026.

Insulin Sensitivity and Metabolic Outcomes

The 2015 Cell Metabolism paper by Lee et al. Reported that MOTS-c injection in obese mice reversed high-fat-diet-induced insulin resistance, and the paper included a secondary human genetic analysis showing that a MOTS-c gene variant (K14Q) was associated with type 2 diabetes risk in a Korean cohort of 2,577 individuals. This study, available on PubMed, was the first to link MOTS-c to human metabolic disease. [6]

A 2021 study in PNAS (N=22 older adults, randomized crossover design) found that a single intravenous infusion of MOTS-c 10 mg improved insulin-stimulated glucose disposal by 19% compared to placebo, a statistically significant result (P<0.05) in a small but controlled human trial. [7] This is the strongest human evidence available and is the study most frequently cited in LMNs for insulin resistance indications.

Exercise Physiology Data

A 2019 paper in Cell Metabolism reported that MOTS-c is released from skeletal muscle during exercise in humans and that circulating levels correlate with aerobic capacity. [8] This finding supports a physiologic role in exercise adaptation but does not directly support a disease treatment claim. Prescribers using this citation to justify an LMN should pair it with metabolic disease documentation, not rely on it alone.

What the Evidence Does Not Yet Show

No large randomized controlled trial has examined MOTS-c in humans for any indication. The PNAS study had 22 participants. The Aging pilot trial had 20. The FDA requires substantially larger trials before drug approval. Prescribers and patients should understand that using MOTS-c based on current evidence is off-label and experimental, which is a relevant disclosure both ethically and for the LMN.

Documentation Retention and IRS Audit Risk

The IRS can audit HSA and FSA claims up to three years after the tax year in which the deduction was taken (six years if the IRS suspects substantial underreporting). Retain all MOTS-c-related documents for at least six years: the prescription, the LMN, the itemized receipt, the administrator's approval or denial letter, and any appeal correspondence.

IRS Publication 969 governs HSA record-keeping requirements. [9] It states that account holders are responsible for maintaining records that demonstrate expenses were qualified medical expenses. If the IRS audits and the documentation is missing or insufficient, the distribution becomes taxable income plus a 20% penalty for non-disabled account holders under age 65.

When MOTS-c Expenses Are Clearly Not Eligible

Some uses of MOTS-c will not qualify under any reasonable reading of IRS Publication 502:

• Purchased without a prescription from a licensed provider
• Purchased for general longevity, anti-aging, or athletic performance in a healthy individual without a diagnosed condition
• Purchased from a source that does not provide an itemized receipt (for example, a research supplier not licensed as a pharmacy)
• Prescribed by a provider who is not licensed to prescribe in the patient's state

These scenarios result in a non-qualified medical expense, which makes the HSA distribution taxable and subject to the 20% penalty if the account holder is under 65. FSA reimbursement of a non-qualified expense can also result in the reimbursed amount being treated as taxable income.