A Letter of Medical Necessity (LMN) is a document provided by a licensed healthcare provider that explains a patient’s medical condition, the recommended treatment, and why the treatment is medically necessary. An LMN may be required to support the use of certain expenses under tax-advantaged accounts such as HSAs, FSAs, or HRAs.
To be acceptable, an LMN should include the patient’s name and date of birth, the condition being treated, the doctor-recommended treatment, and a clear explanation of why it is medically necessary. The letter should also be signed by the treating physician or licensed provider.
An LMN cannot make an otherwise ineligible expense eligible. It only confirms that a treatment is medically necessary where IRS rules already permit. For example, tooth bonding to restore medical function may be eligible with an LMN, while cosmetic bonding would not. Always review IRS guidance and your plan details to determine what qualifies.
If you need an LMN, ask your treating provider. Lively also provides a downloadable LMN form, which can be accessed from your account dashboard or in the "Attachments" below.
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