Free Tool

HSA Eligibility Checker

Instantly check if an expense is HSA eligible. Search for any medical expense to see if you can pay with your HSA tax-free.

Eligible

Prescriptions, doctor visits

Maybe

Requires documentation

Not Eligible

Gym, vitamins (usually)

What is a Letter of Medical Necessity (LMN)?

A Letter of Medical Necessity is a document from your doctor that explains why a specific expense is medically necessary for your condition. It's required for some HSA expenses that might otherwise be considered personal.

When you need an LMN:

  • Therapeutic massages for a diagnosed condition
  • Supplements prescribed for a deficiency
  • Exercise equipment for rehabilitation
  • Air purifiers for respiratory conditions
  • Special mattresses or chairs for medical conditions

Ask your doctor to write an LMN that includes your diagnosis, why the expense is necessary, and how long you'll need it.

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Last updated: May 2026