Home > Resources > Letters of medical necessity: The ultimate guide
Published July 8, 2022
When you look at a list of eligible expenses for your HSA, you will frequently come across the term "letter of medical necessity." For most items, it's usually clear if they're covered by insurance or your HSA or not. However, some items fall into a gray area that require a letter of medical necessity. In this article we'll go into detail about what a letter of medical actually is and some frequently asked questions about them.
Put simply, a letter of medical necessity, or LMN, is a letter written by your doctor or medical provider that states a treatment, drug, or product is medically necessary and therefore should be covered to some extent by insurance.
You might need a letter of medical necessity if your doctor suggests a treatment that falls outside what's typically covered by insurance or your HSA.
An example might be if you suffer from tennis elbow and your doctor suggests physical therapy. The physical therapist may then suggest a treatment program that includes dumbbell exercises. Because dumbbells aren't typically covered by insurance or an HSA, most people would just pay for the dumbbells out of pocket. However, some clever folks might try to get insurance to cover them, but you would likely need to get a letter of medical necessity first.
Your doctor would write a letter of medical necessity for you, which he or she would then submit to your insurance on your behalf. You could also submit the letter to your insurance yourself.
Insurance companies determine medical necessity essentially by asking if the treatment, service, or item requested is essential to improve or maintain good health. For the tennis elbow example above, an insurance company may make the judgment that dumbbells are required to treat tennis elbow. However, they could also deny the claim even though your physical therapist prescribed exercises that require them. It's really a gray area that all depends on the policies of the insurance company or even just the judgment of person or people reviewing the letter.
While a nurse, physician's assistant, physical therapist, or other medical professional can write a letter of medical necessity, insurance companies typically require the letter to be signed by your primary care physician. If you have questions about the requirements your insurance company has, it's always best to call and ask so you don't waste your time.
A letter of medical necessity is typically valid for one year from the date on the letter, but again, you should confirm this with your insurance company because their requirements may be different.
While thinking about asking your insurance provider to cover an expense that typically isn't covered may seem daunting at first, it's a lot easier when you understand the process and the role a letter of medical necessity plays. If you have any questions about your plan's specific coverage or how they handle letters of medical necessity, we recommend talking to your insurance company or benefits administrator directly about the best way to proceed in asking them to cover an expense.