Medical necessity is a concept used by insurance providers, including Medicare, to determine whether they’ll cover certain types of medical care. Generally, medically necessary services are those that are needed to diagnose or treat an illness, injury, condition or disease and align with accepted standards of treatment.
For example, if you have a bacterial infection, you need to take antibiotics. If health care providers need to determine whether you have a broken bone, you’ll need to have an X-ray.
Some procedures, medications and services may be more ambiguous, as medical conditions are often complex and have multiple possible treatment plans. In those cases, you’ll want to talk with your provider about getting prior authorization from your insurance company so that you can be sure your medical treatment is covered.
[READ: How and Why to File a Medicare Appeal]
What Counts as “Medically Necessary” Under Medicare?
You may hear insurance companies use the term “medical necessity” when talking about services covered by your plan.
“(Medical necessity) refers to care that is reasonable, appropriate and essential for your health,” says Dr. Saamer Siddiqi, a Chicago-based board-certified internal medicine hospitalist and founder and CEO of LIVEMED, a company that supports rural and community hospitals. “It’s the kind of treatment a doctor determines is needed to diagnose, treat or prevent a serious condition, rather than something done for convenience, preference or cosmetic reasons.”
For the most part, clinics, hospitals and physician groups follow treatment protocols that are in line with broadly accepted standards of medical care. “For example, prescribing statins for someone with high cholesterol will generally meet the standard of medical necessity, so will X-rays to determine if a bone is broken or surgery for repair of a hernia,” says Whitney Stidom, vice president of consumer enablement at eHealth, an online health insurance marketplace..
Yet whether a procedure is medically necessary also may depend on the standard of practice for health care practices in your area, as well as any state laws governing medical necessity.
[READ: Does Medicare Require Prior Authorization?]
The High Cost of a Medical Necessity Claim Denial
If you have Medicare or private health insurance, it’s important to understand the idea of medical necessity, as it can determine what your health care plan will cover or not cover. Each health insurance policy will define medical necessity and their standards and procedures within the policy. How they define medical necessity will impact which procedures they cover.
When you’re part of a health plan like Medicare, medical necessity matters because claims submitted for services that do not meet the criteria of medical necessity are typically denied, meaning the full cost is passed on to the patient.
“No one wants a surprise medical bill, and it can be especially frustrating to seek medical care at a doctor’s recommendation only for the claim to be denied by your insurer,” Stidom says.
[READ: Medicare Mistakes to Avoid.]
Do You Need a Certificate of Medical Necessity?
Previously, Medicare required a Certificate of Medical Necessity for coverage of certain services or medical equipment and supplies.
“While the form is no longer needed, providers still need to produce orders and provide documentation that the patient meets Medicare’s coverage criteria for the equipment or service,” says Christen Bergeron, founder of the Bedford, New Hampshire-based Navigating Senior Living, which helps families understand care options.
The definition of medical necessity will depend on national coverage decisions regarding Medicare as well as your state laws. Nationally, the Centers for Medicare and Medicaid Services (CMS) uses data and research to make national coverage determinations (NCDs), which determine whether or not a procedure is covered by original Medicare. When a procedure does not fall under a NCD, it’s up to the Medicare contractors to make a local coverage determination (LCD).
Does medical necessity apply to Medicare Advantage plans?
Medicare Advantage plans can set their own standards for what is medically necessary, but they must cover, at a minimum, the same health services that original Medicare covers. They may also set their own requirements for prior authorization, which may mean that the plan has to approve your services before you receive them.
What about medical necessity for Medicaid?
Since states are responsible for administering Medicaid, each state has a definition of “medical necessity” outlined for their Medicaid programs. You can find your state’s definition of what is “medically necessary” within the state Medicaid policy if you’re eligible for Medicaid.
[READ: Medicare vs. Medicaid: Navigating Dual Eligibility in 2026]
Which Procedures and Medications Are Medically Necessary?
The best way to find out if medical treatments that you need are considered medically necessary is by reading the policy documents, says Barbara Hopkins, a licensed insurance agent and Medicare consultant based in South Portland, Maine. Although they may be hard to follow, they’re an important part of understanding your coverage.
Some examples of care that are typically considered medically necessary include:
— Anesthesia for many types of surgery
— Antibiotics for an infection
— Cardiac rehabilitation
— Mammogram screening to detect breast cancer
— Oxygen when you can’t breathe
— X-rays to determine if you have a broken bone
Procedures and Medications Often Deemed “Not Medically Necessary”
Health services that may not meet the definition of medical necessity and therefore may not be covered by Medicare include:
| Category | Example |
| Durable medical equipment that Medicare considers only for “convenience” | Grab bars and shower chairs |
| Cosmetic procedures | Botox for non-medical reasons |
| Experimental surgeries | Non-FDA-approved robotic or advanced stem cell surgeries |
| Off-label medications | Metformin for weight loss, since it’s only approved for Type 2 diabetes |
| Tests unrelated to your health problems | Full-body MRIs |
Keep in mind that there are other types of health needs that Medicare Parts A and B do not cover. They may be medically important, but they are covered within different types of Medicare coverage, like Medicare Advantage (also called Part C) plans, Hopkins says. These include:
— Eye exams for prescription glasses
— Hearing aids and the exams to fit them
How to Get Pre-Approved Before Your Procedure
If you’re unsure if a medication, test or treatment is necessary for your health problem, just ask your provider, “Is this really necessary for me, or is it extra?” or “Should we ask for pre-approval?” Simply asking the question can help you assess if something is valuable for your time and may help you avoid an unexpected bill.
It also can be useful to work with your health provider’s office to determine if prior authorization (pre-approval) is needed for a test, treatment or service. This involves getting prior approval for a medication or treatment to ensure that it will be covered by your plan.
“If there’s any doubt, filing a prior authorization request with the insurer can save them a lot of worry and hassle, and potentially a lot of money, too,” Stidom says.
Each insurance plan, be it for Medicare or non-Medicare plans, will have a prior authorization process. Often, a provider will write a letter to explain a person’s condition and why the specific treatment should be approved. The provider also may send lab results or medical records to further support the care they are recommending.
It may take up to a few weeks to hear if a prior authorization request is approved. Final decisions are made by considering the information in the prior authorization request, the stipulated benefits and coverage of the health insurance plan, and broadly accepted standards of medical practice.
What to Do If Your Medicare Claim Is Denied
If your Medicare claim or prior authorization for a specific medication, service or treatment is denied, take a deep breath.
“It’s not a horrible, scary thing if you’re denied,” Hopkins says.
A 2025 Health Affairs study found that 17% of claims through Medicare Advantage were denied, but 57% of those were ultimately overturned.
“Most people stop too early, but a lot of denials get overturned once the details are laid out,” Siddiqi says. “An appeal gives you a chance to add missing records, provider letters or other evidence that shows why the care is necessary.”
“A strong, well-written letter can open the door where a simple claim might have been turned away,” Siddiqi adds.
Work with your health provider to file an appeal if a claim is denied. Your provider’s office can give more details in writing about why you need a certain type of treatment and share more background about your medical situation. You can also work with your State Health Insurance Assistance Program (SHIP), which has counselors who will answer questions for free regarding Medicare or Medicare Advantage, Bergeron says.
If you or someone you care for is in need of durable medical equipment, it also can be helpful to work with health providers to find alternatives if a certain item isn’t covered. For instance, Medicare may not cover the cost of a raised toilet seat, but it will cover a bedside commode chair. Plus, if you have Medicare Advantage, it may cover some items that original Medicare won’t pay for.
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Will Medicare Cover Your Next Treatment? How Medical Necessity Is Decided originally appeared on usnews.com
Update 07/24/26: This story was published at an earlier date and has been updated with new information.
