Prior Authorization Under Medicare Advantage: What It Is and Why It Matters
If you have ever had a medical procedure delayed, denied, or turned into a months-long battle with an insurance company, you may be familiar with the concept of Prior authorization.
In the world of Medicare Advantage, prior authorization has become one of the most discussed and criticized aspects of the program. If you want the bigger picture first, our overview of why some experts say Medicare Advantage Plans fall short is a good place to start. Understanding how prior authorization works, and what it means for your care, is important whether you are currently on Medicare Advantage or considering your options.
What Is Prior Authorization?
Prior authorization (also called pre-authorization or pre-certification) is a requirement by some health insurance plans that you get approval before receiving certain medical services, procedures, or medications.
The insurance company reviews your doctor’s request and either approves or denies it based on their criteria for Medical necessity.
In theory, prior authorization is designed to prevent unnecessary or inappropriate care. In practice, it has become a major barrier to timely treatment for many patients.
Prior Authorization in Medicare Advantage
Original Medicare (Parts A and B) does not require prior authorization for most medical services. If your doctor determines you need a procedure and it is covered by Medicare, it is generally covered, without needing to ask an insurance company first.
Medicare Advantage plans operate differently. Because Medicare Advantage is administered by private insurance companies, these companies can impose additional requirements, including prior authorization, as long as they cover everything Original Medicare covers.
CMS (the Centers for Medicare & Medicaid Services) allows Medicare Advantage plans to require prior authorization for services, as long as the plan does not use it to deny Medically necessary care.
The result: Medicare Advantage plans can, and do, require prior authorization for a wide range of services, including:
- Inpatient hospital admissions
- Skilled nursing facility stays
- Outpatient surgeries and procedures
- Imaging (MRI, CT scans, PET scans)
- Specialty medications
- Certain specialist visits
- Home health care
- Durable medical equipment
The list of services requiring prior authorization varies by plan and changes annually.
How Common Are Prior Authorization Denials?
Prior authorization denials are a significant problem in Medicare Advantage, according to multiple federal investigations and studies.
A 2022 report by the HHS Office of Inspector General (OIG) found that Medicare Advantage plans denied 13% of prior authorization requests that met Medicare coverage rules, meaning they were appropriate medical care that should have been covered. When plans were audited and these decisions appealed, 75% of denials were reversed.
This means a significant percentage of denied requests were for care that the patient was actually entitled to. The denials were incorrect, but many patients never Appeal. This pattern is part of a broader set of concerns; for more on what to watch for, see our overview of the hidden risks of Medicare Advantage you’re not hearing about.
A separate 2023 KFF (Kaiser Family Foundation) analysis found that millions of prior authorization requests are submitted each year in Medicare Advantage, with varying denial rates across plans.
The practical effect: patients who need care are delayed, discouraged, and sometimes forced to go without treatment, not because their care is inappropriate, but because navigating the prior authorization system is difficult and time-consuming.
How the Prior Authorization Process Works
When your doctor orders a service that requires prior authorization, the general process is:
Your doctor submits a request to your Medicare Advantage plan for authorization, including documentation of medical necessity.
The plan reviews the request. Under CMS rules, plans must generally respond within 72 hours for urgent requests and within a set number of days for standard requests. Check your plan’s Evidence of Coverage for specific timeframes.
The plan approves or denies. If approved, the service can proceed. If denied, your doctor and you are notified of the denial and the reason.
You can appeal. If denied, you have the right to appeal the decision. There are multiple levels of appeal, including an external review by an independent organization.
The problem: even within required timeframes, delays of days or weeks can affect care for serious or urgent conditions. And the appeals process adds additional weeks of waiting.
When Prior Authorization Affects Critical Care
The most serious concern about prior authorization in Medicare Advantage is when delays affect cancer treatment, surgery, post-hospital rehabilitation, or other time-sensitive care.
Cancer treatment: Some Medicare Advantage plans require prior authorization for chemotherapy protocols, targeted therapies, and immunotherapy. A denial or delay while a patient is waiting to start treatment can affect outcomes.
Post-acute care: After a hospitalization, patients often need skilled nursing facility care or home health services. Prior authorization requirements for SNF stays have been cited as a major problem: plans sometimes deny or limit coverage just as patients are ready for discharge, creating dangerous situations.
Specialist access: Some Medicare Advantage plans require referrals and prior authorization for specialist visits. Patients with complex conditions who need multiple specialists may face repeated authorization requirements for ongoing care.
CMS Reforms to Prior Authorization
In response to documented problems, CMS has implemented new rules:
2024 CMS Prior Authorization Rule: Beginning in 2026, Medicare Advantage plans are required to meet new standards for prior authorization decision timeframes and transparency, including public reporting of their prior authorization rates and denial rates.
Gold Carding Exemption: Some payers and state laws allow physicians with strong track records of appropriate authorization requests to be “gold carded,” exempt from routine prior authorization requirements. This is not yet universal in Medicare Advantage.
Continuity of Care: When a patient is mid-treatment and switches Medicare Advantage plans, the new plan generally must continue prior-authorized care for a transition period.
These reforms are progress, but the fundamental structure of prior authorization in Medicare Advantage remains in place.
How Does Medigap Handle Prior Authorization?
Original Medicare plus a Medigap plan does not require prior authorization for covered services.
If your doctor determines you need a procedure and it is covered by Medicare, Medicare pays its share and your Medigap plan pays its share. No one calls a hotline to get approval. No reviewer who has never seen your medical file makes a decision about your care.
This is one of the most significant practical differences between Medicare Advantage and Original Medicare with Medigap, and it is a major reason many retirees consider switching from Medicare Advantage to Medigap.
With a Medigap Plan G, for example:
- Your doctor schedules your MRI → it is covered, no prior auth needed
- Your doctor admits you to the hospital → covered without insurance company approval
- Your doctor refers you to a specialist → you see the specialist, no Referral form required
- You need a 20-day skilled nursing facility stay → covered, no prior auth
The trade-off is that Medigap plans have a monthly Premium. But for many people, particularly those with complex health needs, the elimination of prior authorization requirements is worth the premium cost.
What to Do If Your Medicare Advantage Plan Denies Prior Authorization
If your plan denies a prior authorization request, you have rights.
Ask your doctor to appeal immediately. Your doctor’s office can file an expedited appeal if the denial is for urgent care. The plan must respond within 72 hours for expedited cases.
Request a peer-to-peer review. Your doctor can often request a direct conversation with the plan’s medical reviewer to discuss the clinical rationale for the service.
File a formal appeal. You have the right to appeal denials through Medicare’s formal appeals process.
There are five levels of appeal:
1. Reconsideration (by the plan)
2. Reconsideration by an independent review organization (IRO)
3. Administrative Law Judge hearing
4. Medicare Appeals Council
5. Federal court
Document everything. Keep records of all communications, denial notices, and dates. These records are important for appeals.
Contact your State Health Insurance Assistance Program (SHIP). SHIP counselors provide free help navigating Medicare appeals and denials.
Frequently Asked Questions
Can Medicare Advantage plans deny any service they want using prior authorization?
No. Medicare Advantage plans must cover all services that Original Medicare covers, and they cannot deny claims that meet Medicare’s coverage rules. However, they can impose additional criteria and processes, and some inappropriate denials do occur. The appeals process exists to challenge denials.
How often are prior authorization denials overturned on appeal?
According to the HHS OIG, approximately 75% of appealed Medicare Advantage denials are ultimately overturned, meaning the original denial was wrong. The challenge is that many patients do not appeal.
Does Medigap require prior authorization?
No. Medigap plans do not add prior authorization requirements on top of Original Medicare. If Medicare covers it, Medigap pays its share. No separate approval needed.
My plan denied a skilled nursing facility stay after my hospitalization. Can I appeal?
Yes. SNF denials are a common problem. File an expedited appeal immediately and ask your doctor to provide documentation of medical necessity. You can also request a peer-to-peer review between your doctor and the plan’s medical reviewer.
Bottom Line
Prior authorization is a real and documented problem in Medicare Advantage that delays and sometimes prevents medically necessary care. While CMS continues to push for reforms, the fundamental structure remains in place.
For people who want to avoid prior authorization requirements entirely, Original Medicare plus a Medigap plan provides coverage where your doctor, not an insurance company’s algorithm, makes decisions about your care. If you are still weighing your options, our comparison of Medicare Advantage vs. Medicare Supplement plans can help you decide which path fits your needs.
REMEDIGAP’s licensed advisors can help you compare Medicare Advantage and Medigap options and make the decision that is right for your health and financial situation.
This article is for educational purposes. Medicare Advantage rules, CMS regulations, and prior authorization requirements change frequently. Verify current details at CMS.gov or Medicare.gov, or speak with a licensed Medicare advisor.
💡 Your next step: Thinking about switching from Medicare Advantage? See how Medicare Supplement plans compare to Medicare Advantage — most people are surprised by the difference.
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Written by Michael Quinn
Licensed Broker, REMEDIGAP Founder
Fact Checked by Joann Quinn
Chief Compliance Officer
As a licensed insurance broker, REMEDIGAP upholds the principles of integrity in our editorial standards and ensures transparency in how we receive compensation from our insurance partners.