Before you switch Medicare plans, check the denial record — not just the premium.

Both tracks: Medicare Advantage and Original Medicare

Medicare’s Annual Enrollment Period (AEP) runs October 15 – December 7. Most plan comparisons stop at premiums, copays, and doctor networks. Those matter.

But almost nobody asks: how often does this insurer say “no” before care happens, and what happens when people appeal?

Medterpret doesn’t tell anyone which plan to pick. Here are the questions to ask and where to look.

1. What “prior authorization” means, and why it matters here

Prior authorization (PA) means the plan must approve a test, procedure, or treatment before you get it. If the plan says no, you can appeal, but the care may wait while you do.

Prior authorization is common in Medicare Advantage. It’s rare in Original Medicare, though that’s changing in a few states (see Section 5).

Here’s the big picture for Medicare Advantage, across all insurers:

Stat card — KFF, calendar year 2024, Medicare Advantage prior-authorization determinations

Medicare Advantage insurers made 52.8 million prior-authorization determinations. 7.7% were denied in full or in part (about 4.1 million). 11.5% of those denials were appealed, and 80.7% of appealed prior-authorization denials were fully or partially overturned.

The same pattern — few appeals, most appeals succeed — held every year from 2019 to 2024.

Here’s the catch. That 80.7% applies only to prior-authorization denials that were appealed. It doesn’t mean any single denial will be overturned. It does mean a denial is often not the last word — and most prior-authorization denials are never appealed.

2. The denial record by insurer

KFF also broke out the 2024 numbers for six large Medicare Advantage parent companies.

Stat card — KFF, CY2024, Medicare Advantage prior-authorization determinations by parent insurer

Insurer level — Medicare does not publish per-plan denial rates.

Parent insurer	Denial rate	Share of denials appealed	Overturned, of those appealed
UnitedHealth	12.6%	12.0%	78.8%
Humana	5.5%	11.6%	64.7%
CVS/Aetna	11.6%	21.4%	92.6%
Elevance/Anthem	4.1%	9.1%	87.9%
Kaiser	10.3%	1.7%	50.2%
Centene/Wellcare	11.9%	7.5%	95.3%

“Overturned” = fully or partially overturned, among prior-authorization denials that were appealed. These per-insurer figures come from KFF’s chart data, which differ slightly from the totals in KFF’s article text (for example, 7.3% vs. 7.7% denied overall).

How to read this: The denial rate is how often the insurer said no up front. The share appealed is how often people pushed back. The overturn rate is how often that first “no” didn’t hold up when someone appealed. A high overturn rate suggests many first denials didn’t stick. KFF notes that Kaiser works differently from the others because it runs its own hospitals and medical groups.

Bottom line: These are company-wide numbers. Your specific plan could be different, and nobody publishes the plan-level figure. Use the table to ask sharper questions, not to pick a plan. More on each insurer: Medicare Advantage denial rates by insurer

3. Plans now post their own numbers — read them carefully

Under a 2024 federal rule (CMS-0057-F, the Interoperability and Prior Authorization Final Rule), Medicare Advantage plans must post on their websites:

• the list of items and services that need prior authorization, and
• their own prior-year prior-authorization numbers: how much was approved, denied, approved after appeal, and how long decisions took.

The first postings, covering 2025, were due by March 31, 2026. Try searching the insurer’s website for “prior authorization metrics.”

Here’s the catch. These postings can’t be compared across insurers, and they shouldn’t be mixed with the KFF table:

• They’re posted by contract, not by company, and they cover 2025, not 2024.
• Formats differ. Some report average days to decide; others report the share decided on time.
• At least one insurer notes that its posted data may differ from what it reports to regulators.

Read each plan’s posting on its own terms.

4. Read your plan’s prior-authorization list

This is the most practical check you can make, and it’s specific to you.

Action step: Get the Evidence of Coverage (EOC) — the plan’s full rulebook — for any plan you’re considering. It’s on the plan’s website. If you’re already in the plan, it had to mail you an Annual Notice of Change (ANOC) by September 30 listing what changes for 2027.

In the EOC, find the medical benefits chart. Services that need approval are usually marked there, often with a phrase like “prior authorization may be required.” Then check the plan’s separate prior-authorization list on its website.

Look for the care you actually use or expect:

• Imaging you get regularly (MRI, CT, PET scans)
• Physical, occupational, or speech therapy
• A planned surgery or procedure
• Home health care, a skilled nursing facility stay, or rehab
• Specialty drugs given in a doctor’s office (Part B drugs), which may also have “step therapy” (you try one drug before another)

Being on the list doesn’t mean you’ll be denied. It means an extra step. Since January 1, 2026, Medicare Advantage plans must decide standard prior-authorization requests within 7 calendar days (72 hours when waiting could seriously harm your health), and must give a specific reason if they deny.

5. Original Medicare has some prior authorization now, too

Original Medicare track

Leaving Medicare Advantage to avoid prior authorization? Original Medicare now has some, too.

A Medicare pilot called WISeR (the Wasteful and Inappropriate Service Reduction Model) runs from January 1, 2026 through December 31, 2031, in six states: New Jersey, Ohio, Oklahoma, Texas, Arizona, and Washington. It adds prior authorization or pre-payment review for roughly 15 to 17 select outpatient services, such as epidural steroid injections, knee arthroscopy for osteoarthritis, and skin and tissue substitutes. Private vendors use AI-assisted tools, but a licensed clinician must make any final denial. Emergency services and inpatient-only services are excluded.

News reports say the launch has been rocky. STAT News reported on September 15, 2026, that records obtained by the Electronic Frontier Foundation (EFF) show a rushed, error-prone launch. The Medicare Rights Center reported on September 24, 2026, that the records show inappropriate delays and denials.

Most Original Medicare services still need no advance approval. If you live in one of these six states, ask your doctor’s office whether WISeR affects your care.

6. The Medigap warning before you leave Original Medicare

Both tracks

If you have Original Medicare with a Medigap (Medicare Supplement) policy and you’re thinking of switching to Medicare Advantage, slow down.

Here’s the catch. You can’t use a Medigap policy with a Medicare Advantage plan. If you drop Medigap to join a Medicare Advantage plan and later want to come back, in most states Medigap insurers can ask health questions (called medical underwriting). They can charge more or say no.

The exception: If you drop Medigap to join a Medicare Advantage plan for the first time, you have a “trial right.” If you switch back to Original Medicare within the first 12 months, you can get Medigap again without health questions — usually your old policy, if the company still sells it. After that, the door may close.

Action step: Before you drop a Medigap policy, ask a State Health Insurance Assistance Program (SHIP) counselor how the rules work in your state. SHIP help is free.

7. Questions to ask before you switch

Ask your SHIP counselor or the plan’s member services, and use Medicare’s Plan Finder to compare:

1. Which of my services, drugs, and planned procedures need prior authorization in this plan?
2. How does this plan decide prior-authorization requests, and how fast?
3. What does this plan’s own posted prior-authorization data show for its contract?
4. If I’m in the middle of treatment, how will a new plan handle it?
5. Do my doctors, hospital, and therapists take this plan — and have they had trouble getting approvals from it?
6. If I’m leaving Original Medicare, can I get back into Medigap later in my state?

What to do this week

• [ ] Write down the services, drugs, and procedures you use or expect next year.
• [ ] Get the Evidence of Coverage for your current plan and any plan you’re considering.
• [ ] Check each plan’s prior-authorization list against your list.
• [ ] Look up the insurer in the KFF table above — as one input, not the answer.
• [ ] If you have Medigap, don’t drop it until you’ve talked with SHIP.
• [ ] Book a free SHIP appointment before December 7, and compare plans in Medicare Plan Finder.

Got a denial or a confusing notice? Upload it to Medterpret and see what it says, what it means, and what to do next — in plain English. Medterpret drafts; you decide what to send. Appeal a denial →

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Medterpret is independent and not affiliated with or endorsed by Medicare, CMS, HHS, or any government agency. Educational information, not legal or medical advice.

Sources

1. “Medicare Advantage Insurers Made Nearly 53 Million Prior Authorization Determinations in 2024” (article and chart data), KFF, January 28, 2026. kff.org
2. “CMS Interoperability and Prior Authorization Final Rule (CMS-0057-F),” fact sheet, Centers for Medicare & Medicaid Services (CMS), January 17, 2024. cms.gov
3. “WISeR (Wasteful and Inappropriate Service Reduction) Model,” CMS Innovation Center, accessed September 29, 2026. cms.gov
4. “Medicare’s AI prior authorization pilot was rushed and full of problems, new documents reveal,” STAT News (Brittany Trang), September 15, 2026. statnews.com
5. “New Records Reveal Problems with Medicare’s AI Prior Authorization Experiment,” Electronic Frontier Foundation, September 8, 2026. eff.org
6. “New Records Show Medicare WISeR AI Prior Authorization Model Causing Inappropriate Denials of Care,” Medicare Rights Center, September 24, 2026. medicarerights.org
7. “Get ready to buy” (Medigap trial rights and health questions), Medicare.gov, accessed September 29, 2026. medicare.gov
8. Medicare Plan Finder, Medicare.gov. medicare.gov
9. “Get Medicare Help from Your Local SHIP Program,” SHIP Technical Assistance Center, accessed September 29, 2026. shiphelp.org