If you're enrolled in a Medicare Advantage plan — and roughly 33 million Americans are — there's a good chance that the person reviewing your doctor's request for a hospital stay, a skilled nursing facility transfer, or a specialized procedure isn't a person at all. It's an algorithm. And according to internal documents that have come to light, the AI systems some of the largest Medicare Advantage insurers deployed to handle prior authorization decisions were rushed into service before they were ready, with error rates and oversight gaps that should concern every beneficiary who depends on these plans for their care.
Prior authorization is the process by which your Medicare Advantage plan must approve certain medical services before you receive them. Unlike Original Medicare (Parts A and B), which generally pays for any medically necessary service your doctor orders, Medicare Advantage plans are run by private insurers — companies like UnitedHealthcare, Humana, CVS/Aetna, and Cigna — and they are permitted to require prior authorization as a cost-control tool. That means your cardiologist can't simply schedule your cardiac rehabilitation without first getting a green light from the insurer. Your orthopedic surgeon can't send you to a skilled nursing facility after a hip replacement without the plan's approval. When AI systems are making those approval or denial decisions — and making them badly — the consequences for real patients can be severe.
The core problem revealed in the documents is that these AI pilots were implemented at scale before the systems had been properly validated against real-world patient populations. In plain terms: the algorithms were trained on certain data sets, but when they encountered the full complexity of actual Medicare patients — people with multiple chronic conditions, unusual diagnoses, or care needs that didn't fit neatly into the training data — the systems generated denial recommendations that didn't align with established clinical guidelines. In some cases, the AI flagged requests for denial that a human medical reviewer would have approved without hesitation. The concern isn't just that AI makes mistakes. It's that the mistakes were systematic, they affected vulnerable patients, and the insurers deploying these systems didn't have adequate human oversight in place to catch the errors before they reached beneficiaries.
According to CMS.gov data, Medicare Advantage plans collectively submitted more than 46 million prior authorization requests in 2022 alone, and approximately 2 million of those were initially denied. Of the denials that were appealed, a significant share were ultimately overturned — a pattern that independent analysts and the HHS Office of Inspector General have pointed to as evidence that initial denial rates are too high. When you layer an undertested AI system on top of a prior authorization process that was already generating questionable denials, the risk to beneficiaries compounds. The OIG has previously found that Medicare Advantage organizations sometimes denied requests that met Medicare coverage criteria, meaning beneficiaries were being told no when the answer should have been yes.
For beneficiaries, the practical impact of a wrongful AI-driven denial can be devastating. Consider what happens when a Medicare Advantage plan denies authorization for a post-surgical stay in a skilled nursing facility. The patient — perhaps recovering from a knee replacement at age 74 — is told they must go home, even though their physician believes they need supervised rehabilitation. If that patient or their family doesn't know how to appeal, or doesn't have the energy to fight the denial while recovering from surgery, they may simply comply. They go home before they're ready, they fall, they end up back in the emergency room. The financial and physical costs of that cascade are enormous. And if the original denial was generated by a flawed AI system that never should have flagged the case in the first place, the harm is entirely preventable.
So what can you actually do to protect yourself? The first and most important thing to understand is your appeal rights. Under federal law, Medicare Advantage plans must have a formal appeals process, and for urgent medical situations, you are entitled to a fast-track or expedited appeal decision within 72 hours. For standard (non-urgent) appeals, the plan must respond within 30 days. If the plan upholds its denial, you can escalate to an independent review organization — a third party not affiliated with the insurer — and then further to an administrative law judge if the amount in dispute exceeds $180 (in 2025). These escalation rights exist precisely because Congress recognized that insurers don't always get it right the first time.
When you receive a denial letter, don't just read the first paragraph and give up. The letter is legally required to include the specific clinical criteria the plan used to make its decision. Request those criteria in writing if they aren't included. Then ask your doctor to write a detailed letter of medical necessity that directly addresses each criterion the plan cited. Physicians who are familiar with the appeals process know that vague letters don't win appeals — specific, point-by-point clinical arguments do. If your doctor's office has a patient advocate or a billing specialist who handles prior authorization regularly, loop them in immediately. Many hospitals and large medical practices have dedicated staff for exactly this purpose.
The AI prior authorization problem has attracted serious attention from federal regulators. CMS finalized new rules in 2024 that require Medicare Advantage plans to ensure that prior authorization decisions are made by qualified clinical staff and that AI tools cannot be the sole basis for a denial. Plans are also now required to provide more detailed denial notices and to process prior authorization requests faster than previous standards required. These rules represent meaningful progress, but rules on paper and rules in practice are two different things. Beneficiaries should not assume that because CMS issued new requirements, every insurer is fully compliant. The enforcement landscape is still catching up.
Data Snapshot: According to CMS.gov data from the 2025 Medicare Advantage landscape file, there were 4,971 Medicare Advantage plans available nationwide in 2025, spanning HMO, PPO, PFFS, and SNP plan types. The average Medicare Part B premium in 2025 is $185.00 per month. Among Medicare Advantage plans, CMS star ratings — which measure quality and patient experience on a 1-to-5 scale — show that only about 37% of plans earned 4 stars or higher in the 2025 rating cycle, meaning the majority of plans fall below the threshold CMS considers high-performing. Prior authorization denial rates and appeals outcomes are among the metrics that factor into star ratings, which means plans with aggressive AI-driven denial practices may see their ratings decline over time — giving beneficiaries a market signal to watch.
If you're currently enrolled in a Medicare Advantage plan and you've experienced repeated prior authorization denials, or if you've heard from your doctor that your plan is unusually difficult to work with, the Annual Enrollment Period — which runs from October 15 through December 7 each year — is your primary opportunity to switch plans. During AEP, you can move from one Medicare Advantage plan to another, switch from Medicare Advantage back to Original Medicare, or add or change a Part D drug plan. Changes take effect January 1. There is also an Open Enrollment Period from January 1 through March 31, during which you can make one switch from a Medicare Advantage plan to another Medicare Advantage plan or back to Original Medicare. Use Medicare's Plan Finder tool at Medicare.gov to compare plans by star rating, premium, out-of-pocket maximum, and prior authorization requirements for the specific services you use most.
One underused strategy: before you enroll in any Medicare Advantage plan, call the plan directly and ask how they handle prior authorization for the specific conditions you have. Ask whether they use AI-assisted review tools and what their process is for human clinical review of denials. You won't always get a straight answer, but the quality of the response itself tells you something about how the plan operates. You can also look up a plan's prior authorization requirements in its Evidence of Coverage document, which every plan is required to publish and which is available on the plan's website or through Medicare.gov.
For beneficiaries who are considering leaving Medicare Advantage and returning to Original Medicare, be aware that Medigap (Medicare Supplement) coverage may require medical underwriting if you're outside a guaranteed issue window. In most states, you only have guaranteed issue rights — meaning an insurer cannot deny you or charge you more based on your health — during specific windows, such as the six months after you first enroll in Part B at age 65. However, thirteen states have enacted birthday rules or other protections that give you an annual window to switch Medigap plans without underwriting: California, Idaho, Illinois, Kentucky, Louisiana, Maine, Maryland, Missouri, Nevada, New Jersey, New York, Oklahoma, and Oregon. If you live in one of these states and want to move back to Original Medicare with a Medigap supplement, your birthday window may be your best opportunity to do so without facing coverage denials based on pre-existing conditions.
The broader lesson from the AI prior authorization story is one that Medicare beneficiaries should internalize: your Medicare Advantage plan is a private insurance product, and private insurers have financial incentives to manage costs. That doesn't make them villains, but it does mean you cannot be a passive participant in your own healthcare. Know your plan's prior authorization requirements before you need care. Know your appeal rights before you receive a denial. Keep records of every phone call, every letter, and every interaction with your plan. And if you feel that your plan is consistently standing between you and the care your doctor recommends, you have options — both within the appeals process and at the next enrollment period.