Medicare Advantage Denials and Organization Determinations

In Original Medicare, a claim is usually decided after the care happens: the provider bills, a contractor pays or denies, and the beneficiary learns the outcome from a summary notice. A Medicare Advantage plan works the other way around. The plan itself decides whether an item or service is covered and what it will pay, and it will often decide before the care is furnished, through what the regulations call an organization determination. That single structural difference explains almost everything about how these disputes run — including the fact that an enrollee can force a decision in advance, and that a denial the plan upholds must be handed to an outside reviewer whether or not the enrollee asks.

1.A plan decision is not a claim decision

Both systems produce a yes or a no, but they differ in who decides, when, and what the enrollee can do before the fact.

Original Medicare

A contractor decides the claim, usually after the service. There is generally no way to obtain a binding advance ruling, so a provider who expects a denial gives written notice beforehand instead. The appeal starts with a redetermination by that contractor.

Medicare Advantage

The plan decides, and can be required to decide before care through a pre-service organization determination. Prior authorization is a routine feature. The appeal starts with a reconsideration by the same plan, then moves outside it.

The advance-decision right is the practical advantage of the Part C structure, and it is underused. An enrollee, the enrollee's appointed representative, or the treating physician may ask the plan for a determination before the service happens rather than gambling on the bill. That request is also how the written denial gets created, and no appeal can start without one.

The mirror-image mechanism on the Original Medicare side is the written warning a provider hands over at the desk, described in the entry on advance beneficiary notices. Those notices are not used in Medicare Advantage at all, which regularly confuses patients who have moved between the two.

2.Organization determinations and prior authorization

A plan may require prior authorization for services that Original Medicare would pay without one, and that authority is real but bounded. The plan must decide within timeframes set by regulation, must give written notice of a denial that states the specific reason and the appeal rights, and must apply the same rules to a decision to end care that it applies to a decision to start it.

• The request may come from the enrollee, the enrollee's representative, or the treating physician.
• A pre-service request produces a decision before the service is furnished; a payment request addresses a bill already incurred.
• Expedited handling applies where the standard timeframe could seriously jeopardize life, health, or the ability to regain maximum function.
• A physician's support for expedited handling generally obligates the plan to grant the faster clock.
• An approval, once given, must generally remain valid for the duration of the approved course of treatment.

The standard and expedited windows are fixed by regulation and are short — days for the standard track, hours for the expedited one — but the exact periods are best read from the plan's own notice and from the appeal instructions published on Medicare.gov rather than repeated from memory.

3.The coverage criteria rule

Historically, plans applied proprietary clinical guidelines that were sometimes stricter than Medicare's own rules, which meant care an enrollee would have received in Original Medicare could be refused in a plan. A CMS rule finalized in 2024 tightened that considerably.

Under that rule, a plan must comply with national coverage determinations, applicable local coverage determinations, and general Medicare coverage and benefit conditions when deciding whether an item or service is covered. Internal coverage criteria may be used only where Medicare rules are not fully established, and where they are used the criteria must be based on current evidence in widely used treatment guidelines or clinical literature and must be publicly posted so an enrollee can read them. Denials based on medical necessity must be reviewed by a physician or other appropriate professional with relevant expertise.

As of mid-2026 that framework is the operative rule, and rulemaking in this area has continued year over year — CMS has repeatedly revisited utilization management, prior authorization timelines, and transparency requirements. Read the current position on the CMS site before relying on any summary, including this one.

Caution: The rule constrains the criteria a plan may apply; it does not make every denial improper. A plan may still find that the documented clinical facts do not meet a coverage rule. The useful question on receiving a denial is which criterion was applied and whether it is one the plan was allowed to use.

4.The appeal path

The first step is a reconsideration by the plan itself. That sounds circular, and in one sense it is, but the regulation supplies the fix: if the plan upholds its own denial in whole or in part, it must forward the case to an independent review entity under contract with CMS. The enrollee does not file that step, does not pay for it, and does not need to know it exists for it to happen. Cases move upward automatically.

Above the independent review entity, the path is the same one every other Medicare dispute uses: an administrative law judge, then the Medicare Appeals Council, then federal district court, with amount-in-controversy gates at the judge and court stages. That shared upper structure is set out in the five levels of Medicare review.

An expedited variant runs in parallel for pre-service denials where delay would jeopardize health, compressing the plan's reconsideration into a period measured in hours. A separate fast-track review applies when a plan terminates skilled nursing, home health, or hospice services, handled by a Quality Improvement Organization rather than the plan.

State law occupies a much smaller space here than most people expect. The Medicare statute preempts state standards for Medicare Advantage plans except in defined areas such as licensing and solvency, so the state insurance-code framework that governs commercial coverage — including the bad-faith claims-handling exposure an ordinary insurer faces — generally does not reach a plan's coverage decision. State regulators still license the organization, state balance-billing and consumer-protection statutes still govern what a provider may collect from a patient, and a supplemental or employer-sponsored wraparound policy remains a creature of state insurance law.

5.Questions this raises

The plan approved a course of therapy and then stopped it partway. Is that allowed?

A decision to end care already authorized is itself an organization determination and carries the same notice and appeal rights as an initial refusal. Under the 2024 framework, an approval must generally stay valid for the duration of the approved course of treatment, so a mid-course reversal needs a basis rather than a fresh utilization review. Ask for the written determination and the specific criterion relied on, then appeal.

Can the treating physician get the plan's actual criteria before requesting authorization?

Where a plan applies internal coverage criteria, the 2024 rule requires that they be publicly accessible, so the physician can usually find them on the plan's website and write the request to match. Where Medicare has an established rule instead, the plan is required to apply that rule, and the national or local coverage determination is the document to work from. Either way, quoting the applicable criterion in the request narrows what a denial can rest on.

Does an enrollee have to file the appeal after the plan says no a second time?

No, and this trips people up. If the plan upholds the denial on reconsideration, it must send the case to the independent review entity itself. What the enrollee should do is confirm the file actually went, ask what documentation was transmitted, and supply anything missing. The automatic forwarding covers the filing, not the completeness of the record, and a thin file forwarded promptly is still a thin file.

Is it worth switching back to Original Medicare after a bad denial?

That is an enrollment question rather than an appeal question, and the two run on different calendars. Switching does not resurrect a denied claim, and coverage under a supplemental policy after a switch may depend on state medical-underwriting rules that vary considerably. Enrollment periods and their conditions are published on Medicare.gov, and the Social Security Administration handles the enrollment record itself.

6.Practical sequence

Before the care: ask the plan for a pre-service organization determination in writing rather than letting the provider guess. Have the physician state why the standard timeframe would risk health if speed matters, since that support generally compels the expedited clock.

After a denial: read the notice for the specific criterion relied on, and check whether it is a national or local coverage determination, a general Medicare benefit condition, or an internal plan criterion. If it is internal, look for the public posting and consider whether Medicare rules on the point are in fact established. File the plan reconsideration in writing within the stated window, attach the complete clinical documentation — obtainable under the access right described on the HHS page for individuals — and then confirm the forwarding to independent review rather than waiting to be told. Enrollment and premium questions go to the Social Security Administration, not to the appeal ladder.