Medicare prior authorization in 2026: what it is, when it applies, and your appeal rights

Recent updates

• June 2025 — Major Medicare Advantage carriers voluntarily committed to streamline prior authorization starting 2026–2027 (see What’s changing in 2026).
• January 2026 — CMS launched the WISeR pilot for Original Medicare prior authorization in six states.
• January 2026 — Medicare Advantage plans must now decide standard prior authorization requests within 7 calendar days (down from 14) and expedited requests within 72 hours, under CMS-0057-F.
• January 2026 — Medicare Advantage plans must include a specific reason for every denial. Vague “not medically necessary” letters are no longer allowed.

Short answer

Prior authorization is when your Medicare plan requires approval before you receive a service or fill a prescription. Original Medicare requires it for only a short list of items and services. Medicare Advantage plans require it for many more — inpatient stays, skilled nursing, specialist referrals, imaging, and higher-cost drugs. If a request is denied, you can appeal. Most appeals that are filed succeed.

What prior authorization is (and what it isn’t)

Prior authorization is a coverage-approval process. Your doctor sends your Medicare plan the clinical justification for a service, drug, or piece of equipment. The plan reviews the request against its coverage rules and either approves or denies it. The service itself is not blocked — you can still receive it — but if the plan denies the request, it will not pay.

In practice, providers usually wait for approval before scheduling non-emergency services that require prior authorization. That is because if the service goes ahead and the plan later refuses to pay, you may be left with the full bill. Emergency care is treated differently — plans cannot require prior authorization for emergency services.

It is worth being precise about what prior authorization is not:

• It is not a referral. A referral is a primary care doctor sending you to a specialist. Whether an HMO plan requires a referral, prior authorization, or both — and for which services — varies by plan. Check your plan’s specific rules.
• It is not a pre-claim review. Pre-claim review happens after the service is delivered but before the claim is paid. Original Medicare uses this for a small list of items and services in certain states.
• It is not a medical necessity denial at claim time. That is a separate coverage decision made after the service. Prior authorization tries to answer the same question upfront.

Knowing which of these is happening to you matters, because the timelines and appeal paths are different for each.

Original Medicare and prior authorization

Original Medicare — Parts A and B, sometimes called Traditional Medicare or fee-for-service — has historically used prior authorization for only a narrow list of items and services. In 2023, Original Medicare processed about 400,000 prior authorization reviews, compared to nearly 50 million in Medicare Advantage that same year. That is roughly one review per 100 beneficiaries.

The current Original Medicare prior authorization list, as of July 2026:

• Durable medical equipment, prosthetics, and orthotics (DMEPOS): power mobility devices, lower-limb prosthetics, certain off-the-shelf back and knee braces, and pressure-reducing support surfaces.
• Hospital outpatient department services: blepharoplasty, botulinum toxin injections, panniculectomy, rhinoplasty, vein ablation, implanted spinal neurostimulators, cervical fusion with disc removal, and certain facet joint interventions.
• Ambulatory Surgical Center demonstration: launched December 2025 in 10 states (California, Florida, Texas, Arizona, Ohio, Tennessee, Pennsylvania, Maryland, Georgia, New York), covering blepharoplasty, botulinum toxin, panniculectomy, rhinoplasty, and vein ablation.
• Home Health Review Choice Demonstration: Illinois, Ohio, Texas, North Carolina, Florida.
• Inpatient Rehabilitation Facility Review Choice Demonstration: Alabama, Pennsylvania, and Texas (from March 2, 2026); California added May 1, 2026.
• Repetitive Scheduled Non-Emergent Ambulance Transports (RSNAT): nationwide.
• WISeR pilot: 6 states as of January 2026 (see below).

CMS updates this list periodically — items are added, removed, or paused as demonstrations conclude and new pilots launch. If in doubt, ask your provider to check the current list for the specific service code before you schedule.

Everything else in Original Medicare — office visits, imaging like MRI or CT, most surgery, most physical therapy, most lab work — does not require prior authorization. Your provider bills Medicare after the service, and Medicare pays based on medical necessity.

If your Original Medicare provider is denied at claim time for something that was not subject to prior authorization, that is a coverage decision, not a prior authorization denial. The appeals process is different — see the appeals section below.

Medicare Advantage and prior authorization

Medicare Advantage — Part C — is different. Virtually all Medicare Advantage enrollees, 99% as of 2024, are in plans that require prior authorization for at least some services. In 2024, Medicare Advantage insurers made about 53 million prior authorization determinations (KFF, 2024 data), up from 50 million in 2023 and 42 million in 2022. That works out to nearly two determinations per enrollee.

Services most commonly requiring prior authorization in Medicare Advantage:

• Inpatient hospital admissions and observation stays
• Skilled nursing facility stays and inpatient rehabilitation
• Home health services
• Advanced imaging: MRI, CT, PET scans
• Specialist visits, especially for HMO plans
• Physical, occupational, and speech therapy beyond initial visits
• Durable medical equipment
• Higher-cost prescription drugs, including many Part B injectables like chemotherapy

Denial rates vary by service and by plan. Across all Medicare Advantage in 2024, plans fully or partially denied 7.7% of requests — up slightly from 6.4% in 2023. That means about 4.1 million requests were denied in 2024 alone. Denial rates for post-acute care (skilled nursing, inpatient rehab, home health) run considerably higher — an inpatient rehab survey covering July–August 2024 found initial denial rates above 57%.

The important pattern is what happens next. Only 11.5% of denied requests were appealed in 2024. But of those that were appealed, more than 80% were fully or partially overturned (KFF, 2024 data). Since 2019 — every year, without exception — over 8 in 10 appealed denials have been reversed on appeal. That is the strongest single argument in this guide: if you receive a denial, appeal it.

The plans know this. Some of the largest Medicare Advantage carriers have committed to reduce the number of services requiring prior authorization and to expand “gold card” programs that exempt high-performing providers from prior authorization altogether. Whether these voluntary changes reach you depends on your plan and your doctor.

Part D and prescription drug prior authorization

Prior authorization for prescription drugs works differently from medical services. Under Medicare Part D — and the drug benefit built into most Medicare Advantage plans — the pharmacy is often where the process starts: when you try to fill the prescription, the pharmacy system flags that the drug requires prior authorization and notifies both you and the prescriber. Your prescriber’s office then submits a coverage determination request to the plan.

Part D also uses two related tools that often get confused with prior authorization:

• Step therapy: the plan requires you to try a lower-cost drug first before covering the one your doctor prescribed.
• Quantity limits: the plan caps the number of pills or doses per month.

Common 2026 examples of drugs that frequently trigger prior authorization under Medicare include GLP-1 medications (such as Ozempic, Mounjaro, and Wegovy) when prescribed for Medicare-covered indications like type 2 diabetes or cardiovascular disease risk reduction. Medicare does not cover GLP-1s prescribed for weight loss alone, so those requests fall outside the Medicare prior authorization path entirely. Other frequent triggers include high-cost specialty biologics, some anticoagulants, and select oncology drugs.

If your drug requires prior authorization, or is subject to step therapy, or exceeds a quantity limit, your prescriber can file for one of three formal exceptions:

1. Formulary exception — the drug isn’t on the plan’s approved list, and your prescriber attests it is medically necessary.
2. Tiering exception — the drug is on the formulary but at a higher cost tier than a comparable alternative.
3. Coverage determination for prior authorization — the drug is on the formulary but requires review.

Timelines are tighter than for medical services. Standard coverage determinations must be decided within 72 hours. Expedited requests, for cases where waiting would seriously jeopardize your health, must be decided within 24 hours.

If the plan denies your coverage determination, you have the right to appeal — and the same pattern holds: most drug appeals that get filed are overturned.

What services require prior authorization in 2026

There is no single national list because each Medicare Advantage plan and each Part D formulary sets its own rules. That said, the services most likely to require prior authorization in 2026, across most Medicare Advantage plans:

• Non-emergency inpatient hospital admissions
• Skilled nursing facility admissions and continued stays beyond an initial window
• Inpatient rehabilitation
• Home health services
• Advanced imaging (MRI, CT, PET, nuclear cardiology)
• Genetic testing and specialized lab panels
• Physical, occupational, and speech therapy beyond the plan’s covered baseline
• Sleep studies and CPAP equipment
• Durable medical equipment above set price thresholds
• Part B injectable drugs, especially chemotherapy and biologics
• Certain specialty and high-cost Part D drugs, including many GLP-1s when prescribed for Medicare-covered indications

If you have Original Medicare, the list is much shorter — see the Original Medicare section above.

How to know for sure: your Medicare Advantage plan’s Evidence of Coverage, the plan’s prior authorization list on its website, and your Part D formulary all tell you exactly what needs approval. If you cannot find it, call the number on the back of your plan card and ask.

What’s changing in 2026: WISeR, CMS-0057-F, and voluntary industry commitments {#whats-changing}

Three separate 2026 changes are worth understanding together, because they affect different parts of Medicare in different ways.

The WISeR pilot program

WISeR — the Wasteful and Inappropriate Service Reduction Model — is the CMS Innovation Center’s Medicare prior authorization pilot program. It launched January 1, 2026 and runs for six years, through December 31, 2031. The pilot operates in six states: Arizona, New Jersey, Ohio, Oklahoma, Texas, and Washington.

Under the WISeR pilot program, Original Medicare providers in those six states must either request prior authorization or accept a pre-payment medical review for a defined list of outpatient services. The list includes skin substitutes for wound care, electrical nerve stimulator implants, epidural steroid injections for pain, bone cement injections for spinal compression fractures, cervical fusion, and arthroscopic knee surgery for osteoarthritis, among others. Deep brain stimulation and percutaneous image-guided lumbar decompression were initially proposed but delayed by CMS; the agency updates the list over time.

What is genuinely new about WISeR:

• Contractors use artificial intelligence and machine learning to help review requests. Final denial decisions must be made by a licensed clinician with relevant subject-matter expertise.
• Standard turnaround is 72 hours; expedited requests are decided within 48 hours.
• Denied providers can resubmit an unlimited number of times and can request a peer-to-peer clinical review.
• CMS pays the contractors a percentage of the savings from denied requests — a design that critics have flagged as a possible incentive to deny more than necessary. CMS says the contractors are also measured on accuracy and provider experience.

If you have Original Medicare and live in one of the six pilot states, you may notice that certain outpatient procedures now go through an approval step that they did not before. Medicare Advantage patients are not subject to WISeR — their plans already handle prior authorization directly. Emergency and inpatient services are excluded from WISeR entirely.

CMS-0057-F — the interoperability and prior authorization rule

Separate from WISeR, the CMS Interoperability and Prior Authorization Final Rule (CMS-0057-F) sets new operational standards for Medicare Advantage plans, state Medicaid programs, CHIP, and Qualified Health Plans on the federal insurance exchanges. Two operational changes took effect January 1, 2026:

• Standard prior authorization decisions: 7 calendar days, down from 14.
• Expedited (urgent) decisions: 72 hours.
• Specific denial reason: every denial must state the specific clinical or coverage reason, not a vague catch-all.

Additional API and data-sharing requirements take effect January 1, 2027. The rule does not cover Part D prescription drug prior authorization — those timelines are set separately (72 hours standard, 24 hours expedited).

Voluntary industry commitments

In June 2025, most large Medicare Advantage carriers publicly committed to reduce the number of services subject to prior authorization, streamline electronic submission, and expand gold-card exemption programs for providers with strong approval records. Some of this is beginning to reach patients through 2026 and 2027. Whether your plan has actually reduced its list depends on the plan — the commitments were voluntary, and independent surveys of practicing physicians have found early results have been uneven.

What this means for you

If you have Medicare Advantage anywhere in the country, decisions on your prior authorization requests should now come faster and with clearer explanations. If you have Original Medicare in one of the six WISeR states, some outpatient procedures now go through an approval step. And if you have Part D, the changes to Medicare Advantage medical prior authorization do not change your drug approval process.

How to check whether a service needs prior authorization

Before you schedule a service or fill a prescription, check whether prior authorization is required. Four reliable ways:

1. Ask your doctor’s office. Most practices have staff who handle prior authorization every day and know which of the plan’s rules apply.
2. Read your Evidence of Coverage. Medicare Advantage and Part D plans publish this document annually. It lists everything requiring prior authorization, step therapy, or quantity limits.
3. Log in to your plan’s member portal. Most plans have a searchable prior authorization list and a formulary search tool.
4. Call member services. The number is on the back of your plan card. Ask specifically about the service code — the CPT or HCPCS code your doctor plans to bill.

If you have Original Medicare, most services do not require prior authorization at all. The exceptions are listed above in the Original Medicare section. When in doubt, ask your provider to check.

If your prior authorization is denied: your appeal rights

You have the right to appeal every prior authorization denial. The path depends on which part of Medicare you have.

Medicare Advantage uses a five-level appeal process:

1. Reconsideration by the plan itself. You have 60 days from the denial notice to request it. Standard decisions come back in 30 days; expedited in 72 hours.
2. Independent Review Entity — an external contractor CMS uses to review plan denials.
3. Administrative Law Judge hearing.
4. Medicare Appeals Council review.
5. Federal district court.

Most appeals that succeed do so at levels 1 or 2.

Part D has its own coverage determination and appeal path — a coverage determination first, then a redetermination, then an Independent Review Entity review. Standard redeterminations must be decided within 7 days; expedited within 72 hours.

Original Medicare prior authorization denials are handled by resubmission and, if necessary, the standard Medicare appeals process for post-service coverage denials. WISeR denials specifically allow unlimited resubmission and peer-to-peer clinical review before any formal appeal.

Appeals go better when your treating provider stays engaged. The clinical justification, medical records, and any peer-reviewed literature that support the request typically come from your provider’s office — not from you. Ask your doctor whether they can submit a letter of medical necessity and, for Medicare Advantage, whether they can request a peer-to-peer clinical review with the plan’s medical director.

Keep a communication log. From the moment a prior authorization or denial enters the picture, keep dated records of every phone call, letter, portal message, and voicemail — including the name of the representative you spoke to, the reference or case number, and what was said or promised. Save copies of everything you submit and every response you receive. If a case moves to appeal, that log is often the difference between a decision that hinges on your word and one that hinges on documented facts.

For a step-by-step guide with a sample appeal letter and expedited appeal walkthrough, see Baba’s Medicare denial appeal guide and the companion prior authorization denial guide.

When prior authorization is NOT your barrier

Not every denied claim is a prior authorization problem. Before you file a prior authorization appeal, check whether the real issue is one of these:

• Medical necessity denial without a prior authorization requirement. The service went through, but the plan is now refusing to pay because it does not consider the service medically necessary. This is a claim denial, not a prior authorization denial. The appeal path is similar but the paperwork is different.
• Formulary exclusion. The drug is not on the plan’s list at all — no prior authorization step, just not covered. The path is a formulary exception, not a prior authorization appeal.
• Coordination of benefits errors. If you have Medicare plus other coverage (retiree health, Veterans Affairs benefits, employer coverage), a claim may be denied because the plans are unclear on who pays first. Fixing the coordination fixes the claim without any prior authorization step.
• Coding errors. The provider billed the wrong code, and the plan denied it as non-covered. The provider corrects and rebills.
• Advance Beneficiary Notice. If your Original Medicare provider had you sign an Advance Beneficiary Notice before the service, they warned you Medicare might not pay. You have limited appeal rights there.

Sorting out which of these is happening usually takes a phone call to the plan, a phone call to the provider’s billing office, or both. A patient advocate can do this for you.

How Baba helps

Baba advocates handle prior authorization work every day. Medicare may cover qualifying patient advocacy or care navigation services — talk to Baba to find out if you qualify. What that looks like in practice:

• Plan document review. Your advocate reads your Evidence of Coverage, plan card, and any recent denial or coverage letters, so you know what your plan actually requires.
• Coverage lookup. Before a service is scheduled, your advocate confirms whether prior authorization is needed, checks the plan’s list, and identifies the correct service codes.
• Cross-party communication. Prior authorization stalls often come from the doctor’s office, the plan, and the pharmacy each waiting on one of the others. Your advocate acts as the connective tissue — following up with each party, chasing missing clinical documentation, and making sure nobody drops the file.
• Appeal preparation. If a request is denied, your advocate helps assemble the medical justification, drafts the appeal letter, and tracks deadlines. Where appropriate, your advocate also helps your doctor’s office prepare a peer-to-peer clinical review.
• Escalation. If the plan misses a deadline or applies the wrong standard, your advocate knows the next step — expedited appeal, Independent Review Entity, or a call to your state insurance department.

Most Baba clients pay nothing out of pocket for these services when Medicare covers the work.