Does Medicare Require Prior Authorization? (2026 Rules)

Whether Medicare requires prior authorization depends on which Medicare you have: Original Medicare rarely does, while Medicare Advantage plans may require it before covering certain services. That's how Medicare's own booklet on Medicare Advantage puts it: in most cases Original Medicare doesn't need approval, while a Medicare Advantage plan may need to approve certain services or items first.1 So does Medicare require prior authorization for your parent's next scan, scooter or surgery? Start by finding out which kind of Medicare they have, because the two sides play by different rules.

In This Guide

• Original Medicare vs. Medicare Advantage at a Glance
• When Does Original Medicare Require Prior Authorization?
• The WISeR Model: Prior Authorization Tests in Six States
• How Prior Authorization Works in Medicare Advantage
• Medicare Advantage Prior Authorization Deadlines in 2026
• What Happens If a Request Is Denied
• Should Prior Authorization Change Which Medicare You Pick?
• Frequently Asked Questions
• Learn More

Original Medicare vs. Medicare Advantage at a Glance

Prior authorization just means someone has to sign off before the care is paid for. Here's how the two sides of Medicare handle it.

In Original Medicare, the decision times in this table belong to CMS's equipment and hospital outpatient prior authorization programs, and the after-approval caveat to the equipment program.1 In Medicare Advantage, the 72-hour and 7-day deadlines come from a 2024 CMS rule known as CMS-0057-F,4 and the rule that a plan can't take back an approval comes from 42 CFR 422.138.3

When Does Original Medicare Require Prior Authorization?

So does Original Medicare require prior authorization? Usually not, and that's the honest headline. But "usually" is doing some work there. CMS runs several fee-for-service prior authorization programs for Original Medicare. Two of CMS's Original Medicare programs make prior authorization mandatory: certain medical equipment and certain hospital outpatient procedures. A third CMS program, for repetitive, scheduled non-emergency ambulance transport, makes prior authorization in Original Medicare voluntary.1

Certain medical equipment (DMEPOS)

For some durable medical equipment, prosthetics, orthotics and supplies, Original Medicare makes prior authorization a condition of payment. The items are the ones CMS places on its Required Prior Authorization List, and power mobility devices and pressure-reducing support surfaces are on it. An Original Medicare claim for an item on the Required Prior Authorization List has to be tied to an approved prior authorization to be paid. CMS says the process helps "ensure that Medicare patients are not held responsible for the cost of items that are not eligible for Medicare."1

The Required Prior Authorization List grows. CMS's July 2026 update adds eight more equipment codes to the Required Prior Authorization List, including certain orthoses, a pressure-reducing support surface and a manual wheelchair base, with prior authorization required nationwide starting October 28, 2026 for most of them.1 If your dad is getting a power chair, our guide to Medicare wheelchair and scooter coverage covers the rest of that process.

When the need is urgent, the treating practitioner can ask Medicare for an expedited review of the equipment request, or use the ST modifier that flags an acute need.1

Certain hospital outpatient procedures

CMS also requires prior authorization in Original Medicare for a set of procedures done in hospital outpatient departments. The CMS hospital outpatient list has three dated groups: blepharoplasty, botulinum toxin injections, panniculectomy, rhinoplasty and vein ablation since July 1, 2020; implanted spinal neurostimulators and cervical fusion with disc removal since July 1, 2021; and facet joint interventions since July 1, 2023.1

CMS states that the hospital outpatient program keeps "the medical necessity documentation requirements unchanged for providers." In plain terms, the doctor sends Medicare the same records it would want anyway, just before the procedure instead of after.1

Repeat non-emergency ambulance rides

For repetitive, scheduled non-emergency ambulance transport (RSNAT), prior authorization in Original Medicare is voluntary. CMS's own words: "Prior authorization for RSNAT is voluntary." An ambulance supplier that skips RSNAT prior authorization has those claims reviewed before payment instead.1 Our guide to non-emergency ambulance rides to dialysis has the details.

How fast Original Medicare decides

For prior authorization requests submitted on or after January 1, 2025, Original Medicare's standard review in the equipment and hospital outpatient programs takes no more than 7 calendar days, and an expedited review is decided in 2 business days. Medicare's RSNAT ambulance program moved to the same 7-calendar-day standard on January 9, 2025, but it no longer offers expedited review, because those rides are scheduled in advance.1

CMS lists other Original Medicare review programs on the same pages, including a prior authorization demonstration for certain ambulatory surgical center services and review choice demonstrations for home health and inpatient rehabilitation services.1 If your provider mentions one of those, ask which program applies and what they need from you.

The WISeR Model: Prior Authorization Tests in Six States

This one is new, and it's the part of the answer most likely to surprise people. The WISeR (Wasteful and Inappropriate Service Reduction) Model tests prior authorization in Original Medicare for a select set of items and services in six states: New Jersey, Ohio, Oklahoma, Texas, Arizona and Washington. The WISeR Model runs six performance years, from January 1, 2026 to December 31, 2031.2

The services CMS names as WISeR examples are skin and tissue substitutes, electrical nerve stimulator implants, and knee arthroscopy for knee osteoarthritis. CMS has delayed WISeR review for two services on its original list, deep brain stimulation for essential tremor and Parkinson's disease and percutaneous image-guided lumbar decompression for spinal stenosis, until a future date it will announce in the Federal Register.2

Here's how it plays out if you live in one of those six states. For a service selected for the WISeR Model, your provider chooses: submit a prior authorization request, or skip it and have the claim go through pre-payment medical review instead.2 Either way, that choice belongs to the provider or supplier, not to you.

Three protections come with it:

• If a WISeR Model review recommends that Medicare not pay for your service, that recommendation has to come from appropriately licensed clinicians.2
• CMS states that "WISeR does not change Medicare coverage or payment policy" and that "WISeR does not apply to people with Medicare Advantage and will have no impact on them."2
• If Medicare denies your claim under the WISeR Model, you can appeal, and you keep your full administrative appeal rights under the existing Original Medicare claim appeal process.2

How Prior Authorization Works in Medicare Advantage

A Medicare Advantage plan has to cover all medically necessary Part A and Part B services that Original Medicare covers, except hospice, which Original Medicare keeps covering. But the plan manages how you get that care, and prior authorization is one of its tools: Medicare Advantage plans may require plan approval before covering certain services or items, which Original Medicare generally does not.5 Our guide to how Medicare Advantage works covers networks and costs.

Here's what surprises most families: a Medicare Advantage plan can't use prior authorization however it likes. Three federal limits do the heavy lifting.

• It needs a medical reason. Under 42 CFR 422.138(b), a Medicare Advantage plan of the kind the regulation calls a coordinated care plan may use prior authorization only to confirm the diagnosis or other medical criteria a coverage decision rests on, to make sure a basic benefit is medically necessary, or to make sure an extra, supplemental benefit is clinically appropriate. Medicare Advantage private fee-for-service plans can't use prior authorization at all.3
• It plays by Medicare's rulebook. Medicare Advantage plans must use Original Medicare's coverage criteria, including national and local coverage determinations, when deciding whether a basic benefit is medically necessary. A Medicare Advantage plan may use its own internal criteria only in three narrow cases where Medicare's criteria aren't fully established, and when it does, it must make those criteria publicly accessible along with the evidence behind them. So if your mom's plan cites its own policy, you can ask to see it.3
• A yes stays a yes. Once a Medicare Advantage plan approves a service through prior authorization, it may not later deny coverage for lack of medical necessity, and it may not reopen that decision except for good cause or reliable evidence of fraud or similar fault.3

If you're in the middle of treatment

Say your dad is partway through a course of treatment. The continuity-of-care rule at 42 CFR 422.112 applies to what the regulation calls Medicare Advantage coordinated care plans, and only to their basic benefits. Under 42 CFR 422.112, a Medicare Advantage coordinated care plan's approved prior authorization for a course of treatment "must be valid for as long as medically necessary to avoid disruptions in care." Under 42 CFR 422.112, a Medicare Advantage coordinated care plan must also give a new enrollee who is mid-treatment, whether new to the plan or new to Medicare, at least a 90-day transition period, even with an out-of-network provider, during which the plan "must not disrupt or require reauthorization for an active course of treatment."3

Medicare Advantage Prior Authorization Deadlines in 2026

This is where 2026 changed things for Medicare Advantage members. Under the CMS Interoperability and Prior Authorization Final Rule (CMS-0057-F), starting January 1, 2026, Medicare Advantage plans must send prior authorization decisions within 72 hours for expedited, urgent requests and within 7 calendar days for standard requests.4

CMS-0057-F gives you two more things:

• A real reason. Beginning in 2026, a Medicare Advantage plan must give a specific reason when it denies a prior authorization request, whether the decision goes out by portal, fax, email, mail or phone.4
• Public numbers. Medicare Advantage plans must post certain prior authorization metrics on their websites every year, with the first set due by March 31, 2026. If you're comparing plans, that posted data is worth a look.4

One big exception: none of CMS-0057-F's provisions apply to prior authorization decisions for drugs. A drug denial still runs on the notice and appeal rules that already govern that plan, which CMS-0057-F left unchanged.4 For a denied prescription, our guide to asking your drug plan to cover a denied drug walks through the steps.

What Happens If a Request Is Denied

A denial isn't the end of the road on either side of Medicare. What comes next depends on which Medicare you have.

In Original Medicare's equipment program, a denied prior authorization request (CMS calls it a non-affirmation) can be resubmitted. The regulation says the requester "may resubmit a prior authorization request before the item is furnished to the beneficiary and before the claim is submitted for processing." A resubmitted equipment request is the chance to send documentation showing that Medicare's coverage, coding and payment rules are met, since those are the rules a non-affirmation says weren't met.1 If you end up appealing a claim, our guide to the Medicare appeals process covers each level.

In Medicare Advantage, you start by asking the plan to reconsider, and you have 65 days from the date on the Medicare Advantage plan's denial notice to file. If the plan says no again, the Medicare Advantage plan must automatically send your case to an Independent Review Entity. If waiting could seriously jeopardize your life, health or ability to regain maximum function, ask for a fast appeal, which a Medicare Advantage plan generally decides within 72 hours.6 Our guide to what to do when your Medicare Advantage plan denies care walks through that fight step by step.

Should Prior Authorization Change Which Medicare You Pick?

It's a fair thing to weigh. If avoiding prior authorization matters a lot to you, Original Medicare's short lists are a real point in its favor. Medicare Advantage brings other trade-offs: networks, extra benefits, and a yearly in-network out-of-pocket cap that federal rules limit to $9,250 for Part A and Part B services in 2026, something Original Medicare doesn't have.5

Watch the Medigap piece. You can't use a Medigap policy to pay Medicare Advantage costs. If you join a Medicare Advantage plan for the first time and aren't happy, you have a trial right under federal law to buy a Medigap policy if you return to Original Medicare within 12 months of joining.5 Our side-by-side guide to Original Medicare vs. Medicare Advantage covers the full decision.

Not sure which plan your parent is in, or how their plan handles prior authorization? A State Health Insurance Assistance Program (SHIP) counselor can go over it with you. Here's what SHIP counseling is and how it works.

Learn More

Find personalized help sorting out Medicare prior authorization rules at brevy.com.

The information on Brevy.com is for educational purposes only and is not a substitute for professional legal, financial, or medical advice. Rules vary by state and program and change frequently. Always verify with the relevant agency or a qualified professional. Brevy is not a law firm, financial advisor, or healthcare provider.