Key Takeaways
- 01Medicare is two systems for this purpose. Original Medicare requires prior authorization for a narrow, published list. Medicare Advantage requires it as a matter of routine.
- 02In 2026, 55% of eligible Medicare beneficiaries are in Medicare Advantage, and 99% of those enrollees are in plans that require prior authorization for some services. Source: KFF.
- 03Since January 1, 2026, Medicare Advantage plans must decide expedited requests within 72 hours and standard requests within seven calendar days, and must give a specific reason for a denial.
- 04A missed deadline is not an automatic approval. Federal regulation treats it as an adverse determination you can appeal, which is the opposite of what many practices assume.
- 05In 2024, 11.5% of denied Medicare Advantage requests were appealed, and 80.7% of those appeals were partly or fully overturned. Source: KFF.
Two Systems Wearing One Name
Ask whether Medicare requires prior authorization and you will get two correct answers that contradict each other. Both are right. They are describing different programs.
Original Medicare, the traditional fee-for-service program, requires prior authorization for a short and published list of items and services. Medicare Advantage plans are private plans that administer the Medicare benefit, and they set their own authorization requirements on top of it.
That is the whole source of the confusion. A staff member who learned Medicare on the fee-for-service side under-checks, and one who learned it on a Medicare Advantage panel over-checks.
- Prior authorization vs pre-claim review
- They are not the same thing. CMS draws the line by timing. Under prior authorization, the decision comes before the service is rendered. Under pre-claim review, you may render the service first and get the decision before you submit the claim. Both end in an affirmed or non-affirmed decision, but only one of them holds up the care.
What Original Medicare Requires
Less than most practices expect. CMS runs five current initiatives across the whole of fee-for-service Medicare, and everything outside them proceeds without an authorization request.
- Prior authorization for certain hospital outpatient department services.
- Prior authorization for certain durable medical equipment, prosthetics, orthotics and supplies on the Required Prior Authorization List.
- Prior authorization for repetitive scheduled non-emergent ambulance transport.
- The Review Choice Demonstration for Home Health Services.
- The Review Choice Demonstration for Inpatient Rehabilitation Facility Services.
For a therapy or behavioral health practice, that list rarely applies. None of the five covers office-based psychotherapy, psychiatric visits or outpatient therapy clinics; therapy appears only inside home health and inpatient rehabilitation care. The authorizations these practices meet come from Medicare Advantage plans, covered below.
The hospital outpatient list is the one that touches the most physician practices, and it has grown in three steps rather than continuously.
| Required from | Service categories added |
|---|---|
| July 1, 2020 | Blepharoplasty, botulinum toxin injections, panniculectomy, rhinoplasty, vein ablation |
| July 1, 2021 | Implanted spinal neurostimulators, cervical fusion with disc removal |
| July 1, 2023 | Facet joint interventions |
No new service categories have been added since 2023. In its CY 2027 outpatient payment proposed rule (CMS-1850-P), CMS has proposed adding eight more botulinum toxin injection services from July 1, 2027. Recheck the list once the final rule is published, usually in November.
There is also a gold carding scheme running inside Original Medicare that gets very little attention. Under a rule CMS issued in December 2025, DMEPOS suppliers who reach a provisional affirmation rate of 90% or higher can be exempted from prior authorization altogether, and the first exemption cycle began on June 1, 2026.
The WISeR Model, Live in Six States
This is the genuinely new development, and it started this year. The Wasteful and Inappropriate Service Reduction Model runs from January 1, 2026 to December 31, 2031 in New Jersey, Ohio, Oklahoma, Texas, Arizona and Washington.
It applies to a narrow set of Original Medicare items and services, with CMS naming skin substitutes, knee arthroscopy for knee osteoarthritis and electrical nerve stimulation as examples. It covers hospital outpatient departments, ambulatory surgery centers, and office and home settings in those states.
- You choose the mechanism, not whether to be reviewed. Submit a prior authorization request, or submit the claim and have it go to pre-payment medical review instead.
- Determinations usually arrive within three days, and within two days for a confirmed expedited request.
- A recommendation not to affirm must be made by a licensed human clinician. Technology alone cannot produce it.
- Peer-to-peer review is available as part of a resubmission, and resubmissions are unlimited.
- CMS says the model does not change Medicare coverage policy or payment rates.
Medicare Advantage Is Where the Volume Is
If a practice feels buried in Medicare prior authorizations, this is why. The private side of Medicare now covers a majority of beneficiaries and requires authorization at a scale the fee-for-service program does not approach.
The requirement is not spread evenly. On the KFF figures, the shares of Medicare Advantage enrollees in plans requiring authorization run at 97% for acute inpatient stays, 93% for inpatient psychiatric stays, 95% for skilled nursing, 94% for Part B drugs and 90% for home health, but only 6% for preventive services.
That pattern is worth reading as a map. Authorization pressure sits on expensive, extended and post-acute care, which is also where a delay does the most clinical harm.
Three Rules Practices Underuse
These are all settled, published requirements. They are underused because they are not obvious, not because they are contested.
A missed deadline is a denial you can appeal, not an approval
This one is commonly stated backwards. Federal regulation provides that if a Medicare Advantage organization fails to give timely notice of an organization determination, that failure is itself an adverse determination and may be appealed.
The practical difference is large. A practice that believes silence means approval will go ahead and deliver the service. The rule says silence means you have been denied and the clock on your appeal has started.
A patient who switches plans mid-treatment gets 90 days
Coordinated care plans must give a minimum 90-day transition period when an enrollee already undergoing treatment moves to a new Medicare Advantage plan. During that period the new plan may not require prior authorization for the active course of treatment.
The same rule requires that an approval for a course of treatment stays valid for as long as the treatment is medically reasonable and necessary. Both are worth naming directly when a plan asks for a fresh request mid-course.
Your payers now have to publish their own numbers
Under the CMS Interoperability and Prior Authorization Final Rule, impacted payers must publicly report certain prior authorization metrics each year on their own website. The first set was due by March 31, 2026.
This is new leverage. Arguing that a plan is slow used to be a matter of impression, and now it is a matter of a figure the plan published itself.
The Appeal Gap
Two numbers from the same dataset deserve to be read together. In 2024, 11.5% of denied Medicare Advantage prior authorization requests were appealed. Of the appeals that were filed, 80.7% were partly or fully overturned.
Nearly nine in ten denials were accepted without challenge, and the small share that were challenged were usually reversed. Whatever else that says about the denials, it says the appeal is worth filing far more often than it is filed.
A Process That Holds Up
Establish which Medicare you are dealing with
Before anything else, confirm whether the patient is in Original Medicare or a Medicare Advantage plan, and if the latter, which one. The answer changes the requirement, the deadline and the appeal route.
Check the requirement against that specific plan
For Original Medicare, check the published lists, plus the WISeR service list if you practice in one of the six states. For Medicare Advantage, check the plan, because the requirement is set by the plan and not by Medicare.
Submit complete, and route urgent cases to expedited review
An incomplete request restarts the clock rather than pausing it. Where a delay would jeopardize the patient, request expedited review explicitly and attach the documentation that explains the urgency.
Diary the decision deadline
Seven calendar days for a standard Medicare Advantage decision, 72 hours for expedited, and seven calendar days for a standard fee-for-service request under the outpatient and DMEPOS programs. Silence past those dates is something you can act on.
Track expiry and course-of-treatment scope
Record what was approved and for how long, and raise renewals before the last covered visit. Where a course of treatment is involved, hold the plan to the requirement that the approval lasts as long as the treatment remains necessary.
Appeal against the stated reason
Denials must now carry a specific reason. Read it, answer it directly, and treat the appeal as the default rather than the exception, because the published overturn rates do not support treating a denial as final.
Medtransic runs prior authorization for practices as part of the revenue cycle, across Original Medicare, Medicare Advantage and commercial plans. If authorizations are slipping, or denials go unappealed because nobody has the hours, request a free billing review.