Does Original Medicare Require Prior Authorization? In Six States, 39 Codes Now Do

ByProf. H

The Briefing: Original Medicare rarely asked permission. In six states, now it does. 39 codes, 6 states, a 46-50 Senate vote.
Background art: Pieter Brueghel the Younger, “The Tax-Collector’s Office” (c. 1615) — public domain, via Wikimedia Commons. Four centuries later the room is a server, but the queue is the same: people waiting on a stranger to read their paperwork.

Mostly no — and then, on January 1, 2026, yes for exactly 39 billing codes in six states. We counted those 39 codes ourselves on September 2, 2026, straight out of Appendix A of the CMS operational guide, and matched them against CMS’s own May 2026 enrollment file: 6,499,285 people are in Original Medicare in Arizona, New Jersey, Ohio, Oklahoma, Texas and Washington, which is 18.9 percent of everyone in Original Medicare nationally.

If you are not in one of those six states, nothing on this page changes your care. If you are, it changes it only if your doctor schedules one of those 39 things. That is a much smaller door than the headlines suggest — and behind it is a payment rule that is genuinely worth understanding, because it decides what your appeal is actually worth.

The short version. The program is called the WISeR Model. It runs January 1, 2026 through December 31, 2031. It applies only to Original Medicare (Part A and Part B) in six states, only to 39 procedure codes, and never to emergency care, inpatient-only services, or anything CMS judged dangerous to delay. It does not apply to Medicare Advantage at all. A private company using AI does the first read; a licensed clinician must sign any denial. This is not medical or financial advice — for your own case call 1-800-MEDICARE (1-800-633-4227, TTY 1-877-486-2048) or your free state counselor.

Does Original Medicare require prior authorization?

For most of its history, barely. That was the quiet selling point of traditional Medicare: you and your doctor decided, and the bill followed. Prior authorization was the thing that happened to other people — people in Medicare Advantage plans, people with commercial insurance, people who had to call a number and wait.

A handful of exceptions always existed, mostly in durable medical equipment, non-emergency ambulance transport, and a few outpatient procedures with a cosmetic twin. But as a general rule, Original Medicare did not ask permission first.

That rule now has a footnote, and the footnote has an address. On July 1, 2025, CMS published a notice in the Federal Register — docket CMS-5056-N — announcing a six-year model that would put prior authorization into fee-for-service Medicare for a narrow set of services, in a narrow set of places, using what the agency calls “enhanced technologies, such as Artificial Intelligence (AI) and Machine Learning (ML), along with human clinical review.”

It started taking requests on January 5, 2026, for services delivered on or after January 15.

A sample Medicare card showing Hospital (Part A) and Medical (Part B) coverage.
The line that decides whether any of this applies to you is printed on the card. Part A and Part B is Original Medicare, and Original Medicare is the only kind the model touches. Image: CMS sample card via medicare.gov — public domain.

What the 39 codes actually are

Here is where the coverage of this program tends to go soft. “Prior authorization is coming to traditional Medicare” is true, and it is also the kind of sentence that lets a reader imagine their next MRI, their cardiologist, their hip replacement. None of those are on the list.

We downloaded the WISeR Provider and Supplier Operational Guide — version 7.0, dated July 24, 2026 — and counted every code in Appendix A on September 2, 2026. There are 13 categories and 39 codes.

Bar chart of the 13 WISeR categories: skin substitutes 8 codes, vertebral augmentation 6, incontinence devices 5, epidural steroid injections 5, impotence treatment 3, hypoglossal nerve stimulation 3, induced lesions of nerve tracts 2, phrenic nerve stimulator 2, and five categories with 1 code each.
Every category on the list, counted from Appendix A of the CMS operational guide on September 2, 2026. Note the shape: the single procedure the press always names — knee arthroscopy — is one code out of 39.

Read that list again and notice what it is. It is wound grafts, spinal cement, nerve stimulators, epidural injections, implanted devices for incontinence and impotence, and one knee operation. These are not the front door of American medicine. They are a specific set of procedures that CMS says have “little to no clinical, evidence-based benefit” for certain patients and a history of billing abuse.

The exclusions matter as much as the inclusions. CMS writes that the model “excludes inpatient-only services, emergency services, and services that would pose a substantial risk to patients if delayed.” Nobody is going to be sitting in an emergency room waiting on an algorithm.

X-ray showing an implanted spinal cord stimulator, with two electrode arrays and a lead visible along the spine.
An implanted spinal cord stimulator, the kind covered by code 63655 in the “electrical nerve stimulators” category. The white rectangles are the electrode contacts. Image: Mconnell, Wikimedia Commons — CC BY 3.0.

Who this can actually reach

To size the group, we pulled CMS’s own Medicare Monthly Enrollment file for May 2026 — the most recent published — from the agency’s public data API on September 2, 2026, and added up the six states.

Funnel chart: 70,465,854 people on Medicare, 34,396,995 in Original Medicare, 6,499,285 in Original Medicare in the six WISeR states, and a fraction of those scheduled for one of the 39 codes.
Each step is a subset of the one above. Enrollment figures are CMS’s May 2026 file, retrieved September 2, 2026.

There is a detail in that data that cuts against the way this story is usually told. Those six states hold 13,432,797 Medicare enrollees in total. Of them, 6,933,512 — 51.6 percent — are in Medicare Advantage. And CMS states it flatly: “WISeR does not apply to people with Medicare Advantage and will have no impact on them.”

So inside the six states chosen for the AI prior authorization pilot, a slight majority of people on Medicare are not in it. They are in the program that has been doing prior authorization at scale for years, by other means.

The sentence that started the fight

Now the part worth your attention. It is not the AI. It is how the reviewing companies get paid.

CMS does not bury this. On its own model page, in plain sight: “Model participants receive a percentage of the expenditures associated with averted wasteful, inappropriate care as a result of their reviews.”

Six companies hold the contracts, one per state: Cohere Health in Texas, Genzeon in New Jersey, Humata Health in Oklahoma, Innovaccer in Ohio, Virtix Health in Washington, and Zyter in Arizona.

In a March 27, 2026 letter to House appropriators, 35 members of Congress described that arrangement in one sentence: WISeR contractors “are compensated via a percentage of the dollar value of the services they deny. This payment mechanism clearly creates a perverse incentive to deny care.”

That is a fair reading of the model page. It is not a complete reading of the payment rule.

What the payment document actually says

The WISeR Payment Methodology is two pages, and it adds a condition that changes the incentive:

“Participants may earn payment for non-affirmation of a prior authorization request for a WISeR item or service, if it does not meet Medicare coverage criteria. The determination must be a unique request and must not have been overturned on resubmission or by appeal.”

And for the other pathway: “CMS will withhold or recoup the WISeR payment for a pre-payment review if the denied claim is successfully appealed.”

Four cards explaining how a WISeR denial gets paid: the request goes in, a licensed clinician must sign the denial, the vendor earns a share of averted spending, but only for a denial that is not overturned on resubmission or appeal.
Read from the CMS WISeR Payment Methodology and operational guide on September 2, 2026. Both are public documents.

So the incentive is not “deny everything.” It is “deny only what will stick.” A denial that gets reversed earns the company nothing, and CMS claws back money already paid. Providers can resubmit an unlimited number of times, can request a peer-to-peer review on each resubmission, and the vendor eats the processing cost each time while collecting, at most, one payment per beneficiary per service.

Which puts an unusual amount of weight on one thing: whether anyone appeals. An appeal you win does not just get your care paid for. It un-pays the reviewer.

Whether that safeguard is strong enough is a real question, and reasonable people are answering it differently. But it is a different question from the one most coverage is asking, and you cannot get to it without reading the second document.

One step deeper: the best number in the case against WISeR is about a program WISeR excludes

The congressional letter makes its argument with a striking statistic: a 2018 HHS Inspector General report found that 75 percent of denied prior authorization requests were overturned on appeal. The letter also cites a KFF estimate that Medicare Advantage insurers made roughly 50 million prior authorization determinations in 2023.

Both figures describe Medicare Advantage. And Medicare Advantage is the one part of the program CMS has explicitly carved out of this model.

That does not make the argument wrong. If anything it is the strongest available evidence for the proposition that prior authorization systems deny things they should not, and it is reasonable to expect a new system to inherit the flaw. But it is borrowed evidence, and it should be labeled as borrowed. We could not verify either figure at the original source today — oig.hhs.gov returned 403 to every automated request we made on September 2, 2026 — so we are citing them as what Congress asserted in a document we did read, not as findings we confirmed ourselves.

The list has been getting shorter, not longer

Here is something we did not expect to find, and have not seen reported anywhere: the operational guide has been revised seven times since October 2025, and the revisions have mostly been subtractions.

Two X-rays side by side showing a vertebral compression fracture before and after balloon kyphoplasty, with injected cement visible in the second image.
Vertebral augmentation — before and after — is the second-largest category on the list, six codes. Image: Rei Momomura, Wikimedia Commons — CC BY 4.0.

Version 3.0 removed CPT 22585 and delayed a planned category (lumbar decompression) entirely. Version 4.0 removed a sleep-apnea diagnosis code and the C5271–C5278 skin substitute codes. Version 6.0 removed a block of wound diagnosis codes and two more skin substitute codes. Version 5.0 added codes for one category. The rest were clarifications.

Three of six substantive revisions narrowed the program. One expanded it. CMS has said it “may add additional services in future years,” so this could reverse. But the first nine months went the other direction, and that is worth knowing if the version of this story you heard was about a program metastasizing.

Congress tried to end it in July, and missed by four votes

After the Government Accountability Office determined the model was subject to the Congressional Review Act, Senate Democrats moved to overturn it. On July 16, 2026, at 1:25 p.m., the Senate took roll call vote 199 on the motion to proceed to S.J.Res. 198.

It failed, 46 to 50, with 4 not voting.

We pulled the roster from senate.gov. The 46 yes votes were 44 Democrats and 2 independents; the 50 no votes were all Republicans. Not one senator crossed.

We then checked the twelve senators who represent the six states where the model actually operates. All twelve voted. Six voted to overturn it — Kelly and Gallego of Arizona, Booker and Kim of New Jersey, Cantwell and Murray of Washington. Six voted to let it stand — Husted and Moreno of Ohio, Lankford and Armstrong of Oklahoma, Cornyn and Cruz of Texas. The split maps exactly onto party, and not at all onto whether a senator’s constituents are in the pilot.

The fight is not over. A House panel has voted to attach language to the FY2027 HHS spending bill barring funds from being used to implement the model. That bill is not law.

What to do with this

1. Check whether you are even in scope. Two conditions, both required: you are in Original Medicare (Part A/Part B, not a Medicare Advantage plan), and you live in Arizona, New Jersey, Ohio, Oklahoma, Texas or Washington. If either is false, stop here.

2. If a procedure is being scheduled, ask one question. “Is this one of the WISeR codes, and are you submitting a prior authorization request or going through pre-payment review?” Your doctor’s office chooses between those two paths. Ask which one they picked.

3. If the answer comes back “non-affirmed,” that is not the end. Providers may resubmit an unlimited number of times and may request a peer-to-peer clinical review with each resubmission. Ask whether they have done either before you accept the outcome.

4. Appeal rights are unchanged. CMS is explicit that beneficiaries keep “all applicable administrative appeal rights under Medicare.” The filing routes are on medicare.gov’s appeals page. Remember what the payment rule says: a successful appeal cancels the reviewer’s payment.

5. Do not pay out of pocket to skip the process. If you are asked to sign something accepting financial responsibility, read what it is before signing, and call for help first.

6. Free human help exists. 1-800-MEDICARE (1-800-633-4227), TTY 1-877-486-2048, 24 hours a day. For one-on-one counseling from someone who is not selling anything, your State Health Insurance Assistance Program at shiphelp.org. Both are free.

If you want to go deeper

Does an AI make the final call? No, according to CMS’s own documents. “All recommendations for non-payment are determined by appropriately licensed clinicians,” and the payment methodology repeats it: “Every non-affirmation must undergo a medical review by an appropriately licensed WISeR clinician or WISeR clinical reviewer.” What the technology does is triage and speed. Whether a clinician reviewing at machine pace is meaningfully reviewing is the argument.

Can this spread to your state? The model is authorized through 2031 in six states, and the Federal Register notice says CMS “may add additional services in future years.” It says nothing about adding states. Any expansion would be new rulemaking, which means a new public document you could read.

Is there a way out for good providers? Yes — a “gold card” exemption. Providers with demonstrated compliance records can be exempted from review entirely, evaluated quarterly.

Where else is AI already touching your money? We have been tracking this: whether AI data centers are raising your electric bill, and how to reach a human when a company puts a bot in front of one.

Frequently asked questions

Does Original Medicare require prior authorization?

Historically, almost never — and still not for the overwhelming majority of care. But since January 1, 2026, 39 billing codes require prior authorization or pre-payment review for people in Original Medicare in six states: Arizona, New Jersey, Ohio, Oklahoma, Texas and Washington. Everything else is unchanged.

Will Original Medicare require prior authorization in 2026?

It already does, for that narrow list. The WISeR Model began January 1, 2026 and is authorized through December 31, 2031. It began accepting requests January 5, 2026, applying to services delivered on or after January 15, 2026.

What is the WISeR model?

WISeR stands for Wasteful and Inappropriate Service Reduction. It is a CMS Innovation Center model that pays private technology companies to review medical necessity for a selected set of services in Original Medicare, using AI and machine learning plus human clinical review. It is the first Innovation Center model in which technology companies are the only participants.

What are the WISeR model states?

Six: Arizona, New Jersey, Ohio, Oklahoma, Texas and Washington. Each is assigned to one company — Zyter in Arizona, Genzeon in New Jersey, Innovaccer in Ohio, Humata Health in Oklahoma, Cohere Health in Texas, and Virtix Health in Washington.

What procedures are on the WISeR 2026 list?

Thirteen categories, 39 codes as of guide version 7.0 dated July 24, 2026: skin substitutes for chronic leg wounds (8 codes), vertebral augmentation (6), incontinence control devices (5), epidural steroid injections (5), treatment of impotence (3), hypoglossal nerve stimulation for sleep apnea (3), induced lesions of nerve tracts (2), phrenic nerve stimulator (2), and one code each for knee arthroscopy, vagus nerve stimulation, electrical nerve stimulators, sacral nerve stimulation and cervical fusion.

Does Medicare use AI to deny claims?

In this model, AI assists the review but does not issue the denial. CMS states that all recommendations for non-payment are determined by appropriately licensed clinicians. The reviewing companies are paid a share of averted spending, but only for determinations that are not overturned on resubmission or appeal — and CMS recoups payment when a denied claim is successfully appealed.

Does this apply to Medicare Advantage?

No. CMS says directly: “WISeR does not apply to people with Medicare Advantage and will have no impact on them.” Medicare Advantage plans run their own separate prior authorization programs, which this model does not govern.

Can I appeal a WISeR denial?

Yes. CMS states that providers, suppliers and beneficiaries “continue to have all applicable administrative appeal rights under Medicare.” Your provider can also resubmit an unlimited number of times and request a peer-to-peer clinical review. Start at medicare.gov’s appeals page, or call 1-800-MEDICARE.

Sources

What we could not confirm. The 75 percent appeal-overturn figure and the 50 million determinations figure appear in the congressional letter linked above; we cite them as that letter’s assertions. Every automated request we made to oig.hhs.gov on September 2, 2026 returned HTTP 403, so we did not verify them at the original reports and have not presented them as our own findings. This article is general information, not medical, legal or financial advice.

Keep reading

Written by Prof. H. Every figure here was read from a federal document or computed from a federal data file on September 2, 2026, and the documents are linked above so you can check the arithmetic. Corrections and questions: the Ask page.

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