KFF analyzed the transparency data insurers file with the federal government and found that Marketplace plans denied 19% of in-network claims in 2024. Out of roughly 85 million denied in-network claims, consumers appealed at least 262,982.
That is an appeal rate under 1%. Of the ones that were appealed, insurers upheld 66%, which means about a third were overturned.
Read those two numbers together and the picture is uncomfortable. The appeal process works often enough to be worth using, and almost nobody uses it. A prior authorization denial is not a verdict. It is the first round of a process with federal deadlines, a free right to the plan’s own clinical criteria, and an independent reviewer at the end who does not work for your insurer.
The step most prior authorization denial guides leave out
Search for help with a prior authorization denial and you will find solid advice about getting the denial reason in writing, gathering records and filing an internal appeal. What the top results underplay is that the internal appeal is not the end of the line.
Under 45 CFR 147.136, non-grandfathered health plans must provide both an internal appeal and, after that, an external review by an independent review organization that has no relationship to your plan. The external reviewer’s decision binds the insurer. In states whose external review process meets federal minimum standards, the state runs it. Where a state does not have a qualifying process, there is an HHS-administered federal external review process instead.
That second stage is the one people never reach, because they read the internal denial as final. It is also where a genuinely wrong clinical determination is most likely to be reversed, because the person reading it is not the company that wrote the denial.
The calendar, which is the part that actually kills appeals
Deadlines do more damage here than arguments do. The federal framework gives you:
At least 180 days from the denial notice to file an internal appeal. That is generous, and it is the deadline people still miss.
For an urgent claim, a decision as soon as possible and no later than 72 hours. This is the expedited track, and you have to ask for it by name and have your doctor state that delay would jeopardize your health.
For a pre-service denial, which is what a prior authorization refusal is, a decision within 30 days. For a post-service claim, 60 days.
Then four months from the final internal denial to request external review, with a standard decision inside 45 days and an expedited one inside 72 hours.
One right worth invoking in writing at the start: the plan must give you, free of charge, access to and copies of all documents relevant to your claim, including the specific clinical rationale for the denial. Ask for the criteria by name. If a plan denied an MRI as not medically necessary, you want the exact clinical policy it applied, because appeals are won by showing your documentation satisfies the plan’s own written standard rather than by arguing the standard is unfair.
What is at stake in dollars
The reason the calendar matters is that the alternative to appealing is paying. A denied imaging study commonly runs in the low thousands, and a denied biologic infusion can run several thousand a month. Those are market ranges rather than published figures, so treat them as orders of magnitude, but the shape is right: a prior authorization denial on a drug converts a copay into a full retail price, every month, until somebody reverses it.
Which is why an appeal rate under 1% is so striking. The expected value of a few hours of paperwork against a third chance of reversing a four-figure monthly cost is not a close call.
Two shortcuts the formal process hides
Before you write anything, have your prescribing doctor request a peer-to-peer review. This is a direct conversation between your physician and the plan’s medical director, and it frequently resolves denials in days rather than weeks because it skips the documentation round entirely. It is not a right under the regulations, it is an administrative practice, and you generally have to ask for it.
Second, find out which set of rules you are actually under, because it changes who you escalate to. If you have a fully insured plan bought through an employer or the Marketplace, your state insurance department is in the loop and the state external review process is available. If your employer self-funds its plan, which is how most large employers operate, you are under the ERISA claims procedure at 29 CFR 2560.503-1 instead, and your state insurance department has no authority over it. Same illness, same denial, different escalation path. Ask your HR or benefits contact whether the plan is self-funded before you waste a week complaining to the wrong regulator.
The denial rates are not random
If you want evidence that initial denials run high rather than accurate, the HHS Office of Inspector General published two reports in June 2026 examining the 19 largest Medicare Advantage organizations using June 2024 data covering 29.3 million enrollees.
Those plans overturned 95% of appealed prior authorization denials for skilled nursing facility admissions. Ninety-five percent. OIG framed that finding exactly as you would expect: when nearly every appealed denial gets reversed, the problem is the initial denials.
The same reports found denial rates of 65% for long-term acute care hospitals and 54% for inpatient rehabilitation facilities, with only 36% to 43% overturned on appeal in those categories.
Physicians report the downstream effect. The American Medical Association’s 2025 prior authorization survey, released in 2026, found 95% of physicians say prior authorization delays access to necessary care and 79% say patients abandon treatment because of it. Abandonment is the outcome insurers are effectively underwriting when they deny at volume, and it is why the process depends on you not appealing.
What is changing
The Interoperability and Prior Authorization rule, CMS-0057-F, was finalized in January 2024 and published in the Federal Register, and its compliance dates have started landing. As of January 1, 2026, affected payers must give a specific reason for a prior authorization denial, and they had to begin publicly reporting prior authorization metrics by March 31, 2026. The application programming interface requirements, including a dedicated prior authorization API, take effect January 1, 2027. The rule covers Medicare Advantage organizations, state Medicaid and CHIP programs, Medicaid and CHIP managed care plans, and qualified health plan issuers on the federally facilitated exchanges.
The practical upshot for you is the denial-reason requirement. A denial that says only “not medically necessary” is less defensible than it was two years ago.
What to do this week
If you are holding a denial right now, do four things in this order. Call and ask whether your plan is self-funded. Ask your doctor’s office to request a peer-to-peer review today. Send a written request for the complete claim file and the specific clinical criteria used, citing your right to them free of charge. Then calendar two dates: your 180-day internal appeal deadline and, once that comes back, the four-month external review window.
And if the denial concerns something time-sensitive, say the words expedited appeal and get your physician to document that a delay would jeopardize your health. That moves the decision clock from 30 days to 72 hours. A prior authorization denial is designed to be absorbed rather than contested, and the statistics show it usually is. While you are dealing with the plan, how to read an EOB and fight a balance bill covers the billing side of the same fight.
