Your doctor orders a scan, a surgery, or a drug. Then nothing happens, because the plan has to approve it first. That gap between the order and the care is prior authorization, and it is the single most common complaint insured Americans have about their coverage. In a KFF Health Tracking Poll published February 2, 2026, 69% of insured adults called prior authorizations burdensome and 34% picked them as the single biggest burden in getting health care, ahead of every other option offered.
This page covers what prior authorization is, who submits what to whom, which plans are bound by which rules as of September 2026, and your options when the answer is no or never comes. If your only question is how many days it should take, that has its own page: how long does prior authorization take.
What Is Prior Authorization
HealthCare.gov defines preauthorization as “a decision by your health insurer or plan that a health care service, treatment plan, prescription drug or durable medical equipment is medically necessary.” The same term goes by prior authorization, prior approval, precertification, and preapproval depending on who is writing the letter. They all mean the same thing.
Two features of that definition do most of the damage in practice. First, it happens before you get the care, not after. Emergencies are the exception, and plans may not require preauthorization for emergency services. Everything else can be gated.
Second, and this is the part people miss, HealthCare.gov states plainly that “preauthorization isn’t a promise your health insurance or plan will cover the cost.” An approval clears the medical-necessity hurdle. It does not zero out your deductible, copay, or coinsurance, and it does not make an out-of-network provider in-network. Those are separate questions, covered in in-network vs out-of-network and copay vs coinsurance.
Medicare Advantage is the one place where an approval is close to binding. Under 42 CFR 422.138, once a Medicare Advantage plan has approved an item or service through prior authorization, it may not later deny coverage on the basis of lack of medical necessity, and may not reopen the decision except for good cause or reliable evidence of fraud.
How Prior Authorization Works
The process has four moving parts, and you are not the one operating any of them.
Who submits it. Your provider does, not you. For a procedure or imaging study, the ordering physician’s office sends clinical documentation to the plan or to the utilization-management vendor the plan hired. For a drug, you usually find out at the pharmacy counter: the claim rejects with a prior authorization code and your prescriber has to submit separately. Nobody automatically tells the prescriber that the claim rejected, which is why prescriptions sit in limbo for days. Call the prescriber yourself the same day.
What the plan does with it. A reviewer, often a nurse first, compares the request against the plan’s written clinical criteria. Approvals at this stage are frequently automated. Denials are supposed to be different: many states require that only a licensed clinician can deny for medical necessity, and CMS-0057-F requires impacted payers to state a specific reason for a denial as of 2026.
Peer-to-peer review. If the request is heading for denial or has already been denied, your physician can usually request a peer-to-peer, a scheduled phone call with the plan’s medical director to argue the case directly. It is fast, it is free to you, and it resolves a meaningful share of borderline cases before a formal appeal is ever filed. You cannot request it yourself, but you can ask your doctor’s office whether they have.
Step therapy and fail-first. Step therapy requires you to try a cheaper drug first and have it not work before the plan will cover the one your prescriber wanted. It is not rare: in the February 2026 KFF poll, 29% of insured adults said an insurer had required them to try a lower-cost drug or treatment before covering the one originally recommended, rising to 38% among adults with a chronic condition. Federal Part D rules at 42 CFR 423.120 treat step therapy as a formal utilization-management rule alongside prior authorization, so the same exception and appeal machinery applies to it.
Quantity limits. The plan covers the drug, but only 30 tablets a month, or one inhaler per fill. Going above the limit triggers its own authorization request. Quantity limits, step therapy, and prior authorization flags all live in your plan’s drug formulary, which is worth pulling up before you fill anything expensive.
What Prior Authorization Actually Costs You
The direct cost of prior authorization is zero. The indirect cost is the delay, which acquires a price tag when it pushes you into paying cash, abandoning the prescription, or sitting in a hospital bed waiting on an answer.
The scale is not small. KFF’s analysis of CMS reporting data found Medicare Advantage insurers made nearly 53 million prior authorization determinations in 2024, or 1.7 per enrollee, and denied 4.1 million of them, or 7.7%, up from 6.4% in 2023. In the February 2026 KFF poll, 47% of insured adults said a service, treatment, or medication had been denied or delayed in the past two years, and one in three of those who experienced it said it had a major negative impact on their finances.
If your authorization is stuck and the care cannot wait, the cash market is the fallback. These are published self-pay prices, read September 6, 2026:
| If the plan is stalling on | Cash fallback | Price |
|---|---|---|
| MRI without contrast | Radiology Assist, all-inclusive (scan, read, report) | From $265 |
| CT scan without contrast | Radiology Assist | From $130 |
| Mammogram, screening or diagnostic | Radiology Assist | From $140 |
| Ultrasound, most body parts | Radiology Assist | From $115 |
| X-ray, 2 views | Radiology Assist | From $33 |
| Zepbound 2.5 mg, 1 month | Lilly self-pay tier (plan does not cover it) | $299 |
| Zepbound 5 mg, 1 month | Lilly self-pay tier | $399 |
| Zepbound 7.5 mg and above, 1 month | Lilly self-pay tier | $449 |
Radiology Assist notes that an uninsured patient billed the ordinary way should expect roughly $2,000 for an MRI, which is the spread you are working with. The full picture is in MRI cost without insurance and GLP-1 cost without insurance. Two cautions: money you pay outside the plan generally does not count toward your deductible or out-of-pocket maximum, because no claim is filed, and the Lilly self-pay tiers carry expiration dates, so re-read the page before relying on the number.
There is one more free option people leave on the table. Under 42 CFR 423.120, a Medicare Part D plan must provide a one-time temporary supply of at least an approved month’s worth of a drug during your first 90 days in a new plan, and that requirement explicitly covers drugs on the formulary but flagged for prior authorization or step therapy. Written notice follows within 3 business days. That is a month of breathing room to get the paperwork done. More routes to a lower price are in prescription assistance programs.
Which Plans Require It and Which Rules Apply
Every kind of coverage uses prior authorization, but the rulebook differs, and knowing which one you are under determines what you can demand.
Employer and other ERISA plans. Prior authorization here is a pre-service claim under the Department of Labor claims-procedure regulation at 29 CFR 2560.503-1, which sets both the decision clocks and the appeal rights. States cannot regulate self-funded employer plans, which is why a state prior authorization law may not help you even if you live in that state. Ask your benefits office whether the plan is self-funded or fully insured.
ACA marketplace and other individual plans. Same federal pre-service claim structure, plus whatever your state insurance department adds on top. State add-ons are often stricter than the federal floor.
Medicare Advantage. The most heavily regulated of the group. Under 42 CFR 422.138, prior authorization may only be used to confirm a diagnosis or the medical criteria behind a coverage decision, or to confirm medical necessity. Traditional Medicare barely uses prior authorization at all, which is one of the real differences between the two. See Medicare Advantage vs Original Medicare.
Medicare Part D. Formulary tiers, step therapy, and quantity limits are governed under part 423 and get their own track, called a coverage determination. See Medicare Part D.
Medicaid. Both fee-for-service Medicaid and Medicaid managed care plans are now subject to federal decision deadlines, and states may impose shorter ones.
The 2026 and 2027 rule change. The CMS Interoperability and Prior Authorization final rule, CMS-0057-F, applies to Medicare Advantage organizations, state Medicaid and CHIP fee-for-service programs, Medicaid and CHIP managed care plans, and qualified health plan issuers on the federally facilitated exchanges. Three things matter to you:
- Beginning January 1, 2026, those payers (with marketplace issuers carved out of this one piece) must decide standard requests within 7 calendar days and expedited requests within 72 hours, and they must give a specific reason for any denial regardless of whether it comes by portal, fax, email, mail, or phone.
- Beginning in 2026, they must post prior authorization metrics on their own websites every year by March 31, including approval rates, denial rates, the share approved after appeal, and median decision times.
- Beginning January 1, 2027, they must run a Prior Authorization API that publishes which items and services need authorization, identifies the documentation required, and returns approvals, denials with reasons, or requests for more information electronically.
None of this applies to drugs. Every prior authorization provision in CMS-0057-F explicitly excludes drug coverage, which is why the medication side of the process has changed least.
What to Do If It Is Denied or Delayed
Get the reason in writing. Since 2026 the impacted payers have to give a specific denial reason. That reason is the roadmap: a missing lab value is a resubmission, a step therapy requirement is an exception request, and a “not medically necessary” is a genuine appeal. Your explanation of benefits and the plan’s denial notice should both name it.
Ask for expedited handling if waiting would hurt. Urgent requests run on hour-based clocks instead of day-based ones across every kind of plan. Your doctor’s office has to flag it as urgent, so ask them to.
Appeal, because the odds are genuinely good. KFF found that just 11.5% of denied Medicare Advantage prior authorization requests were appealed in 2024, and 80.7% of the appeals that were filed overturned the denial. Start with how to appeal a health insurance denial and use the template in insurance appeal letter. Medicare has its own five-level ladder, described in Medicare appeal.
Ask your doctor to request a peer-to-peer. It is faster than a written appeal and often resolves the case before one is needed.
Price the cash route in parallel. If the self-pay price is close to what your cost sharing would have been, the authorization fight may not be worth the delay. Providers will negotiate: see how to negotiate medical bills.
Watch the clock. If a Medicare Advantage plan blows its deadline, the missed deadline is itself an adverse determination you can appeal. Part D plans that miss theirs must automatically forward your request to an independent review entity within 24 hours.
The Bottom Line
Prior authorization is the plan’s advance permission, it is required before care rather than after, and an approval is not a promise of payment. It is also mostly granted: Medicare Advantage insurers approved more than 92% of the nearly 53 million requests they decided in 2024. The problems concentrate in the minority that get denied, where about one in nine denials is appealed and roughly four in five of those appeals succeed. If yours is denied, the arithmetic favors appealing. If it is merely slow and the care cannot wait, price the cash alternative in parallel rather than sequentially.