What Is Prior Authorization in Health Insurance?

Updated: April 7, 2026

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Key Takeaways
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Prior authorization is your insurer's advance approval for certain procedures, medications or services before you receive them.

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Insurers must decide within 72 hours for urgent requests and seven days for standard requests under CMS-0057-F (Medicare Advantage, Medicaid managed care and federal exchange QHP issuers).

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A missed prior authorization results in a full claim denial, even when the service is a covered benefit under your plan.

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You can appeal a prior authorization denial within 180 days of receiving the denial notice.

What Is Prior Authorization?

Prior authorization is your health insurer's advance approval before you receive a given service, procedure or medication. Without it, your plan can deny the entire claim and leave you with a bill for thousands of dollars, even when the service is a covered benefit. 

Prior authorization applies to routine services, not only experimental treatments. MRIs, specialty prescriptions, and outpatient surgery your doctor schedules months in advance all require it. Your insurer evaluates whether the requested service meets its medical necessity criteria and coverage rules.

Review your plan's summary of benefits and coverage (SBC) before enrolling to see which services require prior authorization. The list is plan-specific and varies by insurer.   

  • Prior authorization is separate from a referral. A referral (required on some HMO and POS plans) permits you to see a specialist. Prior authorization is approval of a given service the specialist wants to provide. You may need both for the same visit.
  • Approval doesn't guarantee payment. Your insurer can still deny the final claim if the service provided differs from what was authorized, or if your coverage lapses between approval and the appointment.
  • Emergency services don't require prior authorization. ACA rules require your plan to cover emergency care without advance approval, regardless of network status.

Compare health insurance plans by reviewing the prior authorization list in each SBC before you enroll.

How Does Prior Authorization Work Step by Step?

Prior authorization starts when your provider identifies a service, drug or procedure that your plan requires advance approval for. Your provider and insurer handle the back-and-forth, but you need to confirm approval before your appointment. Skip that step and you risk a full claim denial, even for covered services.

  1. 1

    Your Provider Identifies the Requirement

    Your doctor, specialist or prescriber checks whether your plan requires prior authorization for the recommended service. Requirements differ by insurer and plan, so a procedure may need approval under one plan but not another. Your provider’s billing office usually handles this check.

  2. 2

    Your Provider Submits the Request With Clinical Documentation

    Your provider, not you, sends the prior authorization request to your insurer. The submission includes clinical notes, diagnosis codes and documentation that supports medical necessity. Complete and accurate records help move the request forward faster. Missing details often lead to delays.

  3. 3

    Your Insurer Reviews the Request

    Your insurer’s clinical team reviews the request against its medical necessity standards and coverage rules. Under the CMS Interoperability and Prior Authorization Final Rule (CMS-0057-F), Medicare Advantage organizations, Medicaid managed care plans and qualified health plan issuers on the federal exchange must issue decisions within 72 hours for urgent requests and seven calendar days for standard requests. 

    State-based exchange issuers and other plans not subject to this rule may follow the 15-day timeframe for non-urgent requests under earlier ACA rules.

  4. 4

    You Receive an Approval or Denial

    Your insurer sends the decision to both you and your provider. If your provider doesn't respond to a request for more information, the review timeline starts over. Approved authorizations include an expiration date, often 60 to 120 days from the decision.

  5. 5

    Confirm Authorization Before Your Appointment

    Contact your insurer to confirm the authorization was received, approved and still valid before your appointment. Don't rely on your provider to track the outcome. This step helps avoid unexpected denials after care is provided.

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PRIOR AUTHORIZATION WARNING

Your provider submits the prior authorization request, but your insurer sends the decision to you and not always to your provider. Call your insurer to confirm approval status, the service code authorized and the expiration date before scheduling. Proceeding without confirmed approval means your plan may deny the claim regardless of whether the service is a covered benefit.

Which Health Care Services Require Prior Authorization?

Prior authorization requirements vary by plan, not by plan type. Under CMS-0057-F, insurers must post a public list of all services requiring prior auth beginning with 2026 plan year reporting, but requirements still vary by plan until that data is uniformly available. 

Commercial plans set prior authorization lists at the insurer level: two HMO plans from different insurers can have different prior auth requirements for the same procedure.

Service Category
Common Examples
Notes

Advanced diagnostic imaging

MRI, CT scan, PET scan

Among the most frequently authorized services. Your plan's SBC specifies which imaging types trigger the requirement.

Specialty and brand-name prescription drugs

Biologics, specialty-tier medications, many brand-name drugs

A drug can be on your formulary and still require prior authorization. Approval is separate from formulary tier.

Inpatient hospital admissions

Non-emergency surgery, scheduled hospitalization

Nearly universal across commercial plans for non-emergency admissions. Emergency admissions are exempt under ACA rules.

Outpatient procedures

Joint replacement, bariatric surgery, cardiac procedures

Specific procedure codes trigger the requirement. Your provider can confirm which CPT codes require prior authorization on your plan.

Behavioral health and substance use services

Intensive outpatient programs, residential treatment, some therapy types

Federal mental health parity rules prohibit insurers from applying prior authorization requirements more stringently to behavioral health than to comparable medical or surgical benefits. HMO plans layer this requirement on top of the referral step.

What Happens If You Skip Prior Authorization?

If you don't go through prior authorization, it gives your insurer grounds to deny the entire claim. Not reduce the payment, but deny it in full. You would owe the full billed amount, and this applies even when the service itself is a covered benefit under your plan. The denial occurs after care is delivered, which means you may receive the bill before you know authorization was missing.   

Emergency services are exempt from prior authorization under ACA rules, but urgent care isn't always exempt. Confirm your plan's retroactive authorization policy before assuming urgent care falls outside the requirement. 

One gap many plan members overlook: prior authorization approval for a service does not make an out-of-network provider in-network. Your plan may approve the service but pay only at in-network rates, leaving you with a balance bill for the co-insurance and copay difference. 

Confirm both prior auth status and provider network status before every appointment.

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HOW CAN YOU SPEED UP PRIOR AUTHORIZATION APPROVAL?

Most prior authorization delays are avoidable. Your provider controls submission quality, but a few actions on your end reduce waiting time.   

  • Check with your provider's billing office that the request went out the same day as your appointment or prescription.
  • Get a copy of the submitted clinical documentation and make sure it lists your diagnosis code, treatment history and service code.
  • Call your insurer 48 hours after submission to confirm they received it and catch any missing information before the review window closes.
  • For urgent situations, ask your provider to request expedited review and put the clinical reason for urgency in writing on the submission.

Before choosing among affordable plan options, compare prior auth requirements across plans in the SBC. Plans with shorter standard review windows list this in plan documents.

Services Most Likely to Trigger a Prior Authorization Denial

Prior authorization denials aren't evenly distributed across service types. Certain categories account for the majority of disputes between plan members and insurers. Knowing which services draw the most scrutiny lets you confirm approval status before the appointment, not after the bill arrives.

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    Specialty Drug Requiring Advance Approval

    Your insurer must approve specialty medications before your pharmacy fills them, even when the drug is on your plan's formulary. Your prescriber submits a prior authorization request with documentation of medical necessity. 

    Without approval, your pharmacy won't dispense the medication at the plan's covered rate. Specialty drugs can cost thousands of dollars per fill, and approval isn't retroactive once the fill is dispensed.

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    Inpatient Stay Denied After Admission

    For non-emergency hospitalizations and scheduled surgeries, your provider submits prior authorization 72 hours to two weeks in advance. Two outcomes apply when authorization fails:

    • If denied after admission, or if your provider failed to submit before the procedure, you may owe the full cost of the stay.
    • Inpatient costs routinely exceed tens of thousands of dollars. Request written confirmation before you check in.
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    Specialist Procedure Not Pre-Approved

    Many plans require prior authorization for specific specialist procedures regardless of whether a referral was already issued. An orthopedic surgeon performing a covered knee replacement still needs prior authorization submitted and approved before the procedure date. 

    Your specialist's office is responsible for submitting the request. Confirm the request was submitted and approval was received before your procedure.

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    Behavioral Health Visit Subject to Stricter Review

    Federal mental health parity rules prohibit insurers from applying prior authorization to behavioral health benefits more stringently than to comparable medical and surgical benefits. Two paths apply depending on your plan:

    • If your plan applies prior authorization equally to behavioral health and medical visits, the requirement is permissible.
    • Plans that require prior authorization for outpatient mental health therapy but not for equivalent medical visits are in violation. Report it to your state insurance commissioner or the U.S. Department of Labor.

How to Appeal a Prior Authorization Denial?

Any ACA-compliant plan member has the right to appeal a prior authorization denial. The process has two stages: an internal appeal through your insurer and, if that fails, an external review by an independent organization. 

Deadlines are strict. Missing the 180-day internal appeal window forfeits your right to challenge the denial under federal ACA protections.

  1. 1

    Request the Denial Reason in Writing

    Your insurer must give you a written explanation for the denial. Under CMS-0057-F, starting in 2026, impacted payers must include a clear reason for any denied prior authorization. Read the denial letter closely. The reason listed determines your appeal approach and the documentation you need.

  2. 2

    Ask Your Provider for a Letter of Medical Necessity

    Request a detailed letter from your treating physician that explains why the service is medically necessary for your condition. This is the most important document in your appeal. Ask for it as soon as you receive the denial. The letter should respond directly to the insurer’s stated reason.

  3. 3

    File Your Internal Appeal Within 180 Days

    Send your appeal to your insurer in writing. Include your name, claim number, health insurance ID, your provider’s letter and any supporting clinical records. Keep copies of everything you submit. Your insurer must respond within 30 days for standard pre-service denials and within 72 hours for urgent cases.

  4. 4

    Request an External Review if the Internal Appeal Is Denied

    If your insurer upholds the denial, you can request an external review by an independent organization. Standard reviews take up to 45 days. Expedited reviews are completed within 72 hours. Your insurer must follow the reviewer’s decision. If the federal review process through HHS applies, you will not be charged.

  5. 5

    File a Complaint With Your State Insurance Department if Needed

    If the denial appears to violate your plan terms or federal mental health parity rules, contact your state’s Department of Insurance. Some states offer Consumer Assistance Programs that can file an appeal on your behalf at no cost. Missing the 180-day deadline means you lose the right to appeal.

When Does Prior Authorization Most Affect Your Coverage Decisions?

Prior authorization requirements are set at the insurer level, not the plan-type level: two plans of the same type (both HMOs, both PPOs) can have different prior authorization lists. This fact changes how you compare plans at open enrollment. The SBC lists which services require prior authorization for that specific plan.

Scenario
Prior Authorization Impact
What to Check

You take specialty or biologic medications regularly.

High. Most commercial plans require prior authorization for specialty-tier drugs on every formulary tier. Approval isn't guaranteed and may require step therapy (trying a lower-cost drug first).

Confirm your specific medications' prior authorization status in the plan's drug coverage document before enrolling, not only the formulary tier.

You have a condition likely to require imaging, surgery or specialist procedures.

High. MRIs, CT scans, joint replacements and cardiac procedures require prior authorization on most plans. HMO plans add a referral requirement on top of prior authorization, creating a two-step process.

Review the plan's prior authorization list in the SBC. Confirm your primary care provider and likely specialists are in-network before enrolling.

You're choosing between an HMO and a PPO at open enrollment.

Moderate. Both plan types use prior authorization for the same service categories, but PPO plans give you out-of-network access as a fallback if an in-network prior auth is delayed. An HMO and a PPO carry the same prior authorization requirements for most service categories, but the network restriction differs.

Review the SBC's prior authorization list for each plan alongside the premium costs side by side.

You use primarily preventive care and generic prescriptions.

Low. ACA-compliant plans cover all preventive services at no cost without prior authorization when received from an in-network provider. Generic drugs on lower formulary tiers rarely require prior auth.

Confirm your preventive care providers are in-network. Prior authorization becomes relevant if your health situation changes during the plan year.

You receive emergency care.

None for the emergency itself. ACA rules require your plan to cover emergency services without advance approval regardless of network status.

Understand the distinction between emergency care and urgent care. Urgent care may require prior authorization depending on your plan.

What Prior Authorization Means: Bottom Line

Prior authorization is your insurer's advance approval for certain services, procedures and medications. Skipping it gives your insurer grounds to deny the full claim. 

Under CMS-0057-F, payers must publish prior authorization lists annually and state a clear reason for every denial. Appeal rights run 180 days from the denial notice and an external reviewer's decision is binding.

Prior Authorization in Health Insurance: FAQ

Prior authorization raises a lot of questions. The answers below cover approval timelines, denial scenarios and how requirements differ across plan types:

Does prior authorization guarantee my insurer will pay the claim?

What's the difference between prior authorization and a referral?

Does prior authorization apply to prescription drugs the same way it does to medical services?

What happens if my prior authorization expires before I receive the service?

Does prior authorization apply in emergencies?

Is prior authorization required for mental health therapy on ACA plans?

About Mark Fitzpatrick

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Mark Fitzpatrick, a Licensed Property and Casualty Insurance Producer, is MoneyGeek's resident Personal Finance Expert. He has analyzed the insurance market for over five years, conducting original research for insurance shoppers. His insights have been featured in CNBC, NBC News and Mashable.

Fitzpatrick holds a master’s degree in economics and international relations from Johns Hopkins University and a bachelor’s degree from Boston College. He's also a five-time Jeopardy champion!

He writes about economics and insurance, breaking down complex topics so people know what they're buying.

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