US Healthcare · Bills & Rights
Prior Authorization and Referrals
What prior authorization is, which services require it, how to appeal a denial, and how HMO referral rules differ from PPO plans.
Patients who have been told a service or medication requires prior authorization, or who are on an HMO and need to understand the referral process before seeing a specialist.
Prior authorization and referrals are two distinct gatekeeping mechanisms in US health insurance. Both can affect whether and how much your insurance will pay for care. Understanding how each works — and how to navigate the process when one is required — can prevent delayed care and unexpected bills.
What prior authorization is and why it exists
Prior authorization (also called precertification, predetermination, or pre-approval) is a requirement that your insurance company approve certain medical services, procedures, or drugs before you receive them. Without this approval, the insurer may decline to cover the cost.
Insurers use prior authorization to review whether a proposed service is medically necessary according to their clinical criteria and whether a less expensive alternative should be tried first. Critics argue it delays care and creates administrative burden for providers and patients alike; federal and state legislators have been working to streamline and limit the scope of prior authorization requirements, particularly for Medicare Advantage plans.
Services commonly requiring prior authorization include:
- Elective surgeries and procedures
- Advanced imaging (MRI, CT scans)
- Specialty medications, particularly high-cost biologics
- Inpatient hospital admissions (non-emergency)
- Extended physical therapy or rehabilitation
- Durable medical equipment (wheelchairs, CPAP devices)
- Home health services
Who initiates prior authorization
Responsibility for requesting prior authorization generally falls on the ordering provider — the doctor or provider who is prescribing or recommending the service. The provider’s office submits a prior authorization request to your insurer, typically with clinical documentation supporting the medical necessity of the service.
As a patient, you play a supporting role: making sure your provider knows your specific insurance plan and plan name (not just the insurer) so they submit the request to the right entity, providing complete insurance information, and following up with both the provider and insurer if you have not received a decision by the expected date.
Understanding denials and how to appeal
When a prior authorization is denied, the insurer must notify you and your provider in writing with the reason for the denial. Common reasons include:
- The service does not meet the plan’s medical necessity criteria
- Step therapy requirements were not met (must try a lower-cost option first)
- The service is excluded from your plan’s covered benefits
- The clinical documentation was insufficient or missing
You have the right to appeal any prior authorization denial. The internal appeal process is the first step: you or your provider submits a request for reconsideration with additional clinical documentation. If the internal appeal is denied, you can request an external review by an independent third party — this right is protected by federal law for most plans.
In urgent situations where waiting for a standard decision could harm your health, you can request an expedited prior authorization. Insurers must respond to urgent requests within a shorter timeframe than standard requests.
How the HMO referral process works
In an HMO plan, your primary care physician (PCP) is the gateway to specialist care. If your PCP determines that you need to see a specialist, they issue a referral — a formal order or recommendation that authorizes you to see a specific specialist or type of specialist and that the HMO will cover. Without that referral, a specialist visit typically will not be covered.
The referral may be for a specific specialist by name or for a category of specialist (such as a cardiologist or orthopedist) — the rules vary by plan. Some HMO plans allow self-referrals for specific categories such as obstetrics or mental health. Ask your insurer for specifics.
Referrals may have time limits (valid for a certain number of visits within a defined period) and may specify in-network providers only. If you need ongoing specialist care, your PCP may need to issue repeat referrals.
Prior authorization and referrals in PPO plans
PPO plans do not generally require referrals to see specialists, which is one of the primary reasons people choose them over HMOs. However, PPO plans may still require prior authorization for specific services or procedures regardless of whether a referral is needed.
The absence of a referral requirement does not mean your plan will automatically cover any specialist you see. The specialist must still be in-network for in-network cost-sharing to apply, and any services the specialist orders may be subject to their own prior authorization requirements.
Keeping records
Always document prior authorization decisions. When authorization is approved, save the authorization number and the service or drug it covers. If the service changes in any way — the dates shift, the procedure evolves — confirm with your insurer whether the original authorization still applies. Billing errors can occur when services are performed after an authorization expires or for a slightly different procedure than what was authorized.
Comparing standard and expedited prior authorization timelines
The timelines below reflect federal requirements for most ACA-compliant plans; state laws and individual insurer policies may be stricter.
| Element | Standard request | Expedited (urgent) request |
|---|---|---|
| Insurer decision window | Up to 3 business days for concurrent review; 15 days for prospective (non-urgent) reviews | 72 hours or fewer after the request is received |
| When to use | Elective or scheduled procedures where delay does not harm health | When waiting for standard review could seriously jeopardize health or ability to function |
| How to request | Provider submits documentation through insurer’s portal or by phone | Provider or patient explicitly designates the request as urgent with supporting clinical documentation |
| Required written notice | Yes — approval or denial with stated reasons | Yes — within the expedited timeframe |
| Appeal if denied | Internal appeal typically within 30–60 days of denial; external review available if internal fails | Expedited internal appeal available; expedited external review available if health urgency continues |
What this looks like in practice
Imagine Sandra, who is on an HMO plan. Her primary care doctor recommends an MRI of her knee after a significant sports injury. The doctor’s office submits a prior authorization request with clinical documentation to her insurer.
Three days later, Sandra receives a written denial. The stated reason is that the clinical criteria for advanced imaging have not been met — she has not yet completed a course of physical therapy. This is a step therapy requirement, sometimes called fail-first.
Sandra’s doctor disagrees and files an internal appeal, submitting additional documentation explaining why physical therapy is not clinically appropriate given the nature of the injury. The insurer’s medical reviewer upholds the denial.
Sandra then requests an external review. An independent review organization — with no financial interest in the outcome — evaluates the clinical evidence. After reviewing Sandra’s medical records and her doctor’s supporting documentation, the external reviewer overturns the insurer’s decision. The MRI is approved.
The entire process took approximately three weeks. Throughout, Sandra documented every communication: she recorded the date and name of each person she spoke with, saved every written letter and email, and noted the authorization case number. That paper trail was central to the successful external review.
Step by step: requesting prior authorization
- When your provider recommends a service, ask their office whether it requires prior authorization under your specific plan. Provide them with your complete insurance information — insurer name, plan name, group number, and member ID.
- Ask the provider’s office to confirm they have submitted the authorization request and to share the expected decision date or case reference number with you.
- Follow up if you have not received a decision by the expected date. Call your insurer’s member services line and provide the case number to check the status.
- When authorization is approved, request written confirmation that includes the authorization number, the specific service or drug covered, the approval period or expiration date, and any conditions attached.
- Save that written confirmation. If the authorization is approved for a specific procedure or date range, do not assume it extends to related services or later dates without confirming with your insurer.
- If the request is denied, ask for the written denial notice, which must state the reason and your appeal rights. Start the internal appeal process as quickly as possible — deadlines apply.
- If the internal appeal is denied, request external review. The denial letter or your insurer’s appeal instructions will explain how to submit. An independent organization will review the clinical evidence and issue a binding decision.
- For situations where delay could harm your health, explicitly ask your provider or insurer to process the request as an expedited authorization from the beginning.
Documents and terms you will see
When navigating prior authorization and referrals, you will encounter the following terms in your plan documents and insurer communications.
- Prior authorization — approval required from your insurer before certain services, procedures, or drugs will be covered
- Referral — a formal recommendation from your primary care physician authorizing a specialist visit under an HMO plan
- Step therapy — a requirement to try lower-cost treatments before a preferred or higher-cost option is approved
- Denial notice — a written notice that a prior authorization or claim was denied, including the reason and your appeal rights
- Internal appeal — a reconsideration request submitted to your insurer, the first step when challenging a denial
- External review — an independent third-party review of a denial, with results that are binding on your insurer
- Appeal — a formal challenge to a coverage decision made by your insurance plan
Key terms
| Term | Plain meaning | Glossary |
|---|---|---|
| Prior authorization | Approval from your insurer required before certain services, drugs, or procedures are covered | → |
| Referral | A formal recommendation from your primary care doctor for you to see a specialist | → |
| HMO | Health Maintenance Organization — requires referrals from a PCP to see specialists | → |
| PPO | Preferred Provider Organization — allows direct specialist access without a referral | → |
| Step therapy | Requirement to try lower-cost treatments before a higher-cost option is approved | → |
Common questions
- How do I know if a service requires prior authorization?
- Your insurer publishes a list of services that require prior authorization. You can find it on the insurer's website, in your plan documents, or by calling member services. The ordering provider — the doctor who prescribes or recommends the service — is usually responsible for submitting the prior authorization request, not the patient.
- What happens if I get care without required prior authorization?
- If you receive a service that required prior authorization and did not get it in advance, the insurer may deny the claim entirely or pay only a reduced amount. You would then be responsible for the balance. In some cases you can appeal retroactively, but this is not guaranteed. For scheduled (non-emergency) care, always confirm whether authorization is needed first.
- How long does prior authorization take?
- Timelines vary by insurer and urgency. For routine requests, insurers typically have several business days to respond under state and federal rules. For urgent requests involving a patient's health, the timeframe is shorter. Insurers must notify you of decisions in writing and provide the reason for any denial.
- What is step therapy and can it be waived?
- Step therapy (also called fail-first) requires that you try one or more lower-cost treatments before your insurer will approve coverage of a preferred or higher-cost treatment. Many states have laws that allow physicians to request a step therapy exception or waiver when clinical reasons make the required first step inappropriate for a patient. Contact your insurer or state insurance commissioner for specifics.
- Do I need a referral for every specialist visit?
- Only if your plan requires it. HMO plans generally require a referral from your PCP before covering a specialist visit. PPO and EPO plans typically do not require referrals. If you are on an HMO and see a specialist without a referral, the insurer may deny coverage for that visit.
- What is an expedited prior authorization and when should I request one?
- An expedited (urgent) prior authorization is a faster review reserved for situations where waiting for a standard decision could seriously jeopardize your health. Federal rules require insurers to respond to expedited requests within 72 hours (or sooner under some state laws), compared with several business days for standard requests. Your provider typically requests expedited status by documenting the clinical urgency in the submission.
- What must a denial notice include?
- When an insurer denies a prior authorization or claim, the written denial notice must state the specific reason for denial — including any clinical criteria applied — the date of the decision, and the steps and deadlines for filing an appeal. For prior authorization denials, it must also include the clinical basis used to evaluate the request. Incomplete or vague denial notices can themselves be grounds for an appeal.
- How does an external review differ from an internal appeal?
- An internal appeal is a reconsideration request submitted to your insurer. The insurer reviews the decision using its own clinical staff. An external review is conducted by an independent review organization that has no financial relationship with the insurer. External reviewers have the final say, and their decision is binding on the insurer. The right to external review is guaranteed by federal law for most ACA-compliant plans.
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Last reviewed: September 2026