Preauthorization is an approval your insurance company requires before you receive certain medical services, procedures, or medications. Without it, your insurer can refuse to pay the claim or reduce what they cover, leaving you responsible for a larger share of the bill. It’s one of the most common gatekeeping steps in medical billing, and understanding how it works can save you from unexpected costs.
How Preauthorization Works
Before you undergo a specific procedure, start a new medication, or receive certain types of medical equipment, your health plan may require your doctor’s office to submit a request proving the service is medically necessary. This request typically includes your diagnosis, the proposed treatment plan, and supporting clinical documentation. Your insurer then reviews the information and either approves, denies, or requests additional details.
The process happens before care is delivered. Your doctor’s office initiates it, not you, but the consequences of a missing or denied authorization land squarely on your bill. If your plan requires preauthorization for a service and it wasn’t obtained, you may receive only a reduced insurance payment or no coverage at all. That’s true even if the service itself would normally be covered under your plan.
You’ll sometimes see the terms “precertification” and “prior authorization” used interchangeably, and for practical purposes they mean the same thing. Mayo Clinic lists them as synonyms. A related but slightly different concept is “predetermination,” which is your insurer’s advance estimate of whether a service meets their medical necessity criteria. In everyday billing, though, most people encounter all three under the umbrella of preauthorization.
Services That Typically Need It
Not every doctor visit or lab test requires preauthorization. Insurers generally reserve it for higher-cost or more complex care. Common categories include:
- Imaging scans: CT scans, MRIs, and PET scans
- Hospital services: inpatient admissions, outpatient surgeries, and observation stays
- Invasive procedures: colonoscopies, biopsies, and elective surgeries
- Specialty medications: particularly expensive or high-risk prescriptions
- Durable medical equipment: power wheelchairs, lower limb prosthetics, orthotic braces, pneumatic compression devices, and pressure-reducing support surfaces all appear on Medicare’s required prior authorization list
Your specific plan determines what needs preauthorization. Two people with different insurers could need the exact same knee MRI, but only one might need prior approval. Your insurance card, benefits summary, or a call to your plan’s member services line will tell you what applies to your coverage.
Why Insurance Companies Require It
Insurers use preauthorization as a cost-control tool. The stated purpose is to confirm that a proposed service is medically necessary and appropriate before the insurer commits to paying for it. In theory, this prevents unnecessary procedures and steers patients toward equally effective but less expensive alternatives.
In practice, the system creates a significant administrative burden. An AMA physician survey found that medical practices complete an average of 39 prior authorizations per physician, per week. That volume translates into dedicated staff time, phone calls, fax submissions, and follow-ups that pull resources away from direct patient care. Among physicians surveyed, 93% reported that the prior authorization process delays access to necessary care for their patients.
What Happens When a Request Is Denied
A denial doesn’t always mean the service isn’t covered. It often means the insurer needs more information or disagrees with the clinical justification provided. The most common reasons for preauthorization denials include: the insurer determining a treatment isn’t medically necessary, disputes over whether mental health or substance abuse treatment meets plan criteria, disagreements about the appropriate care setting (such as home care versus hospitalization), and use of out-of-network providers.
If your preauthorization is denied, you have the right to appeal. The first step is an internal appeal, where your insurer re-examines the decision, often with additional documentation from your doctor. If the internal appeal is also denied, you can request an external review by an independent review organization (IRO). This is a separate entity with no ties to your insurance company, and their decision on whether the insurer should cover your claim is typically binding. Your insurer is required to tell you how to initiate both levels of appeal when they send a denial notice.
What Skipping Preauthorization Costs You
If a required preauthorization wasn’t obtained before you received care, the financial consequences vary by plan but are rarely good. Some insurers deny the claim entirely, meaning you owe the full cost. Others apply a penalty by covering a smaller percentage than they normally would. In some cases your provider’s office absorbs the loss as a write-off, but that’s not guaranteed and you shouldn’t count on it.
Emergency care is generally an exception. Most plans waive preauthorization requirements for true emergencies, though they may require notification within a set window afterward (often 24 to 72 hours). If you’re admitted to the hospital through the emergency department, your insurer usually expects a retroactive authorization request for the inpatient stay within that same timeframe.
Electronic Prior Authorization
Traditionally, prior authorization involved phone calls, faxes, and long waits. A growing number of health systems now use electronic prior authorization (ePA) systems built directly into the electronic health records that doctors already use for prescribing and charting.
With ePA, the system checks your insurance formulary at the moment your doctor writes a prescription. If prior authorization is required, the prescriber gets an immediate alert within their workflow rather than waiting for a pharmacy to reject the prescription days later. The doctor can then complete the authorization form electronically and send it to the insurer for review, all without leaving the system. If approved, the pharmacy fills your prescription normally. If denied, the insurer sends the denial and any alternative medication suggestions back through the same system so your doctor can adjust quickly.
Sutter Health, a large integrated health system in northern California, was among the early adopters of ePA embedded in its Epic electronic health record system. While ePA doesn’t eliminate the authorization requirement, it removes some of the delays and communication breakdowns that make the traditional process so frustrating for patients and providers alike.
How to Protect Yourself
The single most useful thing you can do is ask about preauthorization before any scheduled procedure, new medication, or equipment order. Call the number on your insurance card and ask whether the specific service requires prior approval. Don’t assume your doctor’s office has already handled it, especially if you’re seeing a new specialist or switching plans.
If your doctor’s office tells you they’ve submitted a preauthorization request, ask for the reference number and approval status before your appointment date. Approvals sometimes expire after a set number of days, so a surgery that gets rescheduled may need a new authorization. Keep records of every approval, including the date, reference number, and what exactly was approved. If a billing dispute arises months later, that documentation is your best defense.