A prior authorization is an approval your health insurance plan requires before it will cover a specific service, procedure, or prescription. Without this approval, your insurer can refuse to pay, leaving you responsible for the full cost. Not every medical service needs one, but enough do that most people eventually encounter the process.
How Prior Authorization Works
When your doctor recommends a treatment that falls on your insurer’s prior authorization list, the doctor’s office submits a request to your insurance company before the treatment happens. The request includes clinical documentation explaining why the service is medically necessary for you. Your insurer reviews this information and either approves, denies, or asks for more details.
You might also hear this process called pre-certification, pre-authorization, or prior approval. They all mean the same thing: your insurer wants to review and sign off on a service before you receive it.
Why Insurers Require It
The primary reason is cost control. Insurers use prior authorization to steer patients toward less expensive options when they exist, such as generic medications instead of brand-name drugs, or in-network facilities that have negotiated lower rates. They also use the process to flag care they consider unnecessary, denying requests when the submitted documentation doesn’t justify the treatment.
Prior authorization can also serve as a safety check. Treatments with higher complication risks, like opioid prescriptions, often require approval. If a drug is contraindicated for your specific health situation, the review process can catch that before you’re exposed to harm. The system originally developed around experimental drugs and treatments that were both expensive and unproven, and it has expanded significantly since then.
Services That Commonly Need Approval
The specific list varies by insurer and plan, but certain categories show up frequently. Advanced imaging (MRIs, CT scans), specialty medications, and elective or semi-elective surgeries are common triggers. For Medicare specifically, CMS requires prior authorization for outpatient procedures including spinal fusion with disc removal, implanted spinal neurostimulators, facet joint interventions, vein ablation, and certain cosmetic-adjacent procedures like eyelid surgery and rhinoplasty.
Your plan’s formulary (its list of covered drugs) will usually indicate which medications require prior authorization. High-cost biologics, specialty drugs for chronic conditions, and controlled substances are frequent candidates. If you’re unsure whether a prescribed service needs approval, your insurance company’s member services line or your doctor’s billing office can tell you before treatment begins.
How Long the Process Takes
Federal rules currently require Medicaid managed care plans to make standard prior authorization decisions within 14 calendar days. Urgent or “expedited” requests must be decided within 72 hours. Many states have set shorter windows: as of mid-2024, half of states with Medicaid managed care programs required standard decisions within 7 days or less, and about a third required expedited decisions faster than 72 hours.
Starting January 2026, a new federal rule will shorten the standard decision timeframe to 7 calendar days across the board for affected payers. The same rule requires insurers to build electronic systems for submitting and tracking prior authorizations by January 2027, which should reduce the back-and-forth that currently slows many requests.
Private insurance timelines vary by state and plan. In practice, straightforward requests for common services often come back within a few days. Complex requests, especially those requiring additional documentation, can stretch to weeks.
What Happens When a Request Is Denied
Denials are not uncommon, and they’re not always the final word. When your insurer denies a prior authorization, you have the right to appeal. Most states provide three levels of appeal: two internal reviews handled by the insurance company, followed by an external review conducted by an independent party.
A significant portion of denials get overturned when challenged. CMS data from fiscal year 2024 shows that appeal overturn rates varied widely depending on the type of service. For durable medical equipment like wheelchairs and oxygen supplies, about 38% of appealed claims were overturned. For home health services, the overturn rate reached nearly 52%. The most common reason claims were overturned on appeal was the submission of additional documentation that wasn’t included in the original request.
That last point is worth noting. Many denials happen not because the treatment is genuinely unnecessary, but because the initial paperwork was incomplete. If your prior authorization is denied, ask your doctor’s office what additional records or clinical notes could strengthen the case before filing an appeal.
What You Can Do to Avoid Delays
Start by knowing your plan. Your insurer’s website or member handbook lists which services require prior authorization. Finding out a procedure needs approval after it’s already been scheduled can push your treatment back by weeks.
When your doctor orders something that requires authorization, confirm that the request has actually been submitted. Requests sometimes fall through the cracks between your doctor’s office and the insurer, and you may not hear about the delay until it’s already cost you time. Ask for a reference or tracking number so you can follow up directly with your insurance company.
If your situation is urgent, make sure your doctor’s office requests an expedited review rather than a standard one. The difference between a 72-hour decision and a 14-day decision can matter enormously when you’re in pain or your condition is worsening. Your doctor can note the clinical urgency in the submission, which may speed things along.
Keep copies of everything: the original request, any denial letters, and all communication between your doctor’s office and your insurer. If you end up needing to appeal, having a clear paper trail makes the process faster and stronger.