Pre-Authorization in Health Insurance: What Requires It and Why It Gets Denied

What Prior Authorization Actually Means

Prior authorization is essentially a gatekeeping mechanism built into most commercial health plans. Before your insurer agrees to cover certain services or medications, it wants to confirm the care meets its definition of medically necessary. That review happens before you receive the care — not after.

The process usually starts with your doctor's office submitting a request that includes clinical notes, your diagnosis, and why the specific treatment is appropriate. The insurer's team — typically a nurse reviewer or medical director — evaluates that information against internal coverage criteria.

It's worth understanding that prior authorization is a coverage decision, not a clinical one. Your insurer is determining whether it will pay, not whether the care is right for you. Your doctor makes the clinical call; the insurer decides if it fits within your plan's coverage rules. For a broader overview of how these coverage decisions fit into your overall plan, see how health insurance works.

Services and Medications That Commonly Require It

Not every medical service needs prior authorization, but the list of those that do has expanded in many plans. Common categories include:

• Specialty medications — especially brand-name drugs with generic alternatives available, or high-cost biologics used for conditions like rheumatoid arthritis or Crohn's disease
• Advanced imaging — MRIs, CT scans, and PET scans often require authorization because they are expensive and sometimes ordered when simpler diagnostics could be tried first
• Elective surgeries — joint replacements, bariatric surgery, and spinal procedures are frequently subject to review
• Mental health and substance use treatment — inpatient psychiatric stays and some intensive outpatient programs commonly require approval
• Durable medical equipment — items like CPAP machines, power wheelchairs, and home infusion therapy
• Out-of-network specialist visits — where your plan has any out-of-network coverage at all

Your plan's summary of benefits or formulary (drug list) will identify which services and drugs are flagged. If you're navigating a plan that requires specialist referrals as well, how referral requirements work in gated health plans explains that parallel process.

Why Requests Get Denied — and What to Do

A denial doesn't always mean your insurer thinks the care is unnecessary. The most common reasons for prior authorization denials are procedural and administrative:

• Insufficient documentation — the clinical notes sent didn't include enough detail to meet the insurer's criteria
• Step therapy requirements not met — the plan requires that a less expensive treatment be tried first before approving the requested one
• Service not covered under the plan — the procedure falls outside the plan's covered benefits entirely
• Out-of-network provider — the insurer approved the service but not the specific provider performing it
• Coding errors — an incorrect diagnosis or procedure code on the request form

When a denial arrives, the letter must explain the specific reason and describe your appeal rights. You have two main options: an internal appeal (asking the insurer to reconsider, often with additional documentation from your doctor) and, if that fails, an external review by an independent organization not employed by your insurer.

Keeping thorough records — including submission dates, reference numbers, and the names of anyone you speak with — strengthens your position during an appeal. Ask your doctor to write a letter of medical necessity if one wasn't included in the original submission.

Understanding how your insurer evaluates claims more broadly can also help you anticipate these friction points. What the claims process reveals about a policy is worth reading before you're in a stressful situation.

“The appeals process exists precisely because prior authorization decisions are not always correct on the first pass. Patients and physicians who push back with solid documentation frequently succeed.”

— Karen Pollitz, Senior Fellow, KFF (Kaiser Family Foundation), health policy researcher

How to Reduce the Chance of Delays or Denials

The most practical step is to verify requirements before any non-emergency service is scheduled. Here's a straightforward approach:

1. Call the member services number on your insurance card and ask specifically whether the service or drug requires prior authorization.
2. Confirm your doctor's office has submitted the request and ask for a reference number.
3. Follow up with your insurer a few days later to check the status.
4. Ask your doctor to include thorough clinical notes and documentation supporting the medical necessity of the service.

If you're comparing plans and prior authorization is a concern, questions worth asking before committing to any insurance policy includes coverage and claims questions that can reveal how a plan handles these processes before you're locked in.

Preventive care is generally treated differently — many services are covered without authorization or cost-sharing under ACA rules. Why preventive care is covered differently breaks down where those protections apply and where they don't.

This article is for general informational purposes only and is not a substitute for personalized insurance, financial, or medical advice. Coverage rules, authorization requirements, and appeal rights vary by plan and state. Always consult your insurer's official plan documents and a licensed insurance professional for guidance specific to your situation.