Types of Insurance Denials

Coding Errors 78% success rate

Coding errors are the most straightforward denials to overturn. These occur when the wrong CPT (procedure) code, ICD-10 (diagnosis) code, or modifier is submitted on the claim. Common scenarios include using an outdated code, a typo in the code, using an unlisted code when a specific code exists, or mismatching the procedure code with the diagnosis code.

These denials often appear with language like "the procedure code is not consistent with the diagnosis," "invalid code submitted," or "the modifier is missing or incorrect." Sometimes the provider's billing department submitted the wrong code entirely, and the fix is as simple as resubmitting with the correct one.

Prior Authorization Denials 65% success rate

Prior authorization (PA) denials happen before treatment occurs. Your insurer requires advance approval for certain procedures, medications, or specialist visits, and has determined that the request does not meet their criteria. This is one of the most frustrating denial types because it prevents you from getting treatment you and your doctor agree you need.

These denials typically say something like "the requested service does not meet criteria for prior authorization," "additional information is needed," or "the request has been reviewed and does not meet medical necessity criteria." Sometimes the reviewer is not even a specialist in the relevant field -- under many state laws, you have the right to have your case reviewed by a physician in the same specialty.

Step Therapy and Formulary Denials 60% success rate

Step therapy (also called "fail first") requires you to try cheaper treatments before the insurer will cover the one your doctor prescribed. Formulary denials occur when your prescribed medication is not on the insurer's approved drug list, or is on a higher tier requiring higher copays or prior authorization.

These denials often state "the prescribed medication requires step therapy," "try [alternative drug] first," or "the medication is not on the formulary." The frustration is real: your doctor prescribed a specific medication for a reason, and the insurer is overriding that clinical judgment based on cost.

Medical Necessity Denials 55% success rate

Medical necessity denials are the most common type. The insurer's reviewer has determined that the treatment or service is "not medically necessary" for your condition. This does not mean the treatment is experimental -- it means the insurer does not agree it is needed in your case, based on their clinical criteria.

The denial language typically includes phrases like "does not meet criteria for medical necessity," "the clinical information submitted does not support the need for this service," or "the requested service is not medically necessary based on the information provided." These can be particularly insulting when your doctor has clearly explained why you need the treatment.

The key insight is that "medical necessity" is defined differently by every insurer. Each has its own clinical coverage policies with specific criteria. Your appeal needs to show you meet those specific criteria, not just that the treatment is generally effective.

Out-of-Network Denials 50% success rate

Out-of-network (OON) denials occur when you receive care from a provider not in your insurer's network. However, many OON denials are actually illegal under the No Surprises Act (effective January 2022), which protects patients from surprise out-of-network bills in several key situations.

The No Surprises Act protects you when:

• You receive emergency care at any facility (you cannot be balance billed by OON emergency providers)
• You receive care at an in-network facility from an out-of-network provider you did not choose (anesthesiologist, radiologist, pathologist, etc.)
• You receive air ambulance services from an OON provider

Outside these protections, OON denials are harder to appeal. But there are still arguments: if no in-network provider offers the service within a reasonable distance, most states require the insurer to cover OON care at in-network rates. This is called "network adequacy."

Experimental or Investigational Denials Varies widely

These denials claim that the treatment is "experimental," "investigational," or "not yet proven effective." This is one of the most difficult denial types to overturn because the burden of proof is high. However, insurers sometimes apply this label incorrectly to treatments that are well-established but newer, or that have FDA approval but limited insurer adoption.

A treatment is not truly "experimental" just because it is newer than the alternative. If it has FDA approval, is recommended by major medical societies, and has published clinical evidence, calling it experimental is inaccurate.

Benefit Limit Denials Varies by situation

These denials occur when you have exhausted the benefit limit in your plan -- for example, a maximum number of physical therapy visits per year, a dollar cap on certain services, or a lifetime maximum (though the ACA eliminated lifetime maximums for essential health benefits).

The denial will typically say "benefit maximum reached," "exceeds the plan limit of X visits/services," or "services exceed the annual/lifetime maximum." These are harder to appeal because they are based on plan design rather than clinical judgment.