CARC 20: This injury/illness is covered by the liability carrier
Your health insurer says another party's liability insurance — like an auto or homeowner's policy — should pay for this care.
What this means for your claim
When an injury results from an accident where someone else may be at fault, the liability carrier (for example, the at-fault driver's auto insurance) is often the primary payer. Your health plan can deny on this basis until the liability claim is resolved.
What to do next
- 1
If a liability claim is open (auto accident, slip-and-fall), provide your health insurer with the liability carrier's claim information.
- 2
If no liability coverage applies, write to your health insurer explaining that there is no third-party carrier and request the claim be processed under your health plan.
- 3
Ask your provider to hold billing while the correct payer is determined, and keep records of all correspondence.
How to handle a non-covered or denied service
Non-covered codes mean the insurer is declining to pay — either because the plan excludes the service, because medical necessity wasn't established, or because a requirement like prior authorization or timely filing wasn't met. These are the adjustments most worth contesting, because a denial is not the final word: a large share of denials are overturned on appeal when the patient or provider supplies the right documentation.
Find the exact reason for the denial in writing
"Not covered" is a category, not an explanation. Call your insurer and ask specifically why: Is the service excluded from your plan? Was it deemed not medically necessary? Was prior authorization missing? Was the claim filed late by the provider? The precise reason determines who fixes it and how.
Decide whether it's the provider's error or a true plan exclusion
If the problem is a missing prior authorization, a coding error, or late filing, that is usually the provider's responsibility — and in many states they cannot bill you for their own administrative mistakes. If the service is genuinely excluded from your plan, your path is an appeal or financial assistance, not a billing correction.
Gather support for medical necessity before you appeal
When a denial is based on medical necessity, ask your treating physician for a letter of medical necessity and the clinical notes that justify the service. Insurers overturn a meaningful portion of these denials once the supporting documentation is in front of a reviewer.
Your appeal rights for CARC 20
You have a federally protected right to appeal a denial. Request the insurer's full reason and your plan's appeal deadline in writing, then file an internal appeal with your supporting documents. If the internal appeal is denied, you can request an independent external review — a reviewer with no financial stake in the outcome. If the service was an emergency or from an out-of-network provider at an in-network facility, the federal No Surprises Act may also protect you from balance billing.
Have more codes on your EOB?
Upload your full Explanation of Benefits and our analyzer will identify every adjustment code, explain each one in plain English, and flag anything worth disputing.
Analyze My EOB Free →