CO-45 Denial Code: Charge Exceeds Fee Schedule

The official definition

“Charge exceeds fee schedule/maximum allowable or contracted/legislated fee arrangement”

That is the verbatim definition of CARC 45 from the X12 Claim Adjustment Reason Code set, the standardized codes every insurer uses on EOBs and remittance advices. The letters in front of the number are the group code. CO: Contractual Obligation: an adjustment between the provider and the insurer. An in-network provider should not bill you for CO amounts.

What it means in plain English

The provider charged more than the insurer allows for this service. For an in-network provider, this is the routine contractual discount: the provider agreed to accept the insurer's rate, and the CO-45 amount is written off. It only becomes your problem when the provider is out-of-network, where the difference can turn into balance billing.

What to check on your EOB

• The group code. CO-45 from an in-network provider is a normal adjustment. You should never be billed for it.
• Whether the provider is in-network. If they are and your bill includes the CO-45 amount, the provider is violating their contract with the insurer.
• For out-of-network care: whether the service was emergency care or delivered by an out-of-network provider at an in-network facility. The No Surprises Act may limit what you owe to in-network cost-sharing.

What to do next

1. In-network: if the provider bills you for the CO-45 amount, call their billing office and point out that the adjustment is a contractual obligation they agreed to absorb.
2. Out-of-network: check No Surprises Act and state surprise-billing protections before paying anything.
3. If protections don't apply, negotiate: ask the provider to accept the insurer's allowed amount or offer a discount or payment plan.

Who's responsible

Provider (in-network); you, if out-of-network balance billing appears. Most denials carry a clear owner. Knowing whether the fix belongs to you, your doctor, or the billing office is half the battle. If it's the provider's error, you should not be paying for it.

Want the fundamentals first? Start with how to read an EOB and the 7 most common billing errors. This page is general information about standardized denial codes, not legal or medical advice.