CO-97 Denial Code: Bundled Into Another Service

The official definition

“The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated”

That is the verbatim definition of CARC 97 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 insurer says this service is already included in what they paid for another service: they're treating the two as one bundle rather than separate charges. Often this is correct (NCCI bundling rules exist for exactly this reason). But when the two services were genuinely distinct (different sites, different sessions, different purposes), the claim needs a modifier and a second look.

What to check on your EOB

• Which service this one was bundled into. Compare the line items on your EOB.
• Whether the services were truly distinct: different anatomical sites, different purposes, or separate sessions on the same day.
• Whether a modifier (59 or the X modifiers) appears on the claim. Its absence is often why a legitimately separate service got bundled.

What to do next

1. If the bundling looks appropriate (the second charge really was a component of the first), no action is needed, and you should not be billed for the CO-97 amount by an in-network provider.
2. If the services were genuinely separate, ask the provider's billing office to review the modifiers and resubmit with documentation.
3. For surgical claims, the provider should appeal with operative notes showing why the services shouldn't be bundled.

Who's responsible

Provider. 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.