CO-24 looks like a routine contractual write-off, but it is different from every other CO code. It does not tell you a charge exceeded the fee schedule or that a service was bundled. It tells you the payment model is wrong: "charges are covered under a capitation agreement." The payer is saying it already pays you a fixed per-member amount for these services and will not also pay a fee-for-service claim on top of it. Whether that is correct depends entirely on your contract, and getting it wrong in either direction costs real money.
What CO-24 means
- CO stands for Contractual Obligation. The adjusted amount is a contract matter between you and the payer; you cannot balance-bill the patient for it.
- 24 means "charges are covered under a capitation agreement/contract." The payer has a fixed payment arrangement in place and considers the service already settled under that contract.
This is not a claim quality issue or a medical-necessity decision. CO-24 is purely about the contract structure. A provider in a capitation arrangement cannot also receive fee-for-service payment for the same service that the capitation covers. If you submit one, it comes back CO-24.
How capitation works
Under a capitation arrangement, the plan or IPA (independent practice association) pays a fixed per-member-per-month (PMPM) amount to a provider to cover a defined scope of services for every assigned member, regardless of how often those members seek care. Primary care physicians in HMO plans are the most common example, but some specialist groups and ancillary providers operate under sub-capitation agreements as well.
The PMPM payment covers the service in advance. Submitting a fee-for-service claim for a service already in the cap scope creates a double-payment situation the payer will not allow. CO-24 is how it rejects the claim.
Three scenarios that produce CO-24
Before deciding how to respond, identify which situation you are in.
- You are capitated and the service is in scope. The denial is correct. The service belongs in the capitation encounter data process, not a fee-for-service claim. Redirect it to the IPA or plan administrator.
- The service is carved out of your capitation contract. Many capitation contracts exclude certain service categories (specialist referrals, hospital care, specific diagnostic tests) that are still billed fee-for-service even when primary care is capitated. If the denied service sits in a carved-out category, CO-24 is a payer error and should be disputed with contract documentation.
- You have no capitation arrangement with this payer. This is a pure payer error: the plan's adjudication system misidentified your contract type. Dispute immediately with a copy of your current contract showing the fee-for-service arrangement.
How to respond
The starting point is always your contract, not the ERA.
- Step 1: Confirm your contract type. Pull your actual agreement with this payer or call provider relations. Know definitively whether you have a capitation contract and, if so, which members and service categories it covers.
- Step 2: Check whether the service is in scope or carved out. Your contract should define covered services and exclusions explicitly. "Carved-out" services are often listed by CPT range, service category, or place of service.
- Step 3 (if in scope): Redirect the encounter. Submit through the IPA or plan administrator's encounter data system. Some administrators require encounter reports in a specific format rather than standard 837 claims; verify the correct method with the administrator before submitting.
- Step 3 (if carved out or not capitated): Dispute. File a provider dispute through the payer's contract dispute channel, citing the specific contract term or exclusion that confirms the service should be paid fee-for-service. Attach the relevant contract pages.
CO-24 vs. CO-22
These codes are easy to confuse because both involve contract structure, but they address different questions. CO-22 is a coordination-of-benefits (COB) code: "this care may be covered by another payer per COB rules." It is about who among multiple payers should pay first. CO-24 has nothing to do with other plans. It is about the payment model for your own contract with the primary payer. Both require understanding the patient's coverage, but they need different fixes.
CO-24 vs. CO-45
CO-45 means the billed charge exceeded the allowed amount under the fee schedule. It is a pricing issue. CO-24 is a payment-model issue: the payer is not disputing the charge amount; it is saying the charge belongs under a different payment mechanism entirely.
Preventing CO-24 in your billing workflow
- Maintain a contract inventory. For each payer relationship, document whether the contract is fee-for-service, capitated, or a hybrid, and list any carved-out service categories. One reference document shared with billing staff eliminates most CO-24s before claims leave the practice.
- Configure your billing system to flag capitated payers. Mark capitated payers and the applicable member populations so charge entry routes capitated encounters to the encounter data process rather than the standard claim queue.
- Audit after any new network or IPA enrollment. When you join a new IPA or managed care network, run a look-back on claims submitted to that plan after the effective date. Claims submitted fee-for-service during a capitation period are at risk for CO-24 on audit.
- Review capitation scope annually. Contracts renegotiate. A service that was carved out last year may fall into the capitation scope under a renewed contract. Update your billing configuration whenever a contract changes.
The bottom line
CO-24 is not a signal to write off a claim. It is a signal to verify your payment model. Confirm the contract type, check the service scope, and then either redirect the encounter or dispute the denial. Systematic CO-24 denials on carved-out services are a revenue leakage problem: the same configuration error silently writes off claim after claim until someone traces it to the contract. See the denial management guide for the broader workflow context.