CO 24 Denial Code: What It Means and How to Fix It
You open an ERA, see CO 24 on a claim, and the payment is $0. The CO 24 denial code tells you the payer believes the charges are already covered under a capitation agreement or a managed care plan. Sometimes that is correct and nothing is wrong. Other times the claim went to the wrong payer, or the patient’s plan information is out of date.
This guide explains what CO 24 means, how to tell a valid denial from a billing error, and the steps to fix it.
What does the CO 24 denial code mean?
CO 24 means “Charges are covered under a capitation agreement or managed care plan.” The payer is saying it already pays for these services through a fixed, prepaid arrangement, so it will not pay a separate fee for this claim.
The “CO” is a group code and stands for Contractual Obligation. The “24” is a claim adjustment reason code. Together they tell you the amount was not paid because of a contract term, and the practice cannot bill the patient for it.
That last point matters. When a payer uses CO, the balance is the provider’s write-off, not the patient’s bill. Sending a statement to the patient for a CO 24 amount is a common mistake and can cause complaints and compliance problems.
Why capitation causes this denial
Capitation is a payment model where a health plan pays a provider or provider group a fixed amount per member, per month. The amount does not change with the number of visits. The provider takes on the job of covering the member’s care within the agreed scope.
Here is a simple, fictional example. A health plan pays a primary care group $30 per member per month for 1,000 members. That is $30,000 a month, whether those members visit once or ten times. If a patient from that panel sees a doctor in the group and the practice also sends a fee-for-service claim to the plan, the plan can reject it with CO 24. It has already paid for that care through the monthly payment.
Capitation is common in Medicaid managed care, Medicare Advantage, and some HMO and commercial arrangements. The exact services included depend on the contract, so two plans from the same payer can behave differently.
CO versus PR: who pays the balance
Group codes decide who is responsible for the unpaid amount. You will see these four most often.
| Group code | Meaning | Who owes the balance |
|---|---|---|
| CO | Contractual Obligation | The provider (write-off) |
| PR | Patient Responsibility | The patient |
| OA | Other Adjustment | Depends on the reason |
| PI | Payer Initiated Reduction | Depends on the payer’s reason |
CO 24 should come with the CO group code. If you ever see 24 under PR, do not bill the patient until you confirm with the payer. The coding does not match the meaning of the reason code, and it may be a payer error.
Where you see CO 24 on the remittance
CO 24 appears in the CAS segment of the 835 electronic remittance advice (ERA), and on paper remittances in the adjustment or reason column. If you work with 835 medical billing files, you will find it on the claim line or the service line, depending on how the payer reports it.
The code may also come with a remittance advice remark code (RARC), which gives more detail. Do not stop at the CARC. Read the remark code too, because it often points to the next step.
The code list itself, called claim adjustment reason codes or CARC codes, is maintained by the X12 organization. The list is updated several times a year, so check the current version for wording changes. Your clearinghouse or practice management system may show shortened descriptions that leave out detail.
Common causes of a CO 24 denial
CO 24 is not always a mistake. Sort the causes into three groups so you know whether to fix, redirect, or write off.
The denial is valid
The patient is enrolled in a capitated plan, and the service is covered under the capitation payment. This commonly happens when:
- The patient is assigned to your medical group under a capitation contract, and the service is included within that agreement.
- The claim is submitted as an encounter claim. Capitated providers often submit claims only to report the visit, resulting in a $0 payment with CO 24 as the expected outcome.
In these situations, no correction is required. Post the adjustment and move forward.
The claim went to the wrong payer or entity
This is the most common correctable reason for CO 24. Some health plans delegate payment responsibility to a medical group, independent practice association (IPA), or specialty vendor. The payer name may appear on the insurance card, but the capitated entity is responsible for payment.
Examples:
- The patient’s insurance card lists a managed care plan, but your agreement is with the IPA that receives the capitation payment.
- Laboratory, radiology, or behavioral health services may be carved out and assigned to a separate vendor that operates under a capitated arrangement.
The patient’s coverage data is out of date
The patient may have changed from fee-for-service coverage to a managed care plan. If your system still contains outdated insurance information, the claim may be submitted to the wrong payer. Eligibility changes during open enrollment or at the beginning of a plan year are common reasons this occurs.
A fourth, less common reason is a payer processing error. If the service is outside the capitation scope but CO 24 is applied incorrectly, the claim may require an appeal.
How to fix a CO 24 denial, step by step
- Read the full remittance. Note the CARC, the RARC, the group code, the payer name, and the claim and service line affected.
- Verify eligibility again. Run a real-time eligibility check for the date of service. Look at the plan type, the primary care provider (PCP) assignment, and any capitation or delegated entity listed.
- Check your contract. Find out whether your group is paid on capitation for this payer, and which services the capitation covers. Many contracts list carve-outs, which are services paid fee-for-service on top of the monthly payment.
- Decide the category. Is it valid, misdirected, or a payer error? The next steps depend on this.
- If valid: Post the CO adjustment as a contractual write-off. Do not bill the patient. Note the account so staff understand why the balance is zero.
- If misdirected: Correct the payer or the billing entity, and submit a new claim to the right place. Watch the filing deadline. It runs from the date of service, not from the date of the denial, and it varies by payer.
- If the service is a carve-out or a payer error: File a corrected claim or an appeal. Include the contract section that lists the service as outside capitation, the eligibility response, and the original remittance.
- Record the cause. Add the denial reason to your tracking log so you can see patterns by payer and by location.
A short phone call to the payer provider line often settles questions about capitation scope faster than a written appeal. Write down the call date, the representative’s name, and the reference number.
A worked example (fictional)
A three-doctor family practice, which we will call Riverside Family Care, gets 40 claims back with CO 24 from the same Medicaid managed care plan in one week.
The billing manager pulls the remittances and finds that 31 of the 40 belong to patients assigned to a different primary care group. Those patients were seen for urgent visits. The plan had delegated payment for those members to an IPA, and the practice billed the plan directly.
The other nine claims belong to patients assigned to Riverside’s own panel. Those are valid CO 24 denials because Riverside already receives capitation for them. The team posts those as write-offs and sends the 31 claims to the IPA.
The lesson: one denial code can hide two very different problems. Sorting by cause saved the practice from writing off money it could still collect. (This example is illustrative only. It is not drawn from real patient data.)
How to prevent CO 24 denials
You cannot prevent the valid ones, but you can reduce the avoidable ones.
Verify eligibility at every visit, not just the first. Plan type and PCP assignment can change monthly for managed care members. A check on the day of service catches most changes.
Record the full payer chain. Store the health plan, the delegated entity or IPA, and the member ID for each one. Many front desks only capture the name on the card.
Flag capitated patients in your system. Add a visible alert on the account. Staff then know whether to submit a fee-for-service claim or an encounter claim.
Keep a contract summary. A one-page list of which services are capitated and which are carved out saves time. Update it each time a contract renews.
Train front desk and billing staff. They should know the difference between a valid CO 24 and a fixable one.
Track denials by code and payer. If CO 24 jumps from a few claims a month to dozens, something changed upstream, such as a new payer arrangement.
CO 24 compared with codes people confuse it with
Billers often mix up CO 24 with other adjustment reason codes. These are the ones that look similar in practice.
| Code | Short meaning (check current CARC wording) | How it differs from CO 24 |
|---|---|---|
| CO 22 | Care may be covered by another payer per coordination of benefits | Points to a different insurer, not a capitation arrangement |
| CO 97 | Benefit is included in the payment for another service | Bundled into another service’s payment, not prepaid |
| CO 109 | Claim not covered by this payer; send to the correct payer | Wrong payer, with no capitation implied |
| CO 18 | Duplicate claim or service | The payer already received this claim |
CO 24 and CO 109 are the closest pair. Both can mean “this claim belongs somewhere else.” The difference is that CO 24 specifically points to a capitation or managed care payment arrangement.
Using CARC codes in your denial workflow
Reading one remittance is manageable. Reading thousands is where a system helps. Many practices lose track of CO 24 because it sits in a long list of medical denial codes and adjustment codes that nobody sorts.
A simple workflow:
- Auto-post known adjustments. Set your system to post valid CO 24 write-offs on capitated accounts without manual work.
- Create a work queue for the rest. Route CO 24 on non-capitated or unassigned patients to a person who can check eligibility and payer.
- Report monthly. Count CO 24 denials by payer, by provider, and by cause. A small table is enough.
- Review the CARC list. Compare the code list with your system’s descriptions at least once a year.
If you want an outside view, a billing partner can audit your last 90 days of remittances, group denials by reason code, and show which ones are avoidable. If CO 24 and other denials are eating into your revenue, our team can review your recent claims and tell you where the money is leaking.
