CO-24 Denial Code: Causes, Solutions & How to Prevent It [2026]

Nearly 20% of all medical claims get denied on the first submission. That's roughly one out of every five claims your team processes. And capitation-related denials like CO-24? They're among the most misunderstood codes in medical billing.

Denial codes are messages from payers explaining why a claim wasn't paid. They're not just administrative noise. Each one points to a specific problem, and fixing that problem is how you recover revenue. Ignoring it is how you lose it.

CO-24 shows up frequently in practices that treat Medicare Advantage patients, Medicaid managed care enrollees, and HMO members. The frustrating part? Many billing teams either misread this code, confuse it with other denials, or simply write it off without investigating whether the denial was even correct.

That's a costly mistake. And it's entirely fixable with the right approach to effective denial management.

In this guide, we break down exactly what the CO-24 denial code means, why it occurs, how to resolve it step by step, and how to prevent it from recurring. No fluff, no jargon walls. Just the practical information your billing team needs to stop leaving money on the table.

What Is the CO-24 Denial Code?

CO-24 Denial Code Definition

The CO-24 denial code is a Claim Adjustment Reason Code (CARC) that indicates a claim was denied because the billed service is covered under a capitation agreement or managed care plan.

In practical terms, this means the payer has already compensated the provider through a fixed, pre-negotiated payment, typically calculated on a per member per month (PMPM) basis. The service can't be billed separately on top of that.

Here's what CO-24 is not: it's not a medical necessity denial. It's not a timely filing issue. And it's not about your fee schedule being too high. It is specifically about capitation and managed care coverage.

Official CARC Description for Code 24:
"Charges are covered under a capitation agreement/managed care plan."
Source: Washington Publishing Company (WPC) / ASC X12

That one-liner on your EOB carries real financial implications. Understanding what sits behind it is the first step toward handling it correctly.

What Does "CO" (Contractual Obligation) Mean?

The "CO" in CO-24 stands for Contractual Obligation. That designation changes everything about how you handle the denial.

When a denial carries the CO group code, the provider is contractually responsible for the denied amount. You can't bill the patient for it. You can't send it to collections. It's a write-off under your payer contract.

Compare that with two other group codes you'll see on the remittance advice:

• PR (Patient Responsibility): The patient owes the denied amount.

• OA (Other Adjustment): A payer-initiated adjustment that's neither the provider's nor the patient's responsibility.

Bottom line: if you see CO-24, the denied amount is your contractual write-off. The patient doesn't owe a dime for that charge.

CO-24 vs. PR-24: Who Is Responsible for Payment?

This distinction trips up billing staff more often than you'd expect. Here's the clearest way to think about it:

Billing a patient for a CO-24 amount isn't just a mistake. It's a compliance violation under most payer contracts, and in some states, it violates balance-billing laws. Getting this wrong creates legal exposure on top of financial confusion.

CO-24 Denial Code Description: What It Actually Means

The CO-24 denial code description, per the official CARC code set, states: "Charges are covered under a capitation agreement/managed care plan." In plain language, the payer has already paid the provider a fixed monthly amount to cover the billed service. No additional payment will be made.

So what exactly is a capitation agreement? It's a contract between a healthcare provider and a managed care organization (MCO) or insurance payer. Under this arrangement, the MCO pays the provider a fixed fee, typically per member per month (PMPM), regardless of how many services the patient receives during that period.

Since the provider has already been compensated through that fixed payment, submitting a separate fee-for-service claim triggers the CO-24 denial. The payer's system sees the charge, checks the patient's enrollment, confirms the capitation contract covers it, and denies the claim.

This denial code applies across a wide range of services: inpatient hospital stays, outpatient visits, lab tests, diagnostic imaging, and specialist consultations. If the service falls within the scope of the capitation contract, it's subject to CO-24.

One more thing worth clearing up: several competing resources online define CO-24 as a "medical necessity" denial or a "fee schedule overcharge." That's incorrect. CO-24 has nothing to do with medical necessity or fee schedules. It is exclusively about the capitation payment model. Getting the definition wrong leads to the wrong resolution strategy, which leads to wasted time and lost revenue.

Common Reasons for the CO-24 Denial Code

The CO-24 denial code can stem from several billing, eligibility, and contractual issues. Understanding these root causes is how you stop the same denials from showing up month after month.

Here's a quick-reference summary before we dig into each one:

Service Covered Under a Capitation Agreement

This is the most straightforward trigger. The patient is enrolled in a capitated plan. Your practice receives a fixed monthly payment for their care. When your billing team submits a separate claim for a service that's already included in that capitation payment, the payer denies it.

The logic is simple from the payer's perspective: they've already paid you for this. The claim is essentially asking them to pay twice.

Claim Submitted to the Wrong Payer

This one comes up constantly with Medicare patients. A patient has Medicare Advantage (Part C), but the claim gets submitted to Original Medicare (Part A/B). Original Medicare looks at the claim, sees the patient is enrolled in a managed care plan, and kicks it back with CO-24.

The fix is routing the claim to the correct MCO. But the damage is already done: your team spent time on a claim that was never going to pay from that payer.

Missing Prior Authorization or Referral

Some capitation and managed care plans require prior authorization before certain services are rendered. Skip that step, and the claim gets denied. Not because the service was unnecessary, but because the plan's administrative requirements weren't met.

What makes this frustrating is that the service might have been completely appropriate. The denial isn't clinical. It's procedural.

Out-of-Network Provider

If your practice isn't contracted with the patient's managed care plan, the MCO may deny the claim under CO-24. Many managed care plans restrict coverage to in-network providers only.

This is why provider enrollment and credentialing matters so much on the front end. If you're not in-network before you deliver care, you're setting yourself up for denials that are nearly impossible to overturn.

Outdated Coordination of Benefits (COB) Information

Patients with multiple insurance plans create routing complexity. When a patient has Medicare plus a supplemental plan, or Medicaid plus a managed care plan, and the COB information hasn't been updated, claims end up at the wrong payer. That wrong payer sends back a CO-24.

The root cause here is usually a registration issue. The front desk either didn't ask about other coverage or didn't update the system with the correct payer hierarchy.

AI-Driven Automated Denials (Emerging Trend)

This one is newer, and it's growing fast. Payers are increasingly deploying artificial intelligence and machine learning algorithms to adjudicate claims automatically. These systems scan for capitation-related billing patterns and deny claims in bulk.

The problem? Automated systems aren't always right. They flag services that might actually be carved out of the capitation agreement. They deny claims based on enrollment data that's out of date on the payer's end. And they do it at scale, which means your practice could see a sudden spike in CO-24 denials that aren't all legitimate.

This makes proactive denial management and human review of denied claims more critical than ever. Blindly accepting AI-generated denials means leaving valid revenue on the table.

Managing CO-24 denials takes time your team may not have. MedSole RCM's denial management services identify denial root causes, handle appeals, and implement prevention protocols, so you can focus on patient care.

CO-24 Denial Code in Medicare vs. Medicaid

CO-24 denials play out differently depending on the payer. Medicare and Medicaid each have their own managed care structures, and the billing mistakes that trigger this code vary between them. Knowing these differences helps your team route claims correctly the first time.

CO-24 Medicare Denial: Medicare Advantage Billing Errors

The most common CO-24 Medicare denial happens when a provider bills Original Medicare (Parts A/B) for a patient who's actually enrolled in a Medicare Advantage plan (Part C).

Here's how that works. Medicare Advantage plans are run by private insurers like UnitedHealthcare, Humana, and Aetna. When a patient enrolls in one of these plans, it replaces Original Medicare for nearly all services. The MCO handles claims, not CMS.

One exception: hospice care. Original Medicare still covers hospice services even when the patient has Medicare Advantage. Everything else goes through the Part C plan.

If your team submits a claim to Original Medicare for a Medicare Advantage patient, you'll get a CO-24 denial. Original Medicare sees the managed care enrollment and kicks the claim back.

The fix is straightforward. Verify enrollment through CMS's provider enrollment tools or check the patient's insurance card for their MCO information. Then submit the claim to the correct Medicare Advantage plan. Don't assume every Medicare patient is on Original Medicare; that assumption is where most of these denials start.

CO-24 Medicaid Denial: State-Specific Managed Care Considerations

Medicaid CO-24 denials follow a similar pattern but with an extra layer of complexity: state-by-state variation.

Most states have moved a large portion of their Medicaid population into managed care plans run by Medicaid MCOs. If your practice bills the state's fee-for-service Medicaid program for a patient who's enrolled in a Medicaid MCO, that claim will come back as CO-24.

What makes Medicaid tricky is the carve-out situation. Some states carve specific services out of managed care and continue covering them under fee-for-service Medicaid. Behavioral health is a common example. Dental is another. These carved-out services should be billed to the state Medicaid program, not the MCO.

Your billing team needs to know your state's Medicaid managed care structure. There's no universal rule here. What's capitated in Texas might be carved out in New York.

Always verify the patient's Medicaid managed care enrollment through your state's Medicaid portal or eligibility verification system before submitting claims. A 30-second check on the front end saves days of rework on the back end.

Navigating payer-specific denial rules across Medicare, Medicaid, and commercial plans is complex. MedSole RCM's denial management specialists resolve capitation-related denials daily, and provider credentialing at $99 per insurance ensures your practice is enrolled with the right MCOs from the start.

How to Resolve the CO-24 Denial Code: Step-by-Step

When a CO-24 denial hits your inbox, a systematic approach keeps you from wasting time on the wrong fix. Not every CO-24 requires an appeal. Some need a corrected claim. Others just need a clean write-off. These five steps help you figure out which path to take.

Step 1: Review the ERA/EOB and Identify the CARC/RARC

Start with the Electronic Remittance Advice (ERA) or Explanation of Benefits (EOB). Look for the CARC code (CO-24) and any Remittance Advice Remark Codes (RARCs) that came with it. The RARC often tells you more than the CARC alone.

For example, an accompanying remark code might clarify whether the denial stems from capitation, incorrect payer routing, or a COB issue. That distinction changes your next move entirely. Don't skip this step; it takes two minutes and saves hours of guessing.

Step 2: Verify Patient Eligibility and Capitation Status

Confirm the patient's insurance enrollment as of the date of service. Was the patient actually in a capitated plan or managed care arrangement when you provided care? Use the payer's eligibility verification portal, call the MCO, or check through your practice management system.

Sometimes the answer surprises you. Patients switch plans mid-month. Retroactive enrollment changes happen. What looked like a valid fee-for-service patient at check-in may have already been capitated by the time the claim was processed.

Your comprehensive medical billing services partner should be catching these discrepancies before claims go out the door.

Step 3: Check Capitation Contract Terms (Carved-Out vs. Bundled Services)

Pull your capitation contract with the relevant MCO. Look for the service list. Is the denied service bundled into the capitation payment, or is it carved out?

This is where a lot of revenue gets left behind. Many capitation contracts carve out specific services: lab work, specialty referrals, durable medical equipment, certain procedures. If the denied service is on the carved-out list, the CO-24 denial may be wrong.

Keep a reference sheet for each payer listing what's capitated and what's not. When your team can look this up in 30 seconds instead of digging through a 40-page contract, resolution happens faster.

Step 4: Resubmit to the Correct Payer or Write Off the Amount

Two possible outcomes here, and they require opposite actions.

If the claim went to the wrong payer (Original Medicare instead of Medicare Advantage, for instance), resubmit it to the correct managed care plan with the right payer ID and member information.

If the service is legitimately included in the capitation payment, write off the denied amount as a contractual adjustment. The patient can't be billed for it. CO-24 carries the "CO" group code, which means this is your contractual obligation to absorb.

Getting this decision right matters for accurate CO-24 denial code reimbursement tracking and clean A/R.

Step 5: File an Appeal if the Denial Is Incorrect

When you've confirmed the service is carved out of capitation, or the patient wasn't enrolled in the managed care plan at the time of service, file a formal appeal.

Most payers allow 180 days from the denial date. Medicare Advantage plans follow CMS appeal timelines. Medicaid MCOs can be shorter, sometimes 60 to 90 days depending on the state.

Include these with your appeal: the capitation contract section showing the service is carved out, eligibility verification records from the date of service, prior authorization documentation if it applies, and a cover letter explaining specifically why the denial is incorrect.

Don't send a generic appeal letter. Payers process thousands of appeals. The ones with clear documentation and a specific argument get resolved. The vague ones sit in a pile.

Your AR follow-up and appeals process should track appeal deadlines automatically so nothing slips past the filing window.

Resolving CO-24 denials requires expertise in capitation contracts, payer policies, and appeal timelines. MedSole RCM's dedicated denial management team resolves capitation-related denials with a recovery rate that consistently outperforms industry benchmarks. Get a free denial analysis →

How to Prevent CO-24 Denials: 5 Proactive Steps

Fixing denials after they happen costs your practice time and money. Preventing them costs almost nothing. These five steps, built into your daily workflow, can cut CO-24 denial rates significantly.

Step 1: Verify Eligibility and Capitation Status Before Every Visit

Before any patient encounter, check whether their coverage falls under a capitation agreement. Real-time eligibility verification tools make this a 30-second task. Look at the patient's insurance card for MCO information, or query the payer's portal directly.

Flag capitated patients in your practice management system. When billing staff can see that flag before they submit a claim, they know not to send a separate fee-for-service charge for bundled services. That one flag prevents the most common CO-24 trigger.

Step 2: Understand Your Capitation Contract Inside and Out

Keep copies of every capitation contract your practice has signed. Build an internal reference sheet for each payer that lists which services are bundled into the capitation and which are carved out for separate billing.

Contracts change. Payers renegotiate terms. Services that were carved out last year might be bundled this year. Review your contracts whenever they're renewed, and update your reference sheets accordingly.

Step 3: Verify the Payer Hierarchy (Coordination of Benefits)

Patients with multiple insurance plans create routing complexity. Always check the Coordination of Benefits (COB) to determine which payer is primary, secondary, and so on.

Submitting to the wrong payer in the hierarchy is one of the top CO-24 triggers. Collect COB information at registration and verify it at every visit. Patients don't always volunteer that they've picked up new coverage.

Step 4: Train Billing and Front-Desk Staff Regularly

Your team can't prevent what they don't understand. Make sure billing staff, front desk employees, and clinical team members all grasp the basics: what capitation means, how to spot a capitated patient, which services can't be billed separately, and how to verify payer information.

Quarterly refresher sessions work well. So does a quick training update whenever a new payer contract comes in. The investment in training pays for itself many times over in avoided rework.

Step 5: Use Technology to Flag Capitated Claims Before Submission

Modern billing software can catch CO-24 triggers before claims ever leave your office. Set up claim scrubbing rules that check for capitation status. Configure automated alerts for patients enrolled in managed care plans.

These edits take minutes to set up in most systems. They catch mistakes that manual review misses, especially during high-volume billing days when your team is moving fast.

Integrating these prevention steps into your practice's revenue cycle management solutions turns denial prevention from a reactive scramble into a built-in safeguard.

Can You Appeal a CO-24 Denial?

Yes, you can appeal a CO-24 denial, but not every one deserves an appeal.

Appeal when the denied service is carved out of the capitation agreement, when the patient wasn't enrolled in the managed care plan at the time of service, or when a payer system error caused an incorrect denial. In these situations, you have a legitimate case, and the appeal is worth pursuing.

Don't appeal when the service is genuinely included in the capitation payment. The denial is valid. The correct action is a contractual write-off. Filing an appeal you can't win wastes your team's time and clutters the payer's queue.

Timelines matter. Most payers allow 180 days from the denial date to file. Medicare Advantage plans follow CMS appeal timelines. Medicaid MCOs often have shorter windows, sometimes as few as 60 to 90 days depending on the state. Miss the deadline, and it doesn't matter how strong your case is.

When you do appeal, include specific documentation:

• The section of your capitation contract showing the service is carved out

• Patient eligibility verification records from the date of service

• Prior authorization documentation, if the plan required it

• A cover letter that explains, specifically, why the denial is incorrect

Generic appeal letters get generic results. The more precise your documentation, the faster the resolution. Payer appeals teams respond to evidence, not persuasion.

Financial Impact of CO-24 Denials on Your Practice

Unresolved CO-24 denials don't just create paperwork. They drain revenue, tie up staff, and slow down your entire billing operation. And the real cost goes beyond the denied amount itself.

Every denied claim requires someone on your team to stop what they're doing, pull the claim, research the issue, contact the payer, and either resubmit or write it off. That's time your staff could spend working clean claims or following up on aging accounts.

Here's what the numbers look like:

Figures represent industry averages compiled from MGMA, AAPC, and HFMA data. Actual impact varies by specialty, payer mix, and practice size.

Think about what that means at scale. A practice processing 500 claims per month with even a 5% CO-24 denial rate is looking at 25 denied claims. At $25 to $118 in rework costs per claim, that's $625 to $2,950 in administrative costs alone, before you even count the delayed or lost revenue from the denied services.

For practices with a heavy managed care patient mix, these denials accumulate fast. Investing in accurate billing processes and proactive denial management delivers measurable ROI, often within the first billing cycle.

MedSole RCM helps healthcare providers recover revenue lost to denials like CO-24, with full-service medical billing starting at just 2.99% of collections and provider credentialing at $99 per insurance. Our denial management specialists maintain one of the highest denial recovery rates in the industry. See how we can help →

CO-24 vs. Related Denial Codes: Key Differences

CO-24 gets confused with other contractual obligation codes more often than it should. Several competitors in the billing education space have even published guides defining CO-24 as a fee schedule issue or a timely filing problem. That's incorrect, and acting on the wrong definition leads to the wrong resolution.

Here's how CO-24 actually compares to the denial codes it's most commonly mixed up with:

The distinction matters because each code requires a different resolution approach. Treating a CO-24 like a CO-45 means adjusting your fee schedule when the real issue is capitation enrollment. That doesn't fix anything.

If you're seeing multiple denial codes across your claims, a systematic denial management review can uncover patterns and address root causes across all code categories.

Real-World Example: How a CO-24 Denial Happens and Gets Resolved

Concepts make more sense with a real scenario. Here's one that plays out in practices every week.

The setup: Dr. Smith's family practice provides primary care to patients enrolled in a regional HMO. Under the practice's capitation contract, the HMO pays $45 PMPM for each enrolled patient. That payment covers routine office visits, preventive screenings, and basic lab work.

What went wrong: A medical assistant schedules a routine wellness visit for a capitated patient. After the visit, the billing team submits a fee-for-service claim for the office visit (CPT 99213) to the HMO. The HMO denies the claim with CO-24, stating the charges are covered under the capitation agreement.

How it got fixed: The billing manager pulls the capitation contract, confirms that routine office visits fall under the PMPM payment, and writes off the denied amount as a contractual adjustment. No appeal needed. The denial was valid.

The prevention step: The billing manager flags the patient's record in the practice management system as capitated. Going forward, billing staff can see the flag before submitting claims and won't send separate charges for bundled services.

That's the whole cycle: identify, verify, resolve, and prevent. It took the billing manager about 20 minutes. Without the flag in place, the same mistake would have repeated with every capitated patient visit.

Frequently Asked Questions About CO-24 Denial Code

What does CO-24 denial code mean?

The CO-24 denial code means the billed service was denied because it's covered under a capitation agreement or managed care plan. The provider has already received a fixed payment for the patient's care, so separate fee-for-service billing for included services isn't permitted. The "CO" group code indicates this is a contractual obligation; the patient can't be billed for the denied amount.

What does "charges are covered under a capitation agreement/managed care plan" mean?

That phrase is the official CARC description for code CO-24. It means the payer has a contract with the provider to pay a set amount per member per month for the patient's care. The billed service falls within that prepaid arrangement, so it can't be charged separately on top of the capitation payment.

Is CO-24 a patient responsibility?

No. CO-24 carries the "CO" (Contractual Obligation) group code, which means the denied amount is the provider's responsibility to write off. The patient can't be billed for charges denied under CO-24. Balance-billing a patient for a CO amount violates most payer contracts and, in some states, violates consumer protection laws.

How do I resolve a CO-24 denial code?

Review the ERA/EOB to confirm the denial reason. Verify the patient's capitation enrollment status at the time of service. Check your capitation contract to determine if the service is bundled or carved out. If the claim went to the wrong payer, resubmit to the correct MCO. If the service is legitimately capitated, write off the amount. If the denial is incorrect, file an appeal within 180 days with supporting documentation.

Can you appeal a CO-24 denial?

Yes, if the service was incorrectly flagged as capitated. Common appeal-worthy scenarios include services that are carved out of the capitation contract, patients who weren't enrolled in the managed care plan at the date of service, and payer system errors. Most payers allow 180 days to file. Include the relevant contract section, eligibility records, and a cover letter explaining the error.

What is a CO-24 denial for Medicare?

A CO-24 Medicare denial typically occurs when a claim is submitted to Original Medicare for a patient enrolled in a Medicare Advantage plan (Part C). Medicare Advantage replaces Original Medicare for most services, so claims must go to the private insurer managing the patient's Part C coverage. The one exception is hospice care, which Original Medicare still covers for Medicare Advantage patients.

What is the difference between CO-24 and CO-45?

CO-24 indicates a service is covered under a capitation agreement; the issue is the payment model. CO-45 indicates charges exceed the provider's contracted fee schedule; the issue is the billed rate. They require completely different resolutions. CO-24 calls for verifying capitation status and potentially resubmitting or writing off. CO-45 calls for adjusting the billed amount to match the contracted rate.

What are the most common mistakes that cause CO-24 denials?

Three mistakes account for most CO-24 denials: failing to verify whether the patient is enrolled in a capitated or managed care plan before delivering care, submitting claims to the wrong payer (Original Medicare instead of Medicare Advantage being the most frequent example), and billing separately for services that are already included in the capitation agreement.

Stop Losing Revenue to CO-24 Denials

CO-24 denials are among the most preventable denial types in medical billing. Verify eligibility before every visit. Know your capitation contracts. Train your billing team on managed care workflows. Set up system flags that catch capitated claims before they go out the door.

When denials do show up, a clear resolution process keeps them from turning into lost revenue. Review the ERA, check the contract, resubmit or write off appropriately, and appeal when the denial is wrong.

But here's the reality: managing denials internally takes time, specialized knowledge, and consistent follow-through that many practices struggle to maintain.

If this sounds familiar, MedSole RCM can help.

MedSole RCM is a full-service revenue cycle management company that specializes in denial management, claims resolution, and revenue recovery for healthcare providers across all specialties. Our team identifies denial patterns, including capitation-related denials like CO-24, and implements root-cause fixes that prevent them from recurring.

What makes MedSole RCM different:

• Medical billing services starting at 2.99% of collections, among the most competitive rates in the industry

• Provider credentialing at $99 per insurance, fast, accurate, and fully managed

• Dedicated denial management with one of the highest recovery rates in the market

• End-to-end revenue cycle management from patient eligibility through final payment posting

Want to see what your practice is losing to preventable denials? Request a free denial analysis →