In medical billing, denial management is an important part of the revenue cycle management (RCM) process. Sometimes billing teams may encounter is CO 256 denial code.
CO-256 denial code indicates that the payer has determined that the billed service is not payable under the provider’s managed care contract. The payer is saying that the service does not meet the payment terms or requirements of the specific managed care agreement.
What Is CO-256 Denial Code?
As per Claim Adjustment Reason Code (CARC) CO256 denial code means, “Service not payable per managed care contract.”
The main reason when claim denied due to below mentioned reasons
- Provider is out of network
- Services are not covered under plan contract
- Need Referral
- Prior authorization required
- Claim submission procedures
- Capitation Applied
- Services handled by another organization
When a claim does not meet one of these requirements, the payer may denied the claim with CO-256.
What Does CO-256 Mean in Medical Billing?
The insurance company reviewed the claim and determined that the service cannot be reimbursed under the applicable managed care agreement.
For example, a physician may provide a service that is clinically appropriate for the patient. However, if the physician is not participating in the patient’s specific managed care network, or the service is covered under a different payment arrangement, the payer may not reimburse the claim.
Common Causes of CO-256 Denial
There are several reasons why a payer may issue CO-256.
1. Provider Is Out of Network
One of the common reasons is that the provider is not contracted with the patient’s particular managed care plan. It is important to remember that being contracted with an insurance company does not always mean that the provider participates in every plan offered by that company.
2. Missing Referral
Some managed care plans require a referral from the patient’s primary care physician before the patient can see a specialist. If the required referral was not obtained, the claim may be denied.
3. Missing Pre-Authorization
Certain procedures, diagnostic tests, treatments, and other services may require prior authorization. If the required authorization was not obtained before the service, the payer may refuse payment.
However, when authorization is the specific reason for the denial, the billing team should also review whether another CARC, such as CO-197, applies.
4. Contractual Service Exclusion
A service may be excluded from the provider’s managed care agreement.
For example, a particular service may be:
- Excluded from the contract
- Covered by another vendor
- Carved out of the managed care arrangement
- Included under a separate benefit
- Subject to a different reimbursement arrangement
In these situations, simply resubmitting the same claim may not resolve the denial.
5. Capitated Arrangement
Some healthcare organizations operate under capitated agreements.
Under a capitated arrangement, a provider or medical group may receive a predetermined payment for certain services or patients.
If the provider submits a separate fee-for-service claim for a service that is already included in the capitated arrangement, the payer may deny it with CO-256.
6. Incorrect Payer or Claim Routing
Managed care claims may need to be sent to a specific payer, IPA, medical group, or delegated entity.
If the claim is sent to the wrong organization, the claim may be denied.
The billing team should verify the patient’s insurance card, plan information, payer ID, medical group, and claim routing instructions.
7. Patient Was Not Enrolled in the Plan
CO-256 may also occur when the patient’s managed care enrollment was not active on the date of service.
The patient’s insurance may appear active at another point in time, but the coverage must be verified for the actual date on which the service was provided.
How to Resolve CO-256 Denial
The correct resolution depends on the reason for the denial. The following process can help an RCM team investigate CO-256.
Step 1: Review the EOB or ERA
Start by reviewing the payer’s Electronic Remittance Advice (ERA) or Explanation of Benefits (EOB).
Look for:
- CO-256
- Related remark codes
- RARC codes
- Payer comments
- Denial descriptions
- Adjustment amounts
The accompanying remark code can provide additional information about the payer’s decision.
Step 2: Verify the Patient’s Insurance
Check the patient’s eligibility for the date of service.
Verify:
- Member ID
- Plan name
- Effective date
- Termination date
- Product type
- Managed care organization
- Medical group or IPA
- Primary care physician information
Do not rely only on the insurance company’s name. The patient’s specific plan is important.
Step 3: Check Provider Network Status
Confirm whether the provider was participating in the patient’s specific insurance plan on the date of service.
For example, being contracted with a payer’s commercial plans does not necessarily mean the provider is contracted with every Medicare Advantage or Medicaid managed care plan offered by that payer.
Step 4: Check Referral Requirements
If the patient’s plan requires a referral, verify whether one was obtained.
Check:
- Referral number
- Referring provider
- Referral date
- Authorized service
- Number of visits
- Validity period
If the referral was required but missing, determine whether the payer allows retroactive referral submission.
Step 5: Verify Prior Authorization
Determine whether the service required authorization.
If authorization was obtained, make sure the authorization information was correctly linked to the claim.
If it was not obtained, check whether the payer permits retroactive authorization or an appeal.
Step 6: Review the Managed Care Contract
If network, referral, and authorization issues are not responsible, review the applicable contract terms.
Look for:
- Covered services
- Excluded services
- Carve-outs
- Capitated services
- Delegated arrangements
- Reimbursement limitations
This step may require assistance from the contracting or payer relations department.
Step 7: Check Claim Routing
Make sure the claim was submitted to the correct entity.
This is especially important when the payer works with:
- IPAs
- Medical groups
- Delegated entities
- Independent physician associations
- Managed care organizations
If the claim was sent to the wrong payer or entity, submit it to the correct destination according to the applicable claim filing rules.
Step 8: Correct and Resubmit When Appropriate
A corrected claim may resolve CO-256 when the denial resulted from a claim submission or routing error.
For example, the billing team may have used:
- Incorrect payer information
- Incorrect plan information
- Incorrect member information
- Incorrect medical group information
However, repeatedly submitting the same claim will generally not solve a genuine contractual exclusion.
Step 9: Appeal When the Denial Is Incorrect
If the provider believes the payer incorrectly applied the contract terms, an appeal may be appropriate.
The appeal package may include:
- Appeal letter
- EOB/ERA
- Patient eligibility information
- Authorization documentation
- Referral documentation
- Medical records, when relevant
- Provider participation evidence
- Contract information
- Supporting payer correspondence
The appeal should clearly explain why the claim should be reimbursed.
Example of CO-256 Denial
Consider the following example:
A patient is enrolled in a managed care HMO plan and visits a specialist.
The specialist’s office verifies that the patient has active insurance but does not verify whether the specialist participates in the patient’s specific HMO network.
The provider performs the service and submits a claim.
The payer processes the claim and determines that the provider is not participating in that specific managed care plan.
The payer returns the claim with:
CO-256 – Service not payable per managed care contract.
How the RCM Team Should Handle It
The billing team should:
- Review the ERA/EOB.
- Verify the patient’s exact insurance plan.
- Check the provider’s network participation.
- Confirm participation on the date of service.
- Review the managed care contract.
- Determine whether the claim was incorrectly routed.
- Check whether the denial can be appealed.
- Follow the payer’s instructions for correction, appeal, or adjustment.
The team should not simply rebill the claim without identifying the actual reason for the denial.
CO-256 vs. CO-197
CO-256 and CO-197 can sometimes appear similar because both may be associated with managed care requirements.
However, they are not the same.
CO-197 specifically relates to precertification or authorization not being obtained.
CO-256 is broader. It means the service is not payable according to the managed care contract and may involve:
- Network participation
- Contract exclusions
- Referral requirements
- Capitation
- Claim routing
- Authorization
- Other contractual requirements
Therefore, the RCM team should review the entire ERA/EOB rather than looking at the CARC alone.
CO-256 vs. CO-109
CO-109 means not covered by this payer, generally indicates that the claim is not covered by the payer or that the payer is not responsible for the claim.
CO-256 is more specifically related to the terms of a managed care contract.
When either denial occurs, the RCM team should verify eligibility, payer information, plan details, and claim routing.
How to Prevent CO-256 Denials
Preventing CO-256 is usually more effective than trying to recover the claim after the denial occurs.
Verify Eligibility Before the Claim Submission:
Eligibility verification should be performed before the patient’s visit. The verification process should include more than checking whether insurance is active.
The team should also verify:
- Specific plan
- Network status
- Referral requirements
- Authorization requirements
- Medical group
- Effective dates
- Benefit limitations
Verify Provider Participation
Confirm that the provider participates in the patient’s exact insurance product. Do not assume that participation with one product automatically means participation with another product from the same insurance company.
Authorization
Create a process for identifying services that require prior authorization. The scheduling or authorization team should complete this process before the service is performed whenever possible.
Referral Requirements
For plans requiring referrals, make referral verification part of the pre-service workflow.
The referral should be checked for the correct provider, service, dates, and number of authorized visits.
Payer Information Updated
Insurance companies frequently have different plans and claim-routing requirements.
Maintain updated information for:
- Payer IDs
- Medical groups
- IPAs
- Delegated entities
- Claim addresses
- Authorization contacts
- Plan-specific rules
CO-256 Denial Management Workflow
An effective RCM workflow can be summarized as:
Denial Received → Review ERA/EOB → Identify Contract Issue → Verify Eligibility → Check Network Status → Verify Referral/Authorization → Review Contract → Correct/Reroute/Appeal → Post Appropriate Adjustment
This workflow helps the billing team avoid unnecessary claim resubmissions and focus on the actual reason for the denial.
Important RCM Tip
One of the biggest mistakes in denial management is treating every CO-256 as a simple billing error.
CO-256 is often connected to the relationship between the provider, patient plan, managed care organization, and contractual payment arrangement.
Therefore, the denial should be investigated from both the billing and contracting perspective.
A successful denial-management process should identify the root cause and then correct the workflow that allowed the denial to happen.
Related Articles:
Denial Code CO197- Pre-Auth Not Found
5 thoughts on “CO 256 Denial Code Description (2026)”