What does denial code CO-256 mean?

CO-256 means the service is not payable to this provider under the managed care contract that governs the patient. The care may be covered and appropriate, yet still fall outside the specific agreement, a carve-out, or an existing capitated payment.

Can I bill the patient after a CO-256 denial?

No. A service that falls outside your contract's scope is a contracting problem between you and the plan, not a patient balance. Identify the delegated entity that does pay for it and rebill there, or take the gap to contract negotiation.

CO-256: The service is not payable under the managed care contract

CO-256 points at the contract rather than the claim. The service may be a covered benefit and clinically appropriate, and still not be payable to you under the specific managed care agreement in force. That usually means the service belongs to a delegated entity, sits outside your contracted service categories, or falls under a capitated payment already made. Because the cause is contractual, the resolution runs through contracting rather than through resubmission.

What it means: The managed care agreement governing this patient does not make this service payable to this provider.
Who pays the balance: Contractual - a service outside the contract's scope is not converted into a patient balance.
Group code CO: Contractual Obligation - the provider absorbs the balance and cannot bill the patient

Why CO-256 happens

The service is delegated to another entity under the managed care arrangement, such as a carved-out behavioural health or imaging vendor.
The provider's contract covers some service categories with this plan but not the one billed.
The service is included in a capitated payment the group already receives for the member.
The claim was submitted to the health plan when the delegated group is the correct payer.
The contract covers the plan's commercial products but not the managed Medicaid or Medicare product the member holds.

How to fix a CO-256 denial

1
Determine which entity actually pays for this service
Carve-outs are common in managed care, and the delegated vendor is frequently a different company entirely with its own claims address and filing rules.
2
Compare the service against your contracted categories
Read the contract's covered services schedule rather than assuming a general agreement covers everything. Gaps here are contracting issues, not billing errors.
3
Rebill the delegated entity within its own filing window
The delegated payer's timely filing clock generally runs from the date of service, so time spent on the wrong payer counts against it.
4
Escalate to contracting where the scope is genuinely wrong
If the service should be in the contract and is not, that is an amendment discussion. Continuing to bill into a gap generates the same denial indefinitely.

Deadlines depend on the payer

Filing limits and appeal windows for CO-256 vary by payer and often by plan type within the same payer. Look up the specific payer to see its verified deadlines and the source document they came from.

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Preventing CO-256 denials

Map each managed care contract's covered service categories and carve-outs before billing into a new plan.
Identify the delegated vendors for each managed care product in your market so claims route correctly the first time.
Confirm which product lines a contract covers, since commercial and government products are frequently separate agreements.

CO-256 frequently asked questions

What does denial code CO-256 mean?: CO-256 means the service is not payable to this provider under the managed care contract that governs the patient. The care may be covered and appropriate, yet still fall outside the specific agreement, a carve-out, or an existing capitated payment.
Can I bill the patient after a CO-256 denial?: No. A service that falls outside your contract's scope is a contracting problem between you and the plan, not a patient balance. Identify the delegated entity that does pay for it and rebill there, or take the gap to contract negotiation.

Related denial codes

CO-24 CO-147 CO-109 CO-243

Last reviewed August 5, 2026.

Denial code explanations are original plain-English summaries written for reference and are not the official X12 code descriptions. Payer handling of any code varies by contract - always verify against the remittance advice and your payer agreement before adjusting a claim.