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CO-300 Denial Code: Forwarded to Behavioral Health Plan

CO-300 means the patient's medical plan has no benefit for these services because behavioral health is handled by a separate plan or vendor, and it has already forwarded the claim there. Follow up with the behavioral health plan rather than resubmitting.

Quick facts

Code
CO-300 (CARC 300)
Status
Active In use since July 1, 2019.
Code set
Claim Adjustment Reason Codes (CARC)
Group codes
  • CO (Contractual Obligation): The usual group. The medical plan pays nothing; the balance waits for the behavioral health plan and isn't billed to the patient yet.
  • OA (Other Adjustment): Some payers use OA because the claim is being transferred to another benefit administrator.
Official description
Claim received by the Medical Plan, but benefits not available under this plan. Claim has been forwarded to the patient's Behavioral Health Plan for further consideration.
X12 Claim Adjustment Reason Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What CO-300 means

CARC 300 says the claim was received by the medical plan, but benefits are not available under this plan, and the claim has been forwarded to the patient’s behavioral health plan. The patient’s mental health and substance use benefits are administered separately, and the medical plan has already passed the claim to that administrator.

Behavioral health carve-outs are common in employer plans and managed Medicaid. The member carries one card, but claims for psychotherapy, psychiatric evaluation, or substance use treatment go to a different company with its own payer ID and rules. When they’re sent to the medical plan instead, it may forward them, producing CO-300, or tell you to rebill, producing CO-301.

Forwarding is a convenience, but it does not guarantee smooth processing. The behavioral health plan may still deny the forwarded claim for authorization, network status, or missing information.

Common causes

  • Mental health or substance use services billed to the medical payer ID instead of the behavioral health vendor’s.
  • Card shows only the medical plan, with the carve-out listed on the back or not at all.
  • Eligibility check run only against the medical plan.
  • Plan changed vendors mid-year and the practice’s payer setup wasn’t updated.

How to handle it

  1. Hold the balance and don’t bill the patient.
  2. Identify the behavioral health vendor from the card back, the medical plan, or the eligibility response.
  3. Confirm receipt of the forwarded claim with the vendor after a reasonable interval.
  4. Check credentialing and authorization requirements with the vendor for this and future visits.
  5. If the vendor has no record, submit the claim directly, keeping the CO-300 remittance as proof of original filing.
  6. Update the patient’s insurance record so future claims go straight to the vendor.

How to prevent it

  • Verify behavioral health benefits specifically, not just medical eligibility, before the first session.
  • Store the carve-out as a separate payer in your billing system with its own payer ID.
  • Credential with the major behavioral health vendors for the plans your patients carry.
  • Track forwarded claims until paid. See eligibility and COB denials.

Specialty notes

Outpatient therapy practices, psychiatry groups, and substance use treatment programs see CO-300 most. Medical practices offering integrated behavioral health should confirm whether those services bill to the medical plan or the carve-out for each payer.

Remark codes that may appear with CO-300

  • N130 (Consult plan benefit documents/guidelines for information about restrictions for this service.): Points to plan documents that assign mental health and substance use services to a separate plan.
  • CO-301 (Claim received by the Medical Plan, but benefits not available under this plan.): Same routing, but the claim wasn't forwarded; you must submit it to the behavioral health plan.
  • CO-298 (Claim received by the medical plan, but benefits not available under this plan.): The medical plan forwarded the claim to a vision plan instead.
  • CO-109 (Claim/service not covered by this payer/contractor.): Not covered by this payer; send to the correct payer.
  • CO-197 (Precertification/authorization/notification/pre-treatment absent.): Authorization absent, which may follow if the behavioral health plan requires its own approval.

CO-300 FAQ

What is a behavioral health carve-out?

An arrangement where a health plan or employer contracts with a separate company, often called a managed behavioral health organization, to administer mental health and substance use benefits. It has its own network, payer ID, and rules.

Do I need to resubmit after CO-300?

Usually not right away. The claim was forwarded. Confirm with the behavioral health plan that it received the claim before sending anything, to avoid duplicate denials.

Will I be paid in-network?

Only if you're credentialed with the behavioral health vendor. Participation with the medical plan doesn't always carry over to the carve-out network.

What if the forwarded claim gets denied for authorization?

Carve-out vendors often have their own authorization and notification rules. Work that denial with the behavioral health plan and set up authorizations for future visits.