CO-304: Medical Plan Claim — Submit to Hearing Plan
Resubmit to the hearing plan. Do not collect from the patient.
What Does CO-304 Mean?
The medical plan treats this as a contractual adjustment. The provider must resubmit to the hearing plan and cannot collect from the patient for this denial.
CARC 304 appears when the medical plan determines the billed service falls under hearing coverage rather than the medical benefit. Insurers that use hearing benefit carve-outs separate hearing services from the medical plan. When the medical plan identifies a claim as hearing-related — such as audiometry, hearing aid fitting, or cochlear implant services — it denies coverage and directs the provider to submit to the hearing plan.
This code functions similarly to CARC 301 (behavioral health redirection) but applies specifically to hearing services. It can also appear when procedure or diagnosis codes on the claim cause the medical plan's classification logic to categorize the service as hearing-related, even if the provider views the service as primarily medical.
Common Causes
| Cause | Frequency |
|---|---|
| Service classified as hearing-related Medical plan determined the service falls under hearing coverage and the provider must submit to the hearing plan | Most Common |
| Hearing benefit carve-out Patient's plan uses a hearing benefit carve-out where the medical plan does not process hearing-related claims | Most Common |
| Incorrect plan submission Provider submitted hearing services (audiometry, hearing aids, cochlear implant services) to the medical plan instead of the hearing plan | Common |
| Missing pre-authorization from hearing plan Required preauthorization was not obtained from the hearing plan before services were rendered | Common |
| Incorrect coding triggering hearing classification Diagnosis or procedure codes on the claim caused the medical plan to classify the service as hearing-related | Common |
How to Resolve
- Identify the patient's hearing plan by checking the insurance card or contacting the medical plan
- Obtain the correct payer ID and submission details for the hearing plan
- Resubmit the claim to the patient's hearing plan with all required documentation
- If you believe the service is medical and not hearing-related, appeal with clinical documentation
- Verify whether pre-authorization is required by the hearing plan before resubmission
Appeal with clinical documentation showing the service is medical and not hearing-related. Include physician notes, procedure details, and diagnosis codes that support medical plan coverage.
Common RARC Pairings
The RARC code tells you exactly what triggered the CO-304:
| RARC | Description |
|---|---|
| N527 | Payment has been issued to another plan/entity for this claim. Contact the medical plan to obtain hearing plan details and resubmit → |
| N381 | Alert: Consult your contractual agreement for restrictions, billing, and payment information. Review the payer contract to identify the hearing plan for resubmission → |
How to Prevent CO-304
- Verify whether the patient has a separate hearing plan during registration
- Conduct eligibility checks to identify hearing carve-outs before rendering services
- Train staff on the distinction between medical plan and hearing plan coverage
- Use electronic claim routing systems that direct hearing claims to the correct plan
- Maintain a list of common hearing-related CPT and diagnosis codes for proper plan routing
Also Filed As
The same CARC 304 may appear with different Group Codes:
Related Denial Codes
Sources
- https://x12.org/codes/claim-adjustment-reason-codes
- https://www.mdclarity.com/denial-code/304
- https://www.cms.gov/medicare/payment/prospective-payment-systems
- Codes maintained by X12. Visit x12.org for official definitions.