CO 304 denial code
Claim adjustment reason code 304. Often reported as CO 304 or OA 304.
Medical plan: bill the hearing plan
Unofficial reference. This is our own plain-English explanation, not the official code text. Payer rules differ. Verify with the payer and the official X12 code list. AlphaPrefix is not affiliated with X12, CMS or any payer. Data last updated .
What 304 means
Send this service to the patient's hearing benefit; the medical plan has no benefit for it and did not forward the claim.
Some plans cover hearing aids and related services through a separate hearing benefit or vendor. The medical payer says this service belongs there and did not forward the claim. Code 305 is used when it was forwarded.
Diagnostic hearing tests for a medical problem may still be medical, so check the coding.
Group codes seen with 304
On a remittance, 304 comes after a group code. These are the ones it is most often reported with:
- CO 304 (Contractual Obligation): The provider's side of the ledger. The reduction comes from the payer contract or a rule the provider has to follow, and the patient normally cannot be billed for it.
- OA 304 (Other Adjustment): Used for adjustments that are neither the provider's contractual write-off nor the patient's share. It often appears with coordination of benefits, for example when another payer already paid.
The payer chooses the group code for each adjustment, so the same reason code can appear with another group code on your remittance. Read the two together. More about group codes.
Common causes
- Hearing aids or fitting services were billed to the medical plan.
- The plan carves out hearing benefits to a separate vendor.
- Routine hearing services were billed under medical coverage.
What to do next
- Identify the patient's hearing benefit and vendor.
- Submit the claim to the hearing plan with its required format.
- If the service was diagnostic for a medical condition, review the coding and resubmit to medical.
Related codes
- 305 (reason code) Medical plan forwarded to hearing plan
Source
Official wording: X12 Claim Adjustment Reason Codes list. The explanation on this page is our own plain-English wording, not the X12 text.
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