Skip to main content

CO-305 Denial Code: Medical Plan Forwarded Claim to Hearing

CO-305 means the patient's medical plan has no benefit for the billed services, usually hearing aids or related services, and has already forwarded the claim to the patient's hearing plan. Monitor the hearing plan's response instead of resubmitting right away.

Quick facts

Code
CO-305 (CARC 305)
Status
Active In use since March 1, 2022.
Code set
Claim Adjustment Reason Codes (CARC)
Group codes
  • CO (Contractual Obligation): The usual group. The medical plan pays nothing; the balance waits on the hearing plan and isn't billed to the patient yet.
  • OA (Other Adjustment): Some payers use OA because the claim is being transferred rather than finally denied.
Official description
Claim received by the medical plan, but benefits not available under this plan. Claim has been forwarded to the patient's hearing plan for further consideration.
X12 Claim Adjustment Reason Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What CO-305 means

CARC 305 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 hearing plan. The medical plan identified the services as belonging to a separate hearing benefit and sent the claim there on your behalf.

This is the forwarded twin of CO-304. The practical difference is timing and duplicates: with CO-305 the hearing plan should already have the claim, so sending another one can create a duplicate denial. Your job is to track the handoff.

Forwarding typically happens when the medical plan and hearing administrator exchange claim data, for instance within a Medicare Advantage plan that contracts out its supplemental hearing benefit.

Common causes

  • Hearing aids, fittings, or device follow-up billed to the medical plan.
  • Plans with supplemental hearing benefits run by a separate administrator.
  • Registration captured only the medical plan’s payer ID.

How to handle it

  1. Post the zero-pay medical remittance and keep the balance open.
  2. Follow up with the hearing plan after a reasonable interval to confirm receipt.
  3. Send requested documentation promptly, such as audiograms or device information.
  4. If the hearing plan can’t find the claim, submit directly with proof of the original filing date.
  5. After the hearing plan pays, bill the patient only for the responsibility it assigns and any agreed amounts.
  6. Appeal to the medical plan only if the service was a covered medical service, such as diagnostic testing ordered for a medical condition.

How to prevent it

  • Verify hearing benefits and the administrator before fitting devices.
  • Bill devices directly to the hearing plan once you know it exists.
  • Track forwarded claims in a work queue. An ERA Analyzer can list claims with CO-305 still waiting on a second payer.

Specialty notes

Audiologists and hearing aid dispensers serving Medicare Advantage members see forwarded claims most often, because many MA plans deliver hearing benefits through a third-party administrator.

Remark codes that may appear with CO-305

  • N130 (Consult plan benefit documents/guidelines for information about restrictions for this service.): Points to medical plan documents assigning hearing services to a separate benefit.
  • CO-304 (Claim received by the medical plan, but benefits not available under this plan.): Same routing, but the medical plan did not forward the claim; you must submit it.
  • 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-300 (Claim received by the Medical Plan, but benefits not available under this plan.): The medical plan forwarded the claim to a behavioral health plan.
  • OA-18 (Exact duplicate claim/service (Use only with Group Code OA except where state workers' compensation regulations requires CO)): Exact duplicate, which can result if you resubmit a claim that was already forwarded.

CO-305 FAQ

What should I do after CO-305?

Record the date, then confirm with the hearing plan that it received the forwarded claim. Wait for its remittance before billing the patient or resubmitting.

Will the hearing plan need more information?

Often. Hearing administrators may require device details, audiogram results, a medical clearance or order, or their own authorization number. Be ready to send these.

What if I'm not in the hearing plan's network?

The claim may be processed out-of-network or denied, depending on the program. Check the hearing plan's rules and discuss any resulting balance with the patient according to your agreement.

What if the hearing plan has no record of the claim?

Submit it directly to the hearing plan and keep the medical remittance showing CO-305 as proof of original filing.

Does CO-305 affect diagnostic hearing tests?

Usually not. Diagnostic audiology ordered for a medical reason often stays with the medical plan. CO-305 typically applies to devices and related services the hearing benefit covers.