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CO-B11 Denial Code: Claim Transferred to the Proper Payer

CO-B11 means this payer or processor doesn't handle the claim, and it has transferred it to the payer or processor it believes is correct. You don't need to refile right away; track the claim with the receiving payer.

Quick facts

Code
CO-B11 (CARC B11)
Status
Active In use since January 1, 1995.
Code set
Claim Adjustment Reason Codes (CARC)
Group codes
  • CO (Contractual Obligation): The usual group. No payment from this payer and no patient liability; the claim moves to another processor.
  • OA (Other Adjustment): Some payers use OA, since the amount is simply being handed off to another processor.
Official description
The claim/service has been transferred to the proper payer/processor for processing. Claim/service not covered by this payer/processor.
X12 Claim Adjustment Reason Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What CO-B11 means

CARC B11 says the claim or service has been transferred to the proper payer or processor for processing. Claim or service not covered by this payer or processor. Unlike most denials, this one comes with a helpful step already taken: the payer recognized the claim belongs elsewhere and passed it along.

This mostly happens between related processors. Examples include Medicare contractors (Part A/B contractors and DME contractors), Blue Cross Blue Shield plans routing claims between home and host plans, and health plans that use separate vendors for behavioral health, labs, or other carved-out services.

Common causes

  • Claim sent to the wrong Medicare contractor, such as supplies billed to an A/B contractor instead of a DME contractor, or a claim filed in the wrong jurisdiction.
  • Service area rules for labs and DME, where the correct processor depends on where a specimen was collected or where equipment was received.
  • Blue plan routing between home and host plans.
  • Carve-out vendors for behavioral health, vision, or other services administered separately.

How to handle it

  1. Note the date and payer on the CO-B11 remittance.
  2. Check the receiving payer’s status after a reasonable time, using its portal or a claim status inquiry.
  3. If the claim arrives, track it to adjudication there. No further action is needed with the first payer.
  4. If it never arrives, submit the claim directly to the correct payer, keeping the CO-B11 ERA as proof of original filing.
  5. Update your routing so future claims go straight to the right processor.

How to prevent it

  • Maintain payer ID and routing tables, including which Medicare contractor handles which services.
  • Identify carve-out vendors during eligibility verification. See eligibility and COB denials.
  • Apply service-area rules for labs and DME based on specimen collection or delivery location.
  • Scrub payer selection before submission. A Claims Validator can check that the payer ID fits the service type.

Specialty notes

DME suppliers and independent labs see CO-B11 most, because the correct processor often depends on location or item type. Behavioral health practices see it when a medical plan forwards claims to its behavioral health carve-out.

Remark codes that may appear with CO-B11

  • N104 (This claim/service is not payable under our claims jurisdiction area.): Not payable under this contractor's jurisdiction; identifies that another Medicare contractor handles it.
  • N557 (This claim/service is not payable under our service area.): The claim belongs to the payer or plan in whose service area the specimen was collected.
  • N559 (This claim/service is not payable under our service area.): The claim belongs to the payer or plan in whose service area the ordering physician is located.
  • CO-109 (Claim/service not covered by this payer/contractor.): Not covered by this payer, and you must send the claim to the correct payer yourself.
  • OA-22 (This care may be covered by another payer per coordination of benefits.): Another payer may be primary under coordination of benefits.
  • OA-18 (Exact duplicate claim/service (Use only with Group Code OA except where state workers' compensation regulations requires CO)): Exact duplicate, which can happen if you refile while the transferred claim is still processing.
  • CO-B9 (Patient is enrolled in a Hospice.): Patient enrolled in hospice, another case where a different entity is responsible.

CO-B11 FAQ

What's the difference between CO-B11 and CO-109?

With CO-B11 the payer forwards the claim for you. With CO-109 it doesn't; you must identify the correct payer and submit the claim yourself.

Should I resubmit a CO-B11 claim?

Not immediately. Check the receiving payer for the claim first. Resubmitting too soon can create duplicate denials. If it never arrives, file with the correct payer directly.

Where does CO-B11 come up most often?

In Medicare, when a claim goes to the wrong contractor, such as a DME item sent to an A/B contractor, or in Blue plan arrangements where the claim is routed to the home or host plan.

Does the transfer protect timely filing?

Often the original receipt date is used, but rules vary. Keep the ERA showing CO-B11 as proof of when the claim was first filed.