OA B11 denial code

Claim adjustment reason code B11. Often reported as OA B11 or CO B11.

Sent to the proper payer

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 Nov 11, 2026.

What B11 means

This payer is not responsible for the claim and has forwarded it, or says it belongs, to a different payer or processor.

B11 means you billed the wrong place. The payer either transferred the claim to the correct payer or processor, or is telling you the claim is outside its jurisdiction or contract.

Do not assume the claim was forwarded. Confirm whether another payer has it, and submit it there yourself if not.

Group codes seen with B11

On a remittance, B11 comes after a group code. These are the ones it is most often reported with:

• OA B11 (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.
• CO B11 (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.

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

• The service is covered by a carve out vendor, such as a separate behavioral health or pharmacy manager.
• The claim was sent to the wrong regional contractor or plan for the provider's location.
• The patient's coverage moved to another plan or a managed care organization.

What to do next

1. Check the remittance and any remark codes for the name of the payer that should process the claim.
2. Verify the patient's current coverage and any carve out vendors for the service.
3. Submit the claim to the correct payer if it was not forwarded automatically, keeping proof of the original filing date.

Related codes

• 109 (reason code) Not covered by this payer, send elsewhere
• 22 (reason code) Another payer may be primary
• B9 (reason code) Patient is enrolled in hospice