CO 213 denial code

Claim adjustment reason code 213. Often reported as CO 213.

Self-referral rule violation

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 213 means

The claim was denied because the referral appears to break physician self-referral law or the payer's self-referral policy.

The payer thinks the referring physician has a financial interest in the entity that provided the service, in a way that law or policy does not allow.

This is a compliance issue, not a routine billing fix. Involve your compliance team before resubmitting or appealing.

Group codes seen with 213

On a remittance, 213 comes after a group code. These are the ones it is most often reported with:

• CO 213 (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 referring physician has an ownership or compensation tie to the entity that billed.
• The arrangement may fit an exception, but the claim or records did not show it.
• The referring provider on the claim was entered wrong, creating a false appearance of self-referral.

What to do next

1. Confirm the referring provider listed on the claim is correct.
2. Send the claim to your compliance team to review the financial relationship and any exception.
3. Appeal with documentation of the exception only after compliance has signed off.

Related codes

• 16 (reason code) Missing information or billing error
• 96 (reason code) Service not covered by the plan