CARC 21 Active

OA-21: No-Fault Carrier Responsible

TL;DR

Adjustment in a COB or secondary payer context. Review the coordination of benefits details to determine the responsible party.

Action
Resubmit
Who Pays
Depends
Appeal
Yes
Patient Impact
Indirect
Disclaimer
This content is for informational purposes only and does not constitute professional billing advice. Always verify information against your payer contracts and current coding guidelines. Consult a certified billing specialist for specific claim issues.

What Does OA-21 Mean?

With OA (Other Adjustments), CARC 21 typically appears in a coordination of benefits (COB) context. Health plan redirects to no-fault carrier in coordination context. The financial responsibility depends on the specific arrangement between payers — review the primary payer's EOB and the COB terms to determine the correct course of action.

CARC 21 indicates no-fault carrier responsible. The payer determined that the service or a portion of it does not meet coverage criteria under the patient's current plan benefits or the applicable coverage rules.

Common scenarios that trigger this adjustment include: injury from auto accident in a no-fault insurance state billed to health plan instead of PIP/no-fault carrier; Personal Injury Protection (PIP) benefits have not been exhausted, and the no-fault carrier should pay first; Health plan's system flagged the claim as no-fault based on diagnosis or condition codes. The group code paired with CARC 21 determines who bears the financial responsibility — CO places it on the provider as a contractual obligation, OA indicates a coordination of benefits or other payer adjustment, PR shifts it to the patient.

Common Causes

Cause Frequency
COB redirect to no-fault Health plan redirects to no-fault carrier in coordination context Most Common

How to Resolve

  1. Review the coordination of benefits Examine the OA-21 adjustment to understand how it fits within the primary/secondary payer relationship or other multi-payer context.
  2. Verify primary payer adjudication Review the primary payer's EOB to understand the basis for the secondary payer's OA adjustment.
  3. Determine the responsible party Based on the COB review, identify whether the adjustment should be absorbed, billed to another payer, or if additional documentation is needed.
  4. Appeal or resubmit if needed Appeal with documentation of PIP exhaustion or proof that no-fault does not apply.
  5. Follow up Monitor the claim status and take additional action as needed based on the COB determination.
Appeal Guide

Appeal with documentation of PIP exhaustion or proof that no-fault does not apply.

Common RARC Pairings

The RARC code tells you exactly what triggered the OA-21:

RARC Description
N36 Claim must meet primary payer requirements Submit to no-fault carrier →

How to Prevent OA-21

Also Filed As

The same CARC 21 may appear with different Group Codes:

CO-21 PR-21

Related Denial Codes

OA-19 — Workers' Compensation Claim OA-20 — Liability Carrier Responsible OA-22 — Coordination of Benefits - Another Payer May Cover OA-23 — Prior Payer Adjudication Impact OA-26 — Expenses Incurred Prior to Coverage

Sources

  1. https://x12.org/codes/claim-adjustment-reason-codes
  2. https://revenuecyclemgmt.com/claim-adjustment-reason-codes/
  3. https://www.rivethealth.com/blog/carcs-rarcs-claim-adjustment-remittance-advice-codes
  4. Codes maintained by X12. Visit x12.org for official definitions.