CARC Code
21
No-Fault Carrier Liability
The insurance company is denying this claim because the injury or illness should be paid by a no-fault insurance carrier instead. This typically applies when another type of insurance (like auto insurance in a car accident) is responsible for covering the medical treatment.
cobHow to resolve this denial
Submit claim to the no-fault insurance carrier
- 1
Review the remittance advice to confirm the adjustment amount is accurate
- 2
Verify the contractual write-off against your fee schedule
- 3
Post the adjustment to the patient account
- 4
Do not balance bill the patient for this contractual reduction
- 5
Document the adjustment in your billing system
▶✓ Pre-action checklist — verify before contacting the payer
Review the full remittance advice (ERA/EOB) for additional RARC codes that explain the denial.
Verify the claim was submitted with correct patient eligibility and benefit information.
Check if this denial applies to a specific line item or the entire claim.
▶More about OA-21 — stats, related codes, appeal template
99%
Recovery Rate
1-3 days
Avg. Resolution
Medium
Difficulty
Rare
Frequency
Payer-Specific Notes
How major payers handle CARC 21 by specialty.
UnitedHealthcare
Review UHC's online claim status tool for additional detail on this adjustment.
Appeal Letter Template
Generic appeal template for CARC 21 denials.
We are submitting a formal appeal for claim [CLAIM_NUMBER] for patient [PATIENT_NAME], date of service [DOS]. This claim was denied/adjusted with CARC 21 indicating: "This injury/illness is the liability of the no-fault carrier.." We have reviewed the claim and are providing the attached documentation to support reconsideration. [SUPPORTING_DOCUMENTATION]. Please reconsider payment per the terms of our contract.
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