CARC Code 23
The impact of prior payer adjudication has been applied, including payments and/or adjustments.
What this denial means
When you see CARC code 23 on your Explanation of Benefits (EOB), it means your insurer has denied the claim with the following reason: the impact of prior payer adjudication has been applied, including payments and/or adjustments.
This code is one of the most common denial reasons in the CARC system and appears across both employer-sponsored and ACA marketplace plans. How you respond depends on whether the denial is a patient-side or provider-side issue.
Can you appeal this?
Yes — this denial is patient-appealable. Confirm the primary payer's EOB is accurate and submit it with your appeal; if the secondary payer's calculation of its obligation is incorrect, dispute the coordination-of-benefits math with your plan documents.
Applicable federal regulations:
ERISA plans (employer-sponsored)
- ERISA § 503
- 29 CFR § 2560.503-1(h)
ACA plans (marketplace / individual)
- PHS Act § 2719
- 45 CFR § 147.136(b)
Your insurer's legal team is bound by these regulations. An appeal letter that cites them directly demands a specific, documented response.
What to include in your appeal
Gather as many of these supporting documents as apply to your denial:
- –Explanation of Benefits (EOB)
- –Doctor's letter of medical necessity
- –Clinical notes and records from your provider
- –Prior authorization record (if applicable)
- –Summary of Benefits and Coverage (SBC)
See our submission guide for full instructions on each document and how to submit your appeal.
Related reading
Not legal or medical advice. Rebuttal is a document drafting tool, not a law firm. Review your letter before submitting and consult a licensed professional for legal questions specific to your plan.