Official CARC description: “The impact of prior payer(s) adjudication including payments and/or adjustments.” Here’s what it actually means, why it fires, and how to get the claim paid.
A secondary-claim code: this payer reduced its payment because of what the primary already paid/adjusted. It's the COB math line, not a denial — audit it rather than appeal it.
Liability group: CO = Contractual Obligation — the provider absorbs it — the amount cannot be billed to the patient. If the denial is wrong, the money is recovered by correcting or appealing the claim, not by balance-billing.
Verify the primary payment/adjustment amounts transmitted correctly
Check the secondary's allowed-amount logic against its COB method (full vs non-duplication)
If primary data was wrong: corrected secondary claim with accurate COB fields
Post to the right adjustment buckets so patient statements stay correct
Appeal only when the secondary applied the wrong COB methodology for the plan type — attach both EOBs and the plan's COB provision.
Fill in the denial facts — use placeholders, never real patient data (the letter keeps [PATIENT NAME]-style fields so you can merge real details privately). A payer-ready draft with an enclosure checklist comes back in ~20 seconds.
Your appeal letter draft will appear here.
The impact of prior payer(s) adjudication including payments and/or adjustments. In practice: A secondary-claim code: this payer reduced its payment because of what the primary already paid/adjusted. It's the COB math line, not a denial — audit it rather than appeal it.
CO stands for Contractual Obligation — the provider absorbs it — the amount cannot be billed to the patient. If the denial is wrong, the money is recovered by correcting or appealing the claim, not by balance-billing.
Appeal only when the secondary applied the wrong COB methodology for the plan type — attach both EOBs and the plan's COB provision.