CARC 23: Impact of Prior Payer(s) Adjudication

What it means

This code shows up when a claim has already been processed by another payer (like a primary insurance) before reaching the payer that issued this remark. The adjustment amount reflects what the prior payer already paid or adjusted, and it's being factored into how this payer calculates its own payment. It's not necessarily a denial of the whole claim—it's more of an explanatory code showing how coordination of benefits (COB) affected the final allowed amount or payment.

Common causes

Claim involves coordination of benefits (COB) with a primary, secondary, or tertiary payer
Primary payer already paid a portion of the charges, and this payer is adjusting its payment accordingly
Primary payer applied a contractual adjustment or discount that's being passed through
Patient has multiple active insurance policies and claims were filed in sequence
Medicare or another payer is secondary and calculating payment based on what the primary already covered

How to fix it

Review the EOB/ERA from the prior (primary) payer to confirm what was paid and adjusted
Verify the claim was submitted to the secondary/tertiary payer with the primary payer's payment and adjustment information correctly included (often via COB segments or attached EOB)
Check that the claim form includes the correct payer order (primary, secondary, tertiary)
Confirm the patient's insurance information is current and payer sequencing is accurate in your system
If the secondary payment looks incorrect, recalculate expected reimbursement based on COB rules (e.g., non-duplication, standard COB) to see if the payer applied them correctly
Contact the current payer if the adjustment amount doesn't match what you'd expect based on the prior payer's EOB

Appeal / resubmit

If you believe the secondary or tertiary payer miscalculated the adjustment based on the prior payer's EOB, gather both EOBs/ERAs and compare them line by line against the payer's COB methodology (standard COB vs. non-duplication of benefits). Submit an appeal with both EOBs attached, clearly showing the discrepancy. Note that this code alone doesn't indicate an error—it's often informational—so appeals are only appropriate when the resulting payment appears incorrect.

Related codes

Frequently asked

Does CARC 23 mean my claim was denied?

Not necessarily. This code is often informational, explaining that the payment or adjustment reflects what a prior payer already paid or adjusted. The claim may still be paid in part or in full.

What should I check first when I see this code?

Start by reviewing the EOB from the prior payer to understand what was already paid or adjusted, then compare it to what the current payer processed.

Why does this happen so often with secondary insurance claims?

When a patient has multiple insurance plans, claims are typically processed in sequence. The secondary or tertiary payer factors in what the primary payer already paid, which generates this code to explain the adjustment.

More free billing tools: all denial codes · denial lookup · Medicare fee calculator

This content is informational only and does not constitute billing or legal advice. Always verify current payer policies and consult a qualified billing or compliance professional for specific guidance.