OA-23: Impact of Prior Payer Adjudication

What Does OA-23 Mean?

OA-23 is the standard and predominant pairing for this code. The OA designation identifies this as an administrative adjustment — the secondary payer is not claiming a contractual violation or assigning patient responsibility. They are simply accounting for the primary payer's prior adjudication in their payment calculation. The OA grouping means the adjustment amount is neither a contractual write-off nor a patient balance by itself; you need to look at the complete picture of both payers' adjudications to determine who (if anyone) still owes money.

When CARC 23 appears on a remittance, the secondary payer is telling you that their payment calculation was influenced by the primary payer's prior adjudication of the same claim. This code almost exclusively pairs with Group Code OA (Other Adjustment) because the adjustment is an administrative byproduct of the COB process — it is not a provider contractual issue or a patient responsibility determination at this stage.

The most common scenario is straightforward: the primary payer paid at or above the secondary payer's allowable rate, leaving nothing additional for the secondary to pay. The OA-23 adjustment reflects the difference between what the secondary would have paid independently and what the primary already covered. Less commonly, OA-23 surfaces when the primary payer made errors — underpayments, incorrect adjustments, or outright denials — that cascade into the secondary's adjudication. The secondary payer simply factors in the primary's outcomes when calculating their own payment.

Resolving OA-23 requires working backward through the primary payer's EOB. If the primary paid correctly and the secondary's adjustment math checks out, the remaining balance (if any) is the patient's responsibility. If the primary underpaid or erred, the fix starts there — you need to dispute with the primary payer first, and once the primary corrects their adjudication, the secondary will reprocess based on the updated primary EOB. Chasing the secondary payer for a higher payment is rarely productive when the root cause is the primary payer's adjudication.

Common Causes

How to Resolve

Audit the primary payer's EOB, verify the secondary's adjustment is mathematically correct, and address any primary payer errors before requesting secondary reprocessing.

1. Audit the primary payer's EOB Review the primary payer's payment, adjustments, and reason codes. Verify the primary processed the claim correctly per your contracted rates.
2. Verify the secondary's OA-23 calculation Compare the secondary payer's allowable rate against the primary's payment. If the math is correct and no additional payment is due, post the adjustment.
3. Dispute primary payer errors upstream If the primary underpaid, correct the issue with the primary payer first. Submit the revised primary EOB to the secondary for reprocessing.
4. Determine and bill any patient responsibility After both payers have adjudicated, calculate the patient's remaining financial obligation and bill accordingly.

Common RARC Pairings

The RARC code tells you exactly what triggered the OA-23:

How to Prevent OA-23

• Always wait for the primary payer to fully adjudicate before submitting secondary claims — never submit to the secondary before you have the primary's EOB
• Audit primary payer EOBs for underpayments or errors before forwarding to the secondary — catching mistakes early prevents cascading OA-23 issues
• Verify COB order with both payers before rendering services to ensure the correct billing sequence from the start
• Submit primary claims promptly to avoid delays in secondary processing and potential timely filing issues with the secondary payer
• Maintain current contracted rate schedules for both primary and secondary payers to quickly verify OA-23 adjustment accuracy

General Prevention

• Always wait for the primary payer to fully adjudicate the claim before submitting to the secondary payer, and always attach the primary EOB to the secondary claim
• Verify patient eligibility and COB order with both payers before rendering services to ensure correct billing sequence
• Audit primary payer EOBs for errors or underpayments before accepting and forwarding to the secondary — catching primary payer mistakes early prevents cascading OA-23 adjustments
• Submit claims promptly to the primary payer to avoid delays in the secondary payer's processing timeline and potential timely filing issues
• Maintain accurate records of contracted rates with both primary and secondary payers to quickly identify when OA-23 adjustments are incorrect

Also Filed As

The same CARC 23 may appear with different Group Codes:

Related Denial Codes