OA-23: Impact of Prior Payer Adjudication (COB)

OA (Other Adjustment)

What is OA-23?

OA-23 is an Other Adjustment code indicating the payment was adjusted based on the primary payer's adjudication under coordination of benefits (COB). This is an informational adjustment, not a denial. The secondary payer processed the claim and applied the primary payer's payment and adjustments before calculating their own payment.

Why Does OA-23 Occur?

  1. Standard COB processing. The secondary payer reduced their payment based on what the primary payer already paid. This is normal COB behavior.
  2. Primary payer paid more than expected. The secondary payer's adjustment reflects that the primary covered most or all of the allowed amount.
  3. Primary payer denied the claim. The secondary payer may adjust based on the primary's denial, depending on the secondary plan's COB terms.

How to Fix OA-23 Denials

  1. Review the EOB from both the primary and secondary payers. Confirm the secondary correctly applied the primary's payment and adjustments.
  2. If the combined payment from both payers equals the total allowed amount, no action is needed. OA-23 is working as intended.
  3. If the calculation is incorrect, contact the secondary payer with both EOBs showing the discrepancy.
  4. If the primary payer denied the claim incorrectly, resolve the primary denial first, then resubmit to the secondary.

OA-23 by Payer

Payer Common RARC Appeal Deadline Notes
UnitedHealthcare N/A N/A COB adjustment. No appeal needed unless calculation is incorrect.
Anthem N/A N/A COB adjustment. No appeal needed unless calculation is incorrect.
Aetna N/A N/A COB adjustment. No appeal needed unless calculation is incorrect.
Cigna N/A N/A COB adjustment. No appeal needed unless calculation is incorrect.
Medicare N/A N/A COB adjustment informational. No appeal needed.

Related CARC Codes

If you are seeing OA-23, check these related codes: CO-22 (coordination of benefits required), CO-44 (subscriber not eligible), PR-1 (deductible).

Common Questions About OA-23

Is OA-23 a denial?

No. OA-23 is an informational adjustment showing how the secondary payer calculated their payment based on the primary's adjudication. It is standard coordination of benefits processing.

Do I need to appeal OA-23?

Usually not. OA-23 is working as designed. Only take action if the secondary payer's calculation is incorrect based on the primary's EOB.

Altair catches OA-23 denials before submission with automated COB tracking. See how pre-submit claim scoring works.

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This reference is for informational purposes. Always verify against current payer policies and CMS guidelines. Last updated: 2026-03-09.