OA-23 is not a denial. It shows up on secondary claims and represents the impact of what the primary payer already paid or adjusted. The secondary payer is telling you that amount is accounted for. What matters is the patient responsibility left after both payers.
1. What OA-23 means
- OA (Other Adjustment): neither a contractual write-off nor patient responsibility.
- 23: the impact of prior payer(s) adjudication, including payments and adjustments.
The secondary payer uses OA-23 to show the portion of the charge it did not consider because the primary payer already handled it.
2. How to read OA-23 on a secondary claim
| Line on the secondary remittance | Example |
|---|---|
| Billed charge | $200 |
| OA-23 (impact of the primary payer's payment and adjustments) | $170 |
| Secondary payer paid | $25 |
| PR (patient responsibility left) | $5 |
Post the secondary payment and the remaining PR amount. The OA-23 amount is not a write-off you choose to take and not something to bill anyone for. It reflects the primary payer's processing.
3. When the secondary pays nothing
A secondary payment of $0 with OA-23 often means the primary payer already paid as much as or more than the secondary would have allowed. Depending on the secondary plan's coordination method, it pays only up to its own allowed amount, minus what the primary paid. That can be correct.
4. When OA-23 points to a problem
- The primary payment information sent was wrong or incomplete, so the secondary calculated from bad numbers. Send a corrected claim with the right primary remittance data.
- The primary was billed incorrectly, for example the wrong plan was treated as primary. See CO-22.
- The primary later reprocessed the claim. The secondary needs to be rebilled with the updated amounts.
Related: PR-1, CO-45, and the full CARC and RARC codes list.
5. Payer-by-payer: what the secondary should pay
| Payer | What to know |
|---|---|
| Medicare as secondary | Bill Medicare as secondary payer (MSP) with the primary's payment and adjustments on the claim. Medicare pays the lowest of: what it would have paid as primary, the remaining charge, or the amount up to its allowed amount. When the primary paid more than Medicare allows, Medicare pays $0. |
| Medigap and crossovers | Most Medigap and many Medicaid claims cross over from Medicare automatically. Check the Medicare remittance for a crossover remark code before billing the secondary yourself, or you may create a duplicate. |
| Medicaid as secondary | Medicaid usually pays up to its own allowed amount, minus what the primary paid. Because Medicaid rates are low, a $0 payment with OA-23 is common and is usually correct. |
| Commercial secondary | The plan's COB method decides the payment. Traditional COB can pay up to the full balance. Non-duplication or carve-out methods often pay $0 when the primary already paid what the secondary would have. The method is in the member's plan documents. |
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