OA 23 denial code

Claim adjustment reason code 23. Often reported as OA 23.

Prior payer payment affected this claim

Unofficial reference. This is our own plain-English explanation, not the official code text. Payer rules differ. Verify with the payer and the official X12 code list. AlphaPrefix is not affiliated with X12, CMS or any payer. Data last updated Nov 11, 2026.

What 23 means

This payment was reduced because of what an earlier payer already paid or adjusted on the claim.

This code shows up on secondary and later claims. The payer looked at the primary payer's payment and adjustments and reduced its own payment so the combined total stays within its rules.

It is only used with group code OA. It is not a denial on its own, but the amount should make sense when you line up both remittances. A mismatch usually means the prior payer data on the claim was wrong.

Group codes seen with 23

On a remittance, 23 comes after a group code. These are the ones it is most often reported with:

• OA 23 (Other Adjustment): Used for adjustments that are neither the provider's contractual write-off nor the patient's share. It often appears with coordination of benefits, for example when another payer already paid.

The payer chooses the group code for each adjustment, so the same reason code can appear with another group code on your remittance. Read the two together. More about group codes.

Common causes

• The primary payer paid most or all of the allowed amount, leaving little for the secondary.
• The secondary payer's allowed amount is lower than the primary's, so it owed less or nothing.
• The prior payer amounts or adjustment codes on the secondary claim were entered incorrectly.

What to do next

1. Put the primary and secondary remittances side by side and check the math.
2. Confirm the prior payer's paid amount and adjustment codes were sent correctly on the secondary claim.
3. Send a corrected secondary claim if the prior payer data was wrong.
4. Move any balance to the next payer or the patient only after confirming what each group code on the claim assigns.

Related codes

• 22 (reason code) Another payer may be primary
• 45 (reason code) Charge exceeds the allowed amount
• 2 (reason code) Patient's coinsurance share