OA-23 Denial Code: Prior Payer Adjudication — What It Means

What Does OA-23 Mean?

OA-23 is the code that confuses new billers most — because it usually isn't a denial at all. On a secondary claim, OA-23 reports the amount the PRIMARY payer already handled (paid plus contractual adjustments), which the secondary payer is backing out before calculating its own payment. Seeing OA-23 on a correctly-paid secondary remittance is normal. The problems start when the numbers feeding it are wrong.

Code group: OA (Other Adjustment) — neither contractual obligation nor patient responsibility · Usually: informational, not actionable. Check the math before working it.

Why OA-23 Happens

Normal secondary adjudication — the primary's payment + adjustment being accounted for (not an error)
Primary payer information was reported incorrectly on the secondary claim
COB order is wrong — the "secondary" payer believes it's not secondary
The primary EOB/ERA data didn't transfer completely in the crossover
Duplicate primary payment data (claim sent both by crossover and manually)

How to Fix a OA-23 Denial

Step 1: First, do the math: primary paid + primary adjustments + secondary paid + patient responsibility should equal the billed amount. If it balances, OA-23 is informational — close it.
Step 2: If the secondary paid $0 unexpectedly, verify the primary payment data on the secondary claim matches the primary ERA exactly.
Step 3: Confirm COB order with both payers — many OA-23 confusions are really COB disputes (see CO-22).
Step 4: For Medicare crossover claims, verify the crossover actually occurred; resubmit with the primary remittance attached if it didn't.
Step 5: Correct and resubmit the secondary claim with complete primary adjudication data when fields were missing.

How to Prevent OA-23

Submit secondary claims electronically with full, field-accurate primary ERA data
Verify COB order during eligibility verification — before the first claim, not after
Reconcile secondary remittances against expected secondary liability, not just "payment received"
Let Medicare crossovers complete before manually submitting to the supplemental payer (prevents duplicates)

OA-23 Appeal Letter Template

“The secondary claim [number] processed with incorrect primary payer data. Attached is the primary payer's remittance advice showing paid amount [$x] and contractual adjustment [$y]. We request reprocessing using the correct primary adjudication amounts, with secondary liability calculated accordingly.”

Frequently Asked Questions

Is OA-23 a denial I need to work?

Usually no. It's the secondary payer accounting for what the primary already paid and adjusted. Work it only when the remittance math doesn't balance or the secondary payment is unexpectedly zero.

Why did the secondary pay nothing and show OA-23?

Often legitimate: if the primary's payment met or exceeded the secondary's allowed amount, the secondary owes nothing. But verify the primary data on the claim was accurate — wrong primary amounts produce wrong secondary math.

What's the difference between OA, CO, and PR prefixes?

CO = contractual obligation (practice absorbs), PR = patient responsibility (billable to patient), OA = other adjustment (neither — typically informational accounting like prior payer impact). The prefix decides who, if anyone, owes the amount.

How do Medicare crossover claims relate to OA-23?

When Medicare forwards claims to supplemental payers automatically, the supplement's remittance shows OA-23 for Medicare's payment and adjustment. That's the crossover working as designed.

OA-23 Denial Code: Impact of Prior Payer Adjudication