- OA 23 denials occur when secondary payers cannot process claims correctly because of coordination of benefits issues.
- Common causes include incorrect payer sequencing, missing EOB details, duplicate submissions, and outdated patient insurance information.
- Billing teams must correct and resubmit affected claims properly to prevent avoidable write-offs, repeated denial rework, and recurring COB-related issues.
Most billing teams know this feeling. A claim goes out clean. It comes back stamped OA 23. No missing field they can immediately point to, no obvious error staring back at them. Just a short code indicating the prior payer’s adjudication impacted this claim, and now the whole thing needs rework.
What makes OA 23 genuinely frustrating isn’t any single instance. It’s the repetition. These denials tend to cluster. Once the first one lands, more follow, usually from the same payer or the same category of patients. That pattern is the signal worth paying attention to.
What Is OA 23 Denial Code and What Does It Actually Mean
The “OA” stands for “Other Adjustment,” a Claim Adjustment Group Code that operates under the X12 CARC (Claim Adjustment Reason Code) framework maintained by the Washington Publishing Company. Reason code 23 specifically signals that a prior payer’s adjudication, including their payments, denials, and contractual adjustments, directly affected the current claim.
When a patient carries two insurance plans, the secondary payer won’t process its portion until it knows exactly what the primary payer already paid, denied, or wrote off. If that information arrives incomplete, missing, or without a proper Explanation of Benefits attached, the secondary payer issues OA 23. Sometimes it surfaces as a payment adjustment, not a hard denial. Either way, the billing team needs to act on it.
Worth noting: OA 23 doesn’t fall under patient responsibility or contractual write-off groups. It sits specifically in the “Other Adjustment” category, which points back to coordination gaps rather than coverage limits.
Why Does OA 23 Keep Showing Up Across Claims
Recurring OA 23 denials rarely result from a one-time billing mistake. They usually reflect a structural problem, either in how the practice collects insurance data at registration or how its Coordination of Benefits workflow runs downstream. The CMS COB program exists to ensure claims are paid correctly by identifying health benefits available and coordinating the payment process between payers. When a practice’s internal processes don’t align with that structure, OA 23 follows reliably.
The most common root causes include:
Incorrect payer sequencing: Billing to the secondary before the primary adjudicates, or listing insurers in the wrong order, generates OA 23 almost predictably.
Missing or incomplete EOB: The secondary payer needs the full Explanation of Benefits from the primary, including payment amounts, contractual adjustments, and denial reasons, before it can calculate its portion.
Primary payer errors: Miscalculations or system glitches on the primary side produce adjudications that secondary payers flag. Billing teams often don’t catch this until the denial lands.
Non-covered services carried forward: When the primary denies a service as non-covered and the secondary claim doesn’t document that determination clearly, OA 23 can follow.
Outdated patient coverage details: Policy terminations, mid-year plan changes, or lapses the front desk missed during registration create downstream COB failures weeks later.
Duplicate claim submissions: Two submissions for the same date of service hit the payer simultaneously. Payers catch this and respond with OA 23 or related adjustment codes.
Timely filing violations: Filing outside the secondary payer’s deadline removes the practice’s reimbursement window entirely.
The deeper pattern here is that most of these problems originate at registration or eligibility verification, well before the claim ever leaves the practice.
How OA 23 Differs from CO-22 and PR-1
How OA 23 Silently Damages Revenue Cycle Performance
The financial toll builds faster than most revenue cycle leaders realize. According to AHIMA’s journal, nearly 20% of all claims are denied, and as many as 60% of returned claims are never resubmitted. That second figure is the one that should concern anyone managing a billing operation. Claims that never get corrected and resubmitted don’t disappear cleanly. They become permanent write-offs.
The American Hospital Association reports that hospitals and health systems spent an estimated $19.7 billion in 2022 trying to overturn denied claims, with nearly 15% of all claims submitted to private payers initially denied. On a rework basis, resolving a denial costs practices around $25 per claim and hospitals approximately $181 per claim. Neither number is trivial when multiplied across months of recurring OA 23 volume.
Beyond the dollar amounts, there is a staffing cost that rarely gets measured directly. Billing staff spend real hours reconstructing COB data, calling patients to confirm dual coverage status, and rebuilding claims that should have gone out correctly the first time.
When Does COB Confusion Most Likely Trigger an OA 23 Denial
COB-related OA 23 denials tend to cluster around specific clinical and administrative situations. Patients carrying Medicare alongside a secondary commercial plan generate a notable share, particularly when Medicare’s remittance data doesn’t transfer cleanly through the COBA coordination pathway to the secondary payer.
New enrollments and mid-year plan changes create a concentrated vulnerability window. A patient updates their insurance, but the practice management system doesn’t reflect the change before the next visit. A claim goes out with outdated primary payer data. OA 23 arrives a few weeks later.
Workers’ compensation and auto accident cases add another layer entirely. When liability insurers and group health plans share responsibility for the same episode of care, COB rules between them aren’t always applied uniformly across payers. That inconsistency creates room for OA 23 even when the billing team did everything correctly on their end.
How to Fix an OA 23 Denial Before It Becomes a Write-Off
Start by pulling the primary payer’s remittance advice. The billing team needs the exact payment amount, any contractual adjustments, and the denial reason if the primary denied rather than paid. That data drives everything that follows.
The resubmission then needs clean COB fields: primary payer name, policy number, payment amount, and the date of primary adjudication. Most secondary payers accept electronic resubmission with updated claim loops. Some still require paper appeals with the primary EOB physically attached.
Concrete resolution steps:
Retrieve the primary payer’s EOB or Electronic Remittance Advice (ERA) for the specific claim in question
Confirm that payer sequencing aligns with the actual coordination order on file for that patient
Correct any coding discrepancies that contributed to the primary denial in the first place
Resubmit within the secondary payer’s appeal or resubmission deadline, not the original filing window
Document the resolution clearly in the billing system to track denial patterns over time
If the primary payer made an error, the practice needs to file a corrected claim with the primary first, wait for updated adjudication, then resubmit to the secondary with the corrected EOB. Skipping that step and going directly to the secondary is one of the more reliable ways OA 23 resurfaces on the same claim.
How AI Help RCM Teams Reduce OA 23 Denial Rates
Manual review struggles to catch COB errors consistently at scale. Most billing teams process hundreds of claims daily, and the points where OA 23 slips through, registration, eligibility verification, COB sequencing, and claim scrubbing, are exactly where human review becomes inconsistent under volume pressure.
AI agents built for revenue cycle management handle many of these validation tasks in real time, before the claim reaches the clearinghouse rather than after it returns denied. That upstream shift makes a meaningful difference in first-pass resolution rates.
Specifically, AI agents contribute to OA 23 prevention by:
Running real-time eligibility checks that detect dual coverage and confirm COB order at registration
Verifying primary payer adjudication status before secondary claim generation
Cross-referencing prior EOBs to populate accurate COB fields in claim data
Monitoring claim age against payer-specific timely filing deadlines to prevent unnecessary write-offs
Surfacing denial pattern trends so billing teams can identify which payers or service lines generate recurring OA 23 denials
The AHA’s 2024 analysis found that 62% of prior authorization denials and 50% of initial claim denials that were appealed ultimately got overturned. That’s a strong recovery rate. Yet it also reflects how many of those denials were preventable to begin with. Getting upstream of the denial rather than chasing it downstream is where AI agents deliver their clearest value.
Why Droidal Stands Out in OA 23 Denial Prevention
For practices that want to move beyond reactive denial management, working with a team that understands the precise failure points in COB workflows matters considerably. Droidal brings deep expertise in revenue cycle management and AI-driven claim intelligence to exactly this problem.
Rather than treating OA 23 denials as isolated billing errors, Our AI Agents identifies the systemic gaps at registration and eligibility stages where most COB issues start and monitor claim data continuously, flag COB inconsistencies before submission, and support billing teams with denial resolution workflows that cut the time between denial receipt and clean resubmission.
Ready to stop treating OA 23 denials as isolated billing errors? Book a demo with Droidal and see how our AI Agents identify COB gaps at the source, flag coordination of benefits inconsistencies before claims go out, and accelerate your team’s path from denial receipt to clean resubmission so revenue cycle disruptions stop compounding before they start.
CLEAR OA-23 CLAIM ISSUES FASTER
Denials Management AI traces prior-payer adjustments and routes the next action.
