OA-23 Denial — How to Appeal for Behavioral Health
OA-23 (prior payer adjustment (coordination of benefits)) is one of the most common insurance denial codes behavioral health therapists encounter. This guide explains what triggered the denial and the most effective appeal strategy across all major payers.
What OA-23 means
This is a coordination-of-benefits code, not a prior-authorization denial. It means the client has more than one insurance plan, and this payer reduced or adjusted the payment based on what the primary payer already paid or adjusted. It shows up when the payer is the secondary plan on a claim, not when they are questioning whether authorization was obtained.
Appeal strategy for OA-23
Request the payer's coordination-of-benefits breakdown showing exactly how the primary payer's EOB or adjustment was applied to this claim. If the client has no other coverage on file, or the COB calculation looks wrong, submit the primary payer's EOB and dispute the specific numbers with the payer.
CPT codes commonly denied with OA-23
Appeal OA-23 by payer
Select your payer for appeal address, deadline, and payer-specific MHPAEA notes.
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Generate my appeal letter →Frequently asked questions about OA-23
What does OA-23 mean on a behavioral health claim?
This is a coordination-of-benefits code, not a prior-authorization denial. It means the client has more than one insurance plan, and this payer reduced or adjusted the payment based on what the primary payer already paid or adjusted. It shows up when the payer is the secondary plan on a claim, not when they are questioning whether authorization was obtained.
How do I appeal a OA-23 denial?
Request the payer's coordination-of-benefits breakdown showing exactly how the primary payer's EOB or adjustment was applied to this claim. If the client has no other coverage on file, or the COB calculation looks wrong, submit the primary payer's EOB and dispute the specific numbers with the payer.
Does MHPAEA apply to OA-23 denials?
OA-23 is a general adjudication code that typically applies equally to all claim types. MHPAEA may still be relevant if the payer applies the underlying rule differently to mental health services than to comparable medical/surgical services.
Which insurers most commonly issue a OA-23 denial?
All major commercial payers — Aetna, Cigna, Anthem, UnitedHealthcare, Humana, and BCBS plans — use OA-23. Government programs (Medicare, Medicaid, TRICARE) also issue this code. The appeal strategy is similar across payers, but deadlines and submission addresses vary. Select your payer from the list below for payer-specific instructions.