OA-23 Denial — How to Appeal for Behavioral Health
OA-23 (prior authorization required / other payer) 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
The payer is saying this service either required prior authorization that another payer should have provided, or that the prior authorization from another payer is needed before they will adjudicate. In behavioral health, OA-23 is commonly used to deny ongoing therapy when authorization from a primary insurer was not obtained first.
MHPAEA Mental Health Parity Argument
When OA-23 is used to require prior authorization for mental health therapy without a comparable requirement for medical/surgical outpatient services, it constitutes an NQTL under MHPAEA — the payer must demonstrate the authorization standard is applied equally to both benefit classifications. CAA 2021 § 203 entitles you to the written NQTL comparative analysis on request; that disclosure duty applies regardless of the 2025 federal non-enforcement of the 2024 Final Rule.
Request your payer's written Non-Quantitative Treatment Limitation (NQTL) comparative analysis. They are required to provide it under CAA 2021 § 203.
Appeal strategy for OA-23
Clarify with the payer exactly which authorization is missing — is it their own, or another payer's? If it is a coordination-of-benefits issue, submit the primary EOB. If the payer is requiring a prior authorization that they themselves should have issued, invoke MHPAEA: compare the authorization requirement to what is required for comparable medical/surgical services. Request the payer's NQTL analysis documenting why mental health therapy requires authorization while comparable outpatient medical services do not.
CPT codes commonly denied with OA-23
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What does OA-23 mean on a behavioral health claim?
The payer is saying this service either required prior authorization that another payer should have provided, or that the prior authorization from another payer is needed before they will adjudicate. In behavioral health, OA-23 is commonly used to deny ongoing therapy when authorization from a primary insurer was not obtained first.
How do I appeal a OA-23 denial?
Clarify with the payer exactly which authorization is missing — is it their own, or another payer's? If it is a coordination-of-benefits issue, submit the primary EOB. If the payer is requiring a prior authorization that they themselves should have issued, invoke MHPAEA: compare the authorization requirement to what is required for comparable medical/surgical services. Request the payer's NQTL analysis documenting why mental health therapy requires authorization while comparable outpatient medical services do not.
Does MHPAEA apply to OA-23 denials?
Yes. When OA-23 is used to require prior authorization for mental health therapy without a comparable requirement for medical/surgical outpatient services, it constitutes an NQTL under MHPAEA — the payer must demonstrate the authorization standard is applied equally to both benefit classifications. CAA 2021 § 203 entitles you to the written NQTL comparative analysis on request; that disclosure duty applies regardless of the 2025 federal non-enforcement of the 2024 Final Rule. Request the payer's written Non-Quantitative Treatment Limitation (NQTL) comparative analysis under CAA 2021 § 203 — that statutory disclosure duty applies regardless of the 2025 federal non-enforcement of the 2024 Final Rule.
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.