Appealing an Aetna OA-23 Denial
An Aetna OA-23 denial (prior authorization required / other payer) is one of the most common claim rejections behavioral health therapists face. This guide explains exactly what caused the denial and the most effective appeal strategy for behavioral health practices.
What this denial 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 Aetna's written Non-Quantitative Treatment Limitation (NQTL) comparative analysis. They are required to provide it under the MHPAEA Enforcement Final Rule (2024).
Your appeal strategy
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.
What Aetna requires
P.O. Box 14463
Lexington, KY 40512
30 calendar days (Level-1 appeal)
60 days from Level-1 denial
1-860-754-2985
Aetna publishes MHPAEA comparative analyses on request; behavioral health benefits are administered through Aetna Behavioral Health. Document parity violation in detail — Aetna's internal process requires a specific MHPAEA flag in the appeal routing system.
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Generate my appeal letter →Frequently asked questions
How long does Aetna have to respond to a OA-23 appeal?
Under federal regulations and most state prompt-payment laws, Aetna must respond to a Level-1 internal appeal within 30 calendar days. If you receive an adverse determination, you typically have 60 calendar days from the date of the Level-1 denial to request external review. Send the appeal via certified mail or through the payer's portal and keep documentation of the submission date.
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. When filing a OA-23 appeal against Aetna, request their written comparative analysis for mental health vs. medical/surgical benefits under 29 CFR § 2590.712. Aetna publishes MHPAEA comparative analyses on request; behavioral health benefits are administered through Aetna Behavioral Health. Document parity violation in detail — Aetna's internal process requires a specific MHPAEA flag in the appeal routing system.
Can I appeal a OA-23 denial more than once?
Yes. Most payers, including Aetna, allow at least two levels of internal appeal (Level-1 and Level-2 or "expedited" review). After exhausting internal appeals, you have the right to request an Independent Medical Review (IMR) or external review through your state insurance commissioner. Keep copies of every appeal, submission confirmation, and payer response.
What documentation do I need to appeal a OA-23 denial from Aetna?
At minimum: the original Explanation of Benefits (EOB) or Remittance Advice (RA) showing the OA-23 denial, the original claim details (CPT code, date of service, NPI, charge amount), and any clinical documentation supporting medical necessity. Because this code has parity implications, also include a written request for Aetna's NQTL comparative analysis under MHPAEA. Submit everything in one packet with a cover letter citing the specific denial code, the date of service, and the claim number.