Appealing an Aetna CO-119 Denial
An Aetna CO-119 denial (benefit maximum reached) 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 the patient has hit the maximum number of visits, days, or dollar amount allowed for this benefit under their plan. For mental health services, benefit maximums are frequently the most direct form of MHPAEA parity violation.
MHPAEA Mental Health Parity Argument
MHPAEA (29 CFR § 2590.712(c)) prohibits visit, day, or dollar limits on mental health or SUD benefits that are more restrictive than those applied to medical/surgical benefits — if a plan covers unlimited outpatient medical visits but caps therapy at 30 sessions, that is a per-se parity violation. CAA 2021 § 203 separately requires the plan to produce a written comparative analysis; that statutory duty was unaffected by 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
Determine whether the patient's plan imposes a visit or day limit on mental health services that does not apply to comparable medical/surgical outpatient services. If the limit is more restrictive for mental health, this is a textbook MHPAEA violation. Request the payer's comparative analysis document for mental health vs. medical/surgical benefit limitations.
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 CO-119 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 CO-119 denials?
Yes. MHPAEA (29 CFR § 2590.712(c)) prohibits visit, day, or dollar limits on mental health or SUD benefits that are more restrictive than those applied to medical/surgical benefits — if a plan covers unlimited outpatient medical visits but caps therapy at 30 sessions, that is a per-se parity violation. CAA 2021 § 203 separately requires the plan to produce a written comparative analysis; that statutory duty was unaffected by the 2025 federal non-enforcement of the 2024 Final Rule. When filing a CO-119 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 CO-119 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 CO-119 denial from Aetna?
At minimum: the original Explanation of Benefits (EOB) or Remittance Advice (RA) showing the CO-119 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.