Appealing a Humana CO-16 Denial
A Humana CO-16 denial (missing or incomplete information) 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 says your claim is missing information required to process it. You should receive a remark code (RARC) with this denial specifying exactly what is missing — look for an N-code or M-code on the same line of the RA.
Your appeal strategy
Identify the specific remark code that accompanies CO-16. Resubmit the claim with the missing element (NPI, taxonomy code, rendering provider, place of service, etc.). If the claim data was complete and the denial is in error, appeal with documentation proving each required field was present.
What Humana requires
P.O. Box 14601
Lexington, KY 40512
30 calendar days (Level-1 appeal)
60 days from Level-1 denial
1-800-832-4651
Humana administers behavioral health through an internal BH team. Strong Medicare Advantage presence — MA plans follow Medicare appeals rules (42 CFR § 422), which differ from commercial ERISA rules.
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Generate my appeal letter →Frequently asked questions
How long does Humana have to respond to a CO-16 appeal?
Under federal regulations and most state prompt-payment laws, Humana 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-16 denials?
CO-16 denials are not directly tied to mental health parity protections in most cases — this code is a general adjudication rule that applies equally to all claim types. MHPAEA may still be relevant if the underlying reason for the denial differs for mental health vs. medical/surgical services. When in doubt, include a parity argument in your appeal.
Can I appeal a CO-16 denial more than once?
Yes. Most payers, including Humana, 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-16 denial from Humana?
At minimum: the original Explanation of Benefits (EOB) or Remittance Advice (RA) showing the CO-16 denial, the original claim details (CPT code, date of service, NPI, charge amount), and any clinical documentation supporting medical necessity. Submit everything in one packet with a cover letter citing the specific denial code, the date of service, and the claim number.