Appealing a Tricare CO-18 Denial
A Tricare CO-18 denial (duplicate claim) 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 believes this claim has already been submitted and paid (or denied). This can happen when a clearinghouse resubmits, when two claims share the same date, CPT code, and provider, or when the payer's system flags a resubmission as a duplicate.
Your appeal strategy
Pull the original claim and the RA for any prior payment or denial. If the original was paid, provide the remittance showing payment to close the loop. If the original was denied and you are legitimately resubmitting, include the original claim number and the RA for the denial to demonstrate this is a corrected resubmission, not a duplicate.
What Tricare requires
P.O. Box 7933
Madison, WI 53707
60 calendar days (Level-1 appeal)
90 days from Level-1 denial
Tricare is a federal program (10 U.S.C. § 1071 et seq.); state insurance law does not apply. Tricare administers its own mental-health and SUD benefit rules under 32 CFR Part 199 and its own appeal process — do not rely on the commercial MHPAEA framework (29 CFR § 2590.712). Verify the current benefit rule and appeal deadline with the regional contractor (Humana Military East / TriWest West) before filing.
Generate your Tricare CO-18 appeal letter
Therapists get 5 free letters every month. Appealing your own denial? It's $19 per letter, one-time, no subscription. No credit card needed to start.
Generate my appeal letter →Frequently asked questions
How long does Tricare have to respond to a CO-18 appeal?
Under federal regulations, Tricare must respond to a Level-1 internal appeal within 60 calendar days. State insurance law, including your state's prompt-payment statute, does not apply to this federal program — confirm the current response-window rules directly with the program administrator before filing. If you receive an adverse determination, you typically have 90 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-18 denials?
No. Tricare is not subject to the federal Mental Health Parity and Addiction Equity Act (MHPAEA) at all, so a parity argument does not apply to a CO-18 denial — or any denial — from this payer. Base your appeal on Tricare's own coverage rules and appeal process. Tricare is a federal program (10 U.S.C. § 1071 et seq.); state insurance law does not apply. Tricare administers its own mental-health and SUD benefit rules under 32 CFR Part 199 and its own appeal process — do not rely on the commercial MHPAEA framework (29 CFR § 2590.712). Verify the current benefit rule and appeal deadline with the regional contractor (Humana Military East / TriWest West) before filing.
Can I appeal a CO-18 denial more than once?
Yes. Most payers, including Tricare, allow at least two levels of internal appeal (Level-1 and Level-2 or "expedited" review). Keep copies of every appeal, submission confirmation, and payer response. After exhausting the regional contractor's internal reconsideration, TRICARE appeals escalate to the Defense Health Agency under 32 CFR 199.10. Your state insurance commissioner has no authority over TRICARE — it is a federal program administered by the Department of Defense.
What documentation do I need to appeal a CO-18 denial from Tricare?
At minimum: the original Explanation of Benefits (EOB) or Remittance Advice (RA) showing the CO-18 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.