Appealing a Tricare CO-4 Denial
A Tricare CO-4 denial (modifier inconsistent with procedure) 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 the modifier you used does not match the procedure code you billed. The most common trigger in behavioral health is omitting or misapplying the -25 modifier when billing an E/M visit on the same day as psychotherapy.
Your appeal strategy
Confirm which modifier triggered the denial via the Remittance Advice (RA). If the modifier is correct per CMS/CPT rules, cite the specific CPT guidelines and the payer's published billing policy and request re-adjudication. If the modifier was missing or incorrect, submit a corrected claim rather than an appeal.
What Tricare requires
P.O. Box 7933
Madison, WI 53707
60 calendar days (Level-1 appeal)
90 days from Level-1 denial
Tricare is federal (10 U.S.C. § 1071+) — state insurance law does not apply. MHPAEA does apply under 10 U.S.C. § 1089a (Mental Health Parity for Military). Managed by Humana Military (East) and Health Net Federal Services / TriWest (West). Regional contractor determines specific addresses and portals.
Generate your Tricare CO-4 appeal letter
First 5 letters free. No credit card. Editable draft in about 60 seconds.
Generate my appeal letter →Frequently asked questions
How long does Tricare have to respond to a CO-4 appeal?
Under federal regulations and most state prompt-payment laws, Tricare must respond to a Level-1 internal appeal within 60 calendar days. 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-4 denials?
CO-4 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-4 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). 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-4 denial from Tricare?
At minimum: the original Explanation of Benefits (EOB) or Remittance Advice (RA) showing the CO-4 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.