CARC 18 Denial Appeal
Exact duplicate claim
Exact duplicate claim/service.
Why CARC 18 hits behavioral-health claims
BH legitimately bills the same CPT code more than once on the same date for clinically distinct encounters (e.g., a morning therapy session and a separate evening crisis session, or two providers in a group); automated systems flag these as duplicates.
The winning argument
The services were clinically distinct, separate encounters at different times or by different rendering providers, properly identified with modifiers — not a duplicate.
- This was a corrected claim intended to replace the original, not duplicate it.
- The distinct encounters addressed separate clinical needs.
Public sources you can cite
Every argument traces to a verified public source — no invented citations.
Sample appeal letter body
Replace the {{placeholders}} with your own information before sending.
We are appealing the denial of {{cpt_code}} for {{patient_reference}} on {{dates_of_service}}, rejected under CARC 18 as an exact duplicate. This is not duplicate billing. The patient required two distinct behavioral-health encounters that day: the first for {{description_of_first_encounter}} at {{time_of_first_encounter}}, and a separate encounter for {{description_of_second_encounter}} at {{time_of_second_encounter}}. We appended modifier {{modifier_used}} to designate the second as a distinct procedural service. Please reprocess the second service line; the enclosed progress notes verify these were separate, medically necessary interventions.You'll need to supply: cpt_code, patient_reference, dates_of_service, description_of_first_encounter, time_of_first_encounter, description_of_second_encounter, time_of_second_encounter, modifier_used
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