- CalOptima
- Capital District Physicians Health Plan
- Capital Health Plan
- CareFirst BlueChoice, Inc. of DC
- CareFirst BlueChoice, Inc. of MD
- CareFirst BlueChoice, Inc. of VA
- CareFirst of DC
- CareFirst of MD
- Caremore
- CareOregeon
- CareSource Georgia
- CareSource Indiana of IN
- CareSource Indiana of KY
- CareSource Indiana of WV
- CareSource Kentucky
- Careworks
- Cenpatico
- Central California Alliance for Health
- CHRISTUS Health Plan of LA
- CHRISTUS Health Plan of NM
- CHRISTUS Health Plan of TX
- Cigna of AK
- Cigna of AL
- Cigna of AZ
- Cigna of CA
- Cigna of CO
- Cigna of CT
- Cigna of DC
- Cigna of FL
- Cigna of GA