HCC (Hierarchical Condition Category)

CMS risk-adjustment categories used to predict cost for Medicare Advantage and ACA marketplace populations. CMS-HCC v28 (current 2026 version) includes 115 categories built from 11,346 ICD-10-CM codes. Each HCC has a coefficient that contributes to the patient Risk Adjustment Factor (RAF). Captured HCC diagnoses must be documented and treated annually to count for risk score. Missed HCC capture is the largest revenue leak in Medicare Advantage practices.