What is one of the absolute essentials for HCC coding?

• A. Know ICD-10-CM and project guidelines
• B. Use CPT for diagnoses
• C. Only review bills
• D. Rely on secondhand summaries

Answer: (A)

Understanding ICD-10-CM diagnosis codes and the CMS-HCC guidelines is essential for HCC coding. HCCs are determined by specific diagnosed conditions, and the mapping from ICD-10-CM codes to CMS risk-adjustment categories depends on precise code definitions and guideline rules. Mastery of ICD-10-CM allows you to accurately identify the patient's conditions and select the appropriate codes, while the CMS-HCC guidelines explain which codes count toward which HCCs, how multiple conditions interact, sequencing considerations, and how documentation should support the codes. This combo is what ensures valid risk adjustment, compliant coding, and proper reimbursement.

CPT codes cover procedures and services, not diagnoses, so they cannot substitute for ICD-10-CM when identifying HCCs. Merely reviewing bills without examining the clinical documentation and the actual diagnoses fails to establish proper coding support. Relying on secondhand summaries or outdated materials is risky because guidelines and mappings can change; you need the primary ICD-10-CM codes and the official CMS-HCC guidance.