Definition · Value-based care

Hierarchical Condition Category (HCC)

A Hierarchical Condition Category (HCC) is a group of related diagnosis codes that CMS uses to predict a patient's future healthcare costs. Each HCC carries a weight, and within a disease family only the most severe category counts. HCCs feed the risk scores behind Medicare Advantage payments and ACO benchmarks. Payment year 2026 uses the V28 model.

What an HCC is

An HCC groups thousands of ICD-10 diagnosis codes into categories that predict cost. Diabetes with complications, congestive heart failure, and major depression each map to a category. The hierarchy means that if a patient has codes in two related categories, only the more severe one counts toward the score.

CMS has been moving from the V24 model to the 2024 CMS-HCC model, known as V28. V28 has 115 payment HCCs, up from 86 in V24. The phase-in started in 2024 at 33% V28. For payment year 2026, risk scores are 100% V28 with no blend, completing the three-year transition.

V28 regrouped many conditions and removed some codes that used to map to a payment HCC. Practices that built documentation habits around V24 should check their common diagnoses against the V28 mappings. In Rivvi, staff can upload a diagnosis or claims extract and ask which patients have chronic conditions but no visit this year.

Questions

HCCs, answered

What does HCC stand for in healthcare?

HCC stands for Hierarchical Condition Category. It is a group of clinically related diagnoses that CMS uses in its risk adjustment model. Each category carries a coefficient, and a patient's categories plus demographic factors add up to a risk adjustment factor (RAF) score.

What is the difference between HCC V24 and V28?

V28 is the 2024 CMS-HCC model that replaced V24 over three years. It has 115 payment HCCs compared with 86 in V24, regroups many conditions, and drops some diagnosis codes from payment categories. For payment year 2026, Medicare Advantage risk scores are calculated entirely on V28.

How often do HCCs need to be documented?

Every calendar year. An HCC only counts toward the risk score if a supporting diagnosis is documented in an eligible encounter during the year. Chronic conditions do not roll forward automatically, so patients with long-term conditions need at least one visit where those conditions are assessed and recorded.

Do HCCs affect ACOs or just Medicare Advantage?

Both. Medicare Advantage plans are paid on HCC-based risk scores. The Medicare Shared Savings Program and other ACO models also use CMS-HCC risk scores to adjust the spending benchmarks ACOs are measured against. Documentation therefore affects how much room an ACO has to earn shared savings.

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Hierarchical Condition Category (HCC)

What an HCC is

HCCs, answered

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