HCC most commonly stands for Hierarchical Condition Category, a system used in medical coding and risk adjustment to group certain diagnoses based on their expected impact on healthcare costs. The HCC in medical terms can also refer to hepatocellular carcinoma, a type of primary liver cancer.
If you’re looking for “What Does HCC Mean In Medical Terms”, the answer depends on the context. In medical billing, HCC refers to Hierarchical Condition Category, while clinical settings may use it to refer to liver cancer. Documented diagnoses can affect a patient’s risk adjustment factor (RAF) score, which helps determine risk-adjusted payments.
This guide explains how HCC coding works, how RAF scores relate to HCCs, why accurate clinical documentation matters, and what to know about the CMS-HCC model updates.
HCC carries two different meanings depending on where you read it. In medical billing and coding, HCC means Hierarchical Condition Category. In an oncology or clinical setting, HCC usually means hepatocellular carcinoma, a type of liver cancer unrelated to insurance coding.
This guide focuses on the billing and risk-adjustment meaning of HCC, including how HCC coding affects RAF scores, reimbursement, and clinical documentation.
HCC coding is the process of grouping a patient’s ICD-10-CM diagnoses into categories that reflect how clinically complex that patient is. CMS uses those categories to predict future healthcare costs and calculate reimbursement.
CMS introduced this model in 2004 to solve a real problem. Health plans were getting paid roughly the same amount for every patient, whether that patient was healthy or managing five chronic conditions at once. HCC coding ties payment to actual patient complexity instead of a flat average.
It is called hierarchical because related diagnoses in the same disease family are ranked by severity, and only the most severe one counts toward the risk score. A milder version of the same condition does not stack on top of the more severe one.
Take diabetes as an example. If a patient is coded for both diabetes without complications and diabetes with a chronic complication in the same year, only the more severe code counts toward the risk score. The milder code gets dropped.
This prevents a health plan from getting credit twice for what is really one underlying condition, coded at two different levels of detail.
An ICD-10-CM code identifies a specific diagnosis, such as type 2 diabetes with a documented kidney complication. An HCC groups certain ICD-10-CM diagnosis codes into broader risk categories that are used in risk-adjustment models to reflect a patient’s expected healthcare costs.
ICD-10-CM | HCC |
Identifies a specific diagnosis | Groups certain diagnoses into a risk category |
Used to report diagnoses on healthcare claims and other records | Used within risk-adjustment models to calculate a patient’s risk |
Contains tens of thousands of diagnosis codes | Contains a much smaller set of condition categories |
A diagnosis code may be reported when clinically supported | An HCC is assigned when an eligible diagnosis maps to that model’s HCC category |
In simple terms: ICD-10-CM tells you what condition the patient has, while an HCC groups certain conditions to help determine how medically complex the patient is for risk-adjustment purposes.
HCC coding helps risk-adjustment models account for the medical conditions documented in a patient’s record and the healthcare costs those conditions may predict. In applicable CMS risk-adjustment models, documented diagnoses are mapped to HCCs, and the resulting risk factors are combined with demographic and other model-specific factors to calculate a patient’s risk score.
In general, a higher risk score indicates greater expected healthcare needs compared with the population used to establish the model. Health plans use these risk-adjusted calculations to account for differences in the health status of their members when determining payments.
For example, a patient’s documented diabetes may map differently depending on whether the medical record supports a condition without complications or a more serious form with a documented complication. The applicable HCC and its coefficient depend on the risk-adjustment model and year being used.
This is why accurate documentation and coding matter. If a clinically supported condition is missing, incomplete, or incorrectly coded, the patient’s health status may not be fully reflected in the applicable risk-adjustment model.
CMS-HCC V28 reached full implementation in 2026, completing the three-year phase-in of the 2024 CMS-HCC risk-adjustment model. The transition changed how diagnoses are classified and which ICD-10-CM codes map to payment HCCs.
What Changed | 2020 CMS-HCC Model (V24) | 2024 CMS-HCC Model (V28) |
Payment HCCs | 86 | 115 |
ICD-10-CM codes mapped to payment HCCs | 9,797 | 7,770 |
Classification | 2020 HCC structure | Reclassified using ICD-10-based clinical categories |
Implementation | Previous model | Fully phased in for 2026 |
V24-to-V28 Phase-In
Calendar Year | V24 | V28 |
2024 | 67% | 33% |
2025 | 33% | 67% |
2026 | 0% | 100% |
A diagnosis code that is mapped to a payment HCC under V24 does not necessarily map to a payment HCC under V28. CMS reports that 2,236 ICD-10-CM codes that were mapped to payment HCCs under the 2020 model were no longer mapped to payment HCCs under the 2024 model. More than 95% of those codes were moved as part of the transition to an ICD-10-based HCC classification rather than simply removed from the HCC classification.
HCC models group certain ICD-10-CM diagnoses into risk categories based on their expected impact on healthcare costs. The specific diagnoses that map to an HCC depend on the risk-adjustment model and version being used, so the same clinical condition may not have the same HCC treatment across models.
Condition | What Coders Need to Verify |
Diabetes | The type of diabetes and any documented complications or associated conditions |
Heart failure | The specific type and severity of heart failure documented by the provider |
COPD | Whether COPD is documented and supported by the clinical record |
Cancer | The specific type, status, and other details required by the applicable coding and risk-adjustment rules |
Depressive or bipolar disorders | The specific diagnosis, severity, and other clinically relevant details documented |
Chronic kidney disease | The documented CKD stage and supporting clinical information |
The key point is specificity. A diagnosis must be documented clearly enough for the coder to assign the appropriate ICD-10-CM code, and that code must be eligible for the applicable risk-adjustment model. Simply having a condition mentioned somewhere in the chart does not automatically create an HCC.
In cardiology, certain documented cardiovascular conditions may map to HCCs under an applicable risk-adjustment model. Heart failure and some cardiomyopathies, for example, may fall into risk-adjustment categories depending on the specific diagnosis and model.
The important distinction is that the clinical diagnosis comes first. The provider documents the patient’s condition, the coder assigns the appropriate ICD-10-CM code, and the applicable risk-adjustment model determines whether that code maps to an HCC.
This also means coders should not assume that every cardiac diagnosis automatically creates an HCC. The diagnosis, documentation, ICD-10-CM code, and applicable model all matter.
CMS-HCC and HHS-HCC are separate risk-adjustment models used in different healthcare programs. CMS-HCC is used for Medicare Advantage risk adjustment, while HHS-HCC is used in the Affordable Care Act’s individual, small-group, and merged markets. Because the models serve different programs, their diagnosis mappings, model factors, and data-submission requirements can differ.
CMS-HCC | HHS-HCC |
Used for Medicare Advantage risk adjustment | Used for ACA individual and small-group market risk adjustment |
Applies to Medicare Advantage plan risk scores | Supports risk adjustment among participating health insurance issuers |
Uses CMS’s Medicare risk-adjustment models and mappings | Uses HHS-developed risk-adjustment models and mappings |
Has its own rules for which diagnoses and services are eligible for risk adjustment | Has separate diagnosis-filtering and service-eligibility requirements |
Both have separate rules, so practices should verify the requirements that apply to each program rather than treating them interchangeably.
Documentation is what supports the diagnosis code used for HCC risk adjustment, not the diagnosis label alone. A condition sitting in a patient’s history or problem list does not automatically qualify for risk adjustment. The medical record must provide enough clinical detail for a coder to assign the appropriate ICD-10-CM code under the applicable guidelines.
The basic rule is simple: a coder can only report what the medical record supports.
A few things to look for in the documentation include:
Accurate, well-supported documentation gives coders the clarity they need to report HCC-related diagnoses correctly.
HCC can mean different things in medicine, but in medical billing and risk adjustment, it refers to Hierarchical Condition Category. The applicable model determines how documented diagnoses are classified and used in risk-adjustment calculations.
Accurate ICD-10-CM coding and clear clinical documentation help ensure that a patient’s documented health conditions are represented appropriately. Proper knowledge of HCC rules also helps coding teams avoid unsupported diagnoses, missed conditions, and outdated assumptions about risk adjustment.
HCC-related diagnoses generally need to be supported during the applicable reporting period. A diagnosis from a previous year should not simply be carried forward without current clinical support.
No. Only certain ICD-10-CM diagnosis codes map to HCC categories under a specific risk-adjustment model. The mapping can also change between model versions, such as V24 and V28.
Yes. A patient can have multiple HCCs when different documented conditions map to separate eligible categories. However, hierarchical relationships within a disease group can affect which categories are ultimately included in the risk score.
No. Having a chronic condition does not automatically mean it qualifies for an HCC. The diagnosis must meet the requirements of the applicable risk-adjustment model and map to an eligible HCC category.
Yes. CMS can update HCC models, diagnosis mappings, coefficients, and other risk-adjustment requirements. V28, for example, changed the HCC structure and diagnosis mappings compared with V24.
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