What does HCC mean in medical coding?
HCC stands for Hierarchical Condition Category. HCCs are groupings used in certain risk adjustment models to help account for differences in expected healthcare needs and costs among patients.
Coders do not assign an “HCC code” directly from the medical record. The coder assigns the appropriate ICD-10-CM diagnosis code. Depending on the risk adjustment model and model year, that diagnosis may map to an HCC.
Not every ICD-10-CM diagnosis maps to an HCC, and mappings can change as models are updated. CMS publishes model software and ICD-10-CM mappings for Medicare Advantage risk adjustment.
Why are HCCs used?
Risk adjustment is designed to account for differences in patient health status. A patient with multiple serious chronic conditions may reasonably be expected to require more healthcare resources than a patient with few or no significant conditions.
In Medicare Advantage, the CMS-HCC model uses demographic information and diagnoses to help calculate risk scores used in payment methodology. Other risk adjustment models also exist, which is why a coder should never assume that one HCC mapping applies to every payer or program.
For calendar year 2026, CMS completed the phase-in of the 2024 CMS-HCC model for non-PACE Medicare Advantage organizations. CMS states that 100% of those Part C risk scores are calculated using the 2024 CMS-HCC model in 2026.
How does HCC coding work?
Start with the medical record. Identify conditions that are documented and supported for the encounter under applicable coding and reporting rules.
Use the Alphabetic Index, Tabular List, conventions, instructional notes, specificity, and Official Guidelines to select the correct diagnosis code.
If the diagnosis is eligible under the applicable risk adjustment model, the ICD-10-CM code may map to an HCC used in risk-score calculations.
The order matters. Strong HCC coding begins with accurate diagnosis coding and supported documentation—not with searching for a category that affects a risk score.
Why is it called “hierarchical”?
Within some disease groupings, related condition categories are arranged in a hierarchy. When a patient has diagnoses that map to multiple related categories in the same hierarchy, the model may recognize the more severe category rather than adding the full effect of every related category.
This helps prevent closely related manifestations or severity levels from being counted as though they represented completely separate disease burdens.
Why documentation matters so much in HCC coding
Risk adjustment coding is documentation-driven. A condition should not be reported merely because it appeared on an old problem list, was coded last year, or could increase a risk score.
Learn how coders distinguish supported from unsupported diagnoses →
Learn how CMS validates diagnoses through RADV audits →
Learn how the MEAT framework can help with documentation review →
The medical record must support the diagnosis according to the rules that apply to the encounter, provider type, setting, and risk adjustment program. Coders should evaluate clinical documentation, specificity, status of the condition, assessment and plan, and other relevant information.
Many chronic conditions may need to be documented again during the applicable reporting or data-collection period to affect a current risk score. That does not mean a coder should automatically “recapture” a diagnosis. The current record must support appropriate reporting.
Accurate coding works both ways
Missing a supported diagnosis can result in an incomplete picture of the patient’s health status. Reporting an unsupported diagnosis can create significant compliance and audit risk. The goal is neither undercoding nor overcoding—it is accurate, defensible coding.
What is a RAF score?
RAF commonly refers to a Risk Adjustment Factor. In models such as CMS-HCC, the risk score reflects a combination of demographic and disease-related factors. HCCs associated with qualifying diagnoses may contribute to the disease component of that score.
A higher risk score generally represents a population expected to have greater healthcare costs under the model. But the coder’s job is not to maximize the RAF score. The coder’s job is to report diagnoses accurately based on the documentation and applicable rules.
What does an HCC or risk adjustment coder do?
Depending on the employer and workflow, an HCC coder may review medical records, validate diagnosis codes, identify documentation gaps, evaluate chronic-condition documentation, perform prospective or retrospective reviews, participate in coding quality audits, and support provider education.
Strong HCC coders need more than a list of diagnoses that map to categories. They need working knowledge of ICD-10-CM, anatomy, medical terminology, pathophysiology, documentation, risk adjustment models, and compliance.
| Weak approach | Strong approach |
|---|---|
| Start with a list of HCC diagnoses and look for them in charts. | Start with the medical record and determine what diagnoses are actually supported. |
| Assume a chronic condition carries forward automatically. | Evaluate current documentation and applicable reporting rules. |
| Choose a code based on its risk value. | Choose the most accurate ICD-10-CM code supported by the documentation. |
| Focus only on “capturing HCCs.” | Focus on coding accuracy, documentation integrity, and compliance. |
How does HCC coding relate to the CRC certification?
AAPC’s Certified Risk Adjustment Coder (CRC) credential is specifically focused on risk adjustment coding. Its study materials cover ICD-10-CM coding and documentation, risk adjustment models, predictive modeling, quality of care, the relationship between risk adjustment and medical funding, clinical documentation barriers, and frequently coded conditions in risk adjustment models.
If you want to specialize in HCC and risk adjustment coding, the CRC is the credential most directly aligned with that specialty.
You do not need to earn a CPC before pursuing the CRC. AAPC currently identifies the CRC as a stand-alone certification.
Read: What Is a Certified Risk Adjustment Coder? →
Read: CRC vs CPC — Which Certification Is Right for You? →
HCC Coding FAQ
Does every diagnosis have an HCC?
No. Only selected ICD-10-CM codes map to HCCs under a specific risk adjustment model. Mapping can also change by model and year.
Is HCC coding only for Medicare Advantage?
No. HCC-style risk adjustment concepts are used in more than one healthcare program and model. Medicare Advantage and the CMS-HCC model are among the most commonly discussed examples.
Is HCC coding just chronic-condition coding?
Chronic conditions are an important part of risk adjustment, but HCC coding requires broader knowledge of ICD-10-CM, documentation, model rules, clinical concepts, and compliance.
Do all chronic conditions need to be coded every year?
Do not use that as a blanket rule. Risk adjustment models use diagnosis data from defined reporting periods, and current documentation must support reportable diagnoses. Always apply the rules for the specific model, payer, setting, and encounter.
Do I need the CRC to become an HCC coder?
Employer requirements vary. The CRC demonstrates specialized risk adjustment knowledge, but each employer decides what certification, education, and experience it requires.
Want to learn HCC and risk adjustment coding?
MediCode Bootcamp offers CRC education that goes beyond memorizing HCCs. Learn ICD-10-CM application, documentation supportability, risk adjustment concepts, compliance, and case-based coding with instructor support.
Explore the Self-Paced CRC CourseView CRC Boot CampFree CRC ResourcesSources reviewed October 2026: CMS 2026 Model Software/ICD-10 Mappings; CMS 2026 Medicare Advantage Rate Announcement; AAPC CRC Study Guide; AAPC Risk Adjustment Search Tool. Model rules and mappings can change; always use current official resources.