What Is HCC Coding? A Complete Guide for 2026

What Is HCC Coding?

Hierarchical Condition Category (HCC) coding is a risk adjustment methodology used by the Centers for Medicare and Medicaid Services (CMS) to predict future healthcare costs for patients. Medical coders play a critical role in this process by ensuring that every diagnosis is accurately captured using ICD-10-CM codes, which then map to specific HCC categories.

Why HCC Coding Matters

HCC coding directly impacts how much Medicare Advantage plans are reimbursed for each patient. When a patient's chronic conditions are accurately documented and coded, the plan receives appropriate funding to cover that patient's expected healthcare needs.

Key reasons HCC coding is essential:

• Accurate reimbursement, Plans receive funding that matches the true health burden of their population
• Quality of care, Complete documentation ensures care teams understand each patient's full clinical picture
• Regulatory compliance, CMS audits require that every coded condition is supported by clinical documentation
• RAF score accuracy, The Risk Adjustment Factor score determines per-member-per-month payments

How ICD-10-CM Codes Map to HCCs

Not every ICD-10-CM code maps to an HCC. Of the approximately 74,000 ICD-10-CM codes, only a subset are HCC-relevant. The mapping process works as follows:

1. Provider documents a condition during a face-to-face encounter

2. Coder assigns the most specific ICD-10-CM code supported by documentation

3. The code is crosswalked to the CMS-HCC model (V24 or V28)

4. Each HCC has a weight (coefficient) that contributes to the patient's RAF score

5. The RAF score determines the plan's reimbursement for that member

Example

A patient with Type 2 Diabetes Mellitus with diabetic chronic kidney disease would be coded as:

• E11.22, Type 2 diabetes mellitus with diabetic chronic kidney disease
• This maps to HCC 37 (Diabetes with Chronic Complications) in the V28 model
• HCC 37 carries a RAF weight that increases the patient's risk score

HCC Coding Models: V24 vs V28

CMS transitioned non-PACE organizations from the V24 model to the V28 model over a three-year phase-in. CY2026 is the first year their risk scores use V28 at full weight:

• V24 weight: 0% (the blend ended after PY2025)
• V28 weight: 100%

Key differences in V28:

• Many HCC categories were consolidated or removed
• Some conditions that were HCC-relevant in V24 are no longer mapped in V28
• New HCC categories were added for conditions like substance use disorders
• RAF weights were recalibrated across all categories

MEAT Criteria for HCC Coding

MEAT is a review mnemonic, not a universal CMS coding rule. Use it to organize documentation review, then apply the coding, encounter, program and payer requirements:

• Monitoring, The provider is monitoring the condition (labs, exams, assessments)
• Evaluating, The provider is evaluating the condition's status or progression
• Assessing, The provider documents their clinical assessment of the condition
• Treating, The provider is actively treating the condition (medications, therapies, referrals)

A past-medical-history entry does not automatically establish or rule out reportability. Review whether the record supports a current condition and whether the applicable coding, encounter, program and payer requirements are met.

How HCC Buddy Helps

HCC Buddy is built specifically for HCC coders. Every lookup in the encoder shows:

• The current source-backed mapping status and every listed HCC when mapped
• The CY2026 V28 factor and historical PY2025 V24 factor, when each source is verified
• Includes, Excludes 1, and Excludes 2 notes
• An Ask Buddy that can answer MEAT criteria and coding guideline questions

Try it free, search an ICD-10-CM code and check its source-labeled mapping status at hccbuddy.com/encoder.

Free resource: Download the HCC Coding Cheat Sheet, a printable V28 quick reference with top HCC categories and documentation tips.