March 18, 2026

Medical Coding: Risk Adjustment Model V28

AAPC | Certification | Certified Medical Coder | CPC | Medical Coding
By Janine Mothershed

What Coders Need to Know (Guidelines & Tips)

The transition to the CMS-HCC Risk Adjustment Model V28 is one of the most important changes impacting Medicare Advantage and risk adjustment coding in recent years.

If you work in HCC coding, auditing, CDI, or value-based care, this update directly affects how diagnoses translate into RAF (Risk Adjustment Factor) scores and reimbursement.

What is Risk Adjustment?

Risk adjustment is used by CMS to ensure that healthcare plans are paid appropriately based on the complexity and health status of their patients.

  • Sicker patients = higher RAF scores = higher reimbursement

  • Healthier patients = lower RAF scores

CMS uses the Hierarchical Condition Category (HCC) model to calculate these scores.

What is V28?

V28 is the updated CMS-HCC model designed to improve accuracy and reflect more current patient data, coding practices, and healthcare costs.

Key goal:

  • Improve payment accuracy

  • Reduce coding variation and overcoding

  • Better align with ICD-10-CM

CMS introduced V28 with a 3-year phase-in (2024–2026) and it is now fully implemented (100%).

Major Changes in V28

ICD-10-Based Model

V28 is fully built on ICD-10 coding logic.

  • More clinically specific

  • More precise disease grouping

  • Requires stronger documentation support

Expanded and Restructured HCC Categories

  • Increased from ~86 HCCs to ~115 HCCs

  • Conditions regrouped based on clinical similarity and cost patterns

Reduced Number of Valid Diagnoses

Not all diagnoses that mapped to HCCs in V24 still map in V28.

  • Some conditions no longer risk-adjust

  • Others were consolidated or removed

This means:

  • Less opportunity for RAF capture

  • Greater emphasis on accurate condition specificity

Lower RAF Scores Expected

CMS projected a decrease in overall risk scores:

  • Estimated ~3%+ decrease initially

  • Many organizations are seeing 3–8% RAF reductions

Updated Data & Methodology

V28 uses:

  • Newer fee-for-service data (2018–2019)

  • Improved predictive modeling

  • Refined cost relationships

Why This Matters for Coders

This is not just a “model update”—it changes how coders must think.

Under V28:

  • Documentation must be more precise

  • Coding must be fully supported and clinically valid

  • “Coding everything possible” is no longer effective

Risk Adjustment Coding Guidelines for V28

Code to the Highest Level of Specificity

  • Avoid unspecified codes when possible

  • Capture complications and manifestations

Example:

  • Diabetes without complications vs. diabetes with CKD → major RAF difference

Ensure MEAT Criteria are Met

Every HCC diagnosis must be supported by:

  • Monitoring

  • Evaluation

  • Assessment

  • Treatment

If it’s not documented, it doesn’t count.

MEAT 

SOAP 

Capture Chronic Conditions Annually

HCC conditions must be coded every year.

  • Chronic conditions do NOT carry over

  • Must be documented and coded at least once per calendar year

Acute vs Chronic in Medical Coding 

Medical Coding for Chronic Conditions 

Focus on Active Conditions Only

Do NOT code:

  • History of conditions (unless applicable HCC)

  • Resolved conditions

  • Rule-out diagnoses

Validate Clinical Accuracy

With V28, CMS is placing greater emphasis on:

  • Clinical validity

  • Audit defensibility

  • Risk Adjustment Data Validation (RADV) readiness

High-Impact Coding Areas in V28

Coders should pay close attention to:

  • Diabetes (fewer qualifying combinations)

  • CKD staging (must be documented clearly)

  • Heart failure types (systolic vs diastolic vs combined)

  • COPD vs asthma specificity

  • Malnutrition and morbid obesity documentation

Practical Tips for Coders

Documentation Drives Revenue

V28 reduces “coding opportunities,” so documentation matters more than ever.

Don’t Rely on Old HCC Lists

Many V24 mappings no longer apply.

Always verify:

  • Does this code still map to an HCC in V28?

Query When Needed

If documentation is unclear:

  • Query the provider

  • Clarify severity, type, or linkage

Think Like an Auditor

Ask yourself:

  • Would this diagnosis pass a RADV audit?

Educate Providers

Providers must understand:

  • Specificity matters

  • Chronic conditions must be documented annually

  • Unsupported diagnoses will not count

The Bottom Line

The transition to V28 is a shift toward accuracy over volume.

  • Fewer diagnoses qualify for HCCs

  • RAF scores may decrease

  • Documentation and clinical validation are critical

This model rewards:

  • Accurate coding

  • Strong documentation

  • True patient complexity

Final Takeaway for Coders

If you want to stay competitive in risk adjustment:

  • Master HCC mapping changes

  • Strengthen documentation review skills

  • Understand value-based reimbursement models

Because in V28, precision is everything.

CMS Risk Adjustment  

Revised CMS-HCC Model Relative Factor Tables 

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