Navigating the transition to V28: Impact in 2025

2025 is the tipping point for risk adjustment. This year marks the full coding transition to CMS’s new HCC risk adjustment model. The transition from V24 to V28 Hierarchical Condition Category (HCC) risk adjustment models marks a significant shift in how risk scores are calculated for Medicare Advantage patients. While the payment model won’t be fully felt by provider organizations and health plans until 2026, the actions they take today–the diagnoses captured or missed–will determine their future reimbursement.

V28 marks a major change to how risk is measured and how value-based organizations are funded. Some diagnoses that previously drove RAF scores no longer count, while others are newly weighted under V28 and have become essential to capture. The early data is clear: those who’ve invested in the right tools and workflows are already pulling ahead.

In this post, we’ll break down what’s changed, how the transition is playing out in real-world data, and how leading organizations are using Navina’s AI solution to stay ahead to mitigate V28’s impact and stay ahead of the curve.

What are CMS HCC models and why the shift to V28?

CMS HCC models are the formulas used to calculate risk scores for patients based on their diagnoses and demographics. In Medicare Advantage, every diagnosis code a provider documents maps to an HCC category, and each HCC contributes to a patient’s RAF score. The higher the RAF score, the more complex (and costly) the patient’s care is expected to be, which in turn influences reimbursement to health plans and provider groups. 

However, healthcare evolves quickly – new conditions emerge, coding practices change, and some diagnoses turn out not to drive costs as much as previously thought. CMS introduced V28 to improve the accuracy and fairness of risk adjustment. The V28 model is built on more recent data and on ICD-10 codes rather than legacy ICD-9 mappings. By rebuilding the model with updated diagnosis and cost data, V28 aims to better reflect current disease patterns, treatment methods, and true cost drivers.

Phased transition timeline 

A change this significant can’t happen overnight. CMS opted to phase in the V28 model over time to give plans and providers time to adjust. The phase-in began in 2024 and will be complete by 2026. In practical terms, payment year 2024 risk scores were still mostly calculated with V24, with a small portion using V28. For payment year 2025 (based on 2024 dates of service), the weighting shifted more toward V28. By payment year 2026, risk scores will be 100% based on V28, fully replacing V24.

As of 2025, organizations are coding patients entirely using the V28 model; only V28-mapped codes count moving forward, even though 2025 payments still reflect some blend of the old model. This approach has provided some predictability and stability during the change. Plans and providers have had a chance to see the impact gradually and adjust workflows accordingly. 

Key differences between HCC V24 and V28

So what exactly changed from V24 to V28? In a nutshell, V28 is a more refined and selective model. The number of HCC categories increased from 86 in V24 to 115 in V28, reflecting more granular groupings of conditions. At the same time, the total number of diagnosis codes that map to any HCC actually dropped significantly – down to about 7,770 codes in V28 from 9,797 in V24. 2,294 diagnosis codes deemed less predictive of costs no longer map to an HCC, while only 268 new codes were added. In other words, many diagnoses that would boost RAF in V24 no longer do in V28, and a smaller set of new diagnoses will now count toward risk scores.

What was removed?

Generally, V28 drops some lower-severity or resolved conditions that were weighted in V24. For example, diagnoses like stable or unspecified angina pectoris (chronic chest pain) and mild or remission-stage mental health disorders (e.g. depression or bipolar disorder in full remission) no longer map to an HCC in V28. Certain substance use disorder codes (like uncomplicated alcohol or cannabis abuse) were removed as well. Some acute conditions that might not indicate prolonged costs, such as acute kidney injury (acute kidney failure), were also taken out of the model. Some relatively minor procedures or complications, like toe amputations or vascular disease without complication, were dropped. The thinking behind this is that these conditions either resolve or don’t carry the same weight for future costs, and including them was inflating risk scores under V24 without corresponding cost increases.

What was added or changed?

V28 introduced new HCC categories to capture serious chronic conditions and complexities that weren’t separately recognized before. Notable new HCCs include Severe Persistent Asthma (HCC 279) and Pancreas Transplant Status (HCC 35). The 268 ‘new’ diagnosis codes include severe asthma with complications, alcoholic hepatitis, eating disorders like anorexia/bulimia, and rare diseases like Wilson’s disease are now risk-adjustable. In addition, several existing HCCs were split into more granular categories. A good example is Congestive Heart Failure (CHF) – under V24, CHF was a single category, but in V28 it’s split into five categories based on severity and ejection fraction, to more precisely reflect how severe heart failure is. Similarly, Chronic Kidney Disease Stage 3 was split into 3a and 3b, and Dementia was divided into mild, moderate, severe (HCCs 125–127). These changes encourage providers to document the severity level, not just the presence of a condition.

Overall, the trend with V28 is toward more specific coding and a tighter scope of what counts toward RAF, demanding higher documentation specificity to ensure that the patient's illness burden is accurately captured. Conditions that truly drive costs (progressive chronic diseases, severe or ongoing conditions) are emphasized, while diagnoses that are incidental or well-controlled (and thus less costly) contribute less or not at all. 

The impact of V28 in 2025: Lower RAF scores across the board

By mid-2025, we’re well into this transition, and its effects are being felt in both provider organizations and health plans. One immediate outcome is that average RAF scores are generally lower than they would have been under V24, because patients are accumulating fewer risk points on average. In fact, UnitedHealth Group cited the new V28 model as a factor contributing to a drop in their early 2025 Medicare Advantage earnings.

Under V28, providers might see lower risk scores for their panels even if the patient population’s health status hasn’t changed. For provider groups in value-based care arrangements, the concern is that lower RAF could translate to lower revenue or budget for managing patients. Many organizations have indeed observed a dip in their population-level RAF in 2024 and 2025 as the new model phases in. The drop is by design – CMS intended to recalibrate and reduce overpayment – but it puts pressure on documentation and coding teams to accurately capture every relevant diagnosis to avoid any unnecessary loss of RAF points.

How technology is mitigating the RAF drop

The good news is that while the V28 model sets a new bar, organizations equipped with Navina’s advanced AI solution are mitigating the impact. Navina uses AI to analyze patient data and surface chronic conditions or gaps in documentation, helping providers ensure no important diagnosis is overlooked during a visit. This technology is crucial under V28 because it identifies those high-value conditions, including the new V28-added codes, that providers might miss.

Data from Navina’s network of partner organizations shows several encouraging trends:

• There was a 106% year-over-year increase in the capture of “V28-only” codes among the same cohort of patients. In other words, providers using Navina are documenting twice as many of these newly important conditions as they did before – a positive sign that we’re adapting to the new model. This increase indicates Navina’s success in flagging these conditions during patient encounters.
  
  
• Providers who used Navina more frequently achieved a 45% higher RAF increase for their patients compared to providers who used the platform less. This indicates that consistent use of AI assistance leads to more comprehensive coding of chronic conditions, directly cushioning the blow of the V28 model changes.
  
  

One Navina partner organization saw that over a two-year period, the average RAF per patient still rose by 0.34 when using the V28 model – whereas under V24 those same patients’ RAF would have risen by 0.56 in two years. While the RAF growth was smaller with V28, thorough coding supported by AI allowed them to achieve a positive gain. Without such efforts, many groups might have seen flat or negative RAF trends.

Forward-thinking organizations in 2025 are learning to work smarter within the new model. Provider education has been key, as clinicians and their staff learn the nuances of the new codes. For example, accurately recognizing (and documenting) a condition like severe asthma or chronic kidney disease stage 3b in a patient can now make a tangible difference in their risk score. Navina’s AI serves as a powerful copilot, identifying these potential diagnoses deep within patient records and bringing them to the provider’s attention. 

The result: even though V28 shrinks the pool of countable diagnoses, providers can still succeed by capturing the full complexity of the patient’s health status that V28 is designed to reward.

Thriving under V28: A new normal for risk adjustment

The transition from HCC V24 to V28 is reshaping how risk adjustment is done, and 2025 is a pivotal year in that regard. CMS’s rationale for V28 was to make risk scores more accurate and cost-reflective, even if that means lower RAF scores overall. We’ve seen that play out: many organizations saw a dip in risk scores as V28 removed a swath of previously weighted diagnoses. The model is more demanding – it asks providers to document conditions at a higher level of specificity and focuses only on diagnoses that truly drive cost of care.

Yet with challenge comes opportunity. The V28 transition has prompted providers and health plans to improve their coding practices and invest in better tools. Those who have embraced AI-assisted coding and clinical review are finding that they can offset much of the RAF compression. By surfacing the evidence for relevant conditions and ensuring nothing important slips through the cracks, Navina enables organizations to continue closing care gaps and capturing the risk profile of patients effectively. The gap between organizations that optimize coding accuracy and those that don’t is widening. High-performing groups are retaining more of their risk score by diligently coding V28 conditions, whereas others risk falling behind.

Ultimately, as we fully adopt V28, the playing field resets to a new normal. RAF scores will be generally leaner, but also more accurate. Organizations that thrive will be those that use advanced analytics and AI to maximize appropriate coding – which in turn supports better care, since capturing a condition is often the first step to addressing it. With the right strategy and tools, providers and health plans can navigate the transition and continue to succeed in a value-based care world. The key is to stay informed, leverage technology, and focus on what matters most: the truly impactful health conditions of each patient.