What is CMS-HCC V24 Risk Adjustment Model? Definition, Formula, and Benchmark

CMS-HCC V24 is the risk-adjustment model CMS used for Medicare Advantage payment from payment year 2020 through 2023 and which continues to contribute to the blended payment calculation during the 2024 and 2025 V28 phase-in. V24 was an incremental update from V22, refining several condition categories to reflect observed cost patterns but retaining the broad HCC taxonomy that had been in place since 2013.

The V24 model contains approximately 86 HCC categories mapped from ICD-10-CM diagnoses, with disease-interaction terms that capture the additional cost impact when certain conditions co-occur (for example, diabetes with CKD). Coefficients were calibrated against 2014 FFS expenditure data with subsequent trending, and remained stable across the payment years V24 was in effect — a stability that let plans and providers build multi-year coding and documentation programs with confidence that the rules would not change underneath them.

V24 remains operationally relevant for several reasons. First, it is still blended with V28 during the transition window (67% V24 in 2024, 33% V24 in 2025), so current-payment calculations still reference V24 coefficients. Second, RADV and OIG audit work for payment years 2020–2023 continues to use V24 mappings to validate documentation. Third, multi-year retrospective financial analyses and actuarial risk-score reconciliations almost always compare current-year V28 reporting against V24 baselines to measure the model-change impact separately from membership and documentation effects.

A small number of ICD-10-CM diagnoses that mapped to an HCC in V24 no longer do in V28 — the approximately 2,294 delisted codes that drove much of the V28 RAF compression. Conversely, V28 introduced some new condition granularity (more specific dementia and renal failure subcategories) that did not exist separately in V24. Risk-adjustment teams often maintain parallel V24/V28 mappings during transition years so that suspect-condition lists, provider education materials, and RADV-defense binders remain usable across both models.

For operational RCM teams, the main V24 artifact worth preserving is the crosswalk document — the authoritative mapping of every ICD-10-CM code to its V24 HCC. CMS publishes the crosswalk as a downloadable file updated annually to reflect the ICD-10-CM code-set version in effect for each fiscal year. Third-party software vendors replicate this mapping in their code. Keeping the V24 crosswalk in your risk-adjustment tooling long after V28 becomes the single payment model is a practical necessity for historical audit support.

From a coding-compliance standpoint, CMS-HCC V24 Risk Adjustment Model lives at the intersection of CPT-category specificity, payer-specific guidance, and internal documentation standards. Practices that run a quarterly CMS-HCC V24 Risk Adjustment Model audit against cms hcc v28 and hierarchical condition category consistently close the coder-provider feedback loop faster than practices that wait for the annual OIG or payer audit to surface the pattern. Reviewers on this site flag CMS-HCC V24 Risk Adjustment Model entries whenever payer guidance shifts materially so the associated claim-scrubber logic is updated before the next billing cycle.