HCC V28 Changes Explained: V24 vs V28 and What Applies in 2026 and 2027

By Jay Chowdappa, MD, co-founder and CEO, Zynix AI · Updated October 30, 2026

Key takeaways

V28 is the 2024 CMS-HCC risk adjustment model. CMS rebuilt the condition categories on ICD-10, raising payment HCCs from 86 to 115, recalibrated on 2018 diagnoses and 2019 costs, constrained the diabetes and milder heart failure HCCs, and removed categories such as protein-calorie malnutrition and angina pectoris. It was phased in from 2024 to 2026 and stays in use for 2027.

• Medicare Advantage risk scores blended V24 and V28 at 67/33 in 2024 and 33/67 in 2025, and used V28 alone from 2026.
• For 2027, CMS kept the 2024 model as is: the recalibration it proposed in January 2026 was not finalized.
• New for 2027: diagnoses from unlinked chart review records and from audio-only services are excluded from MA risk scores.
• Shared Savings Program ACOs in agreement periods that began on or after January 1, 2024 have benchmark-year risk scores recalculated with the model that applies to the performance year.

What is the CMS-HCC V28 model?

The CMS-HCC model turns a beneficiary's demographics and diagnoses into a risk score that adjusts Medicare Advantage payments. It is prospective: diagnoses from one year predict costs in the next, which is why V28 was calibrated on 2018 diagnosis data and 2019 fee-for-service expenditures. The model it replaced, the 2020 CMS-HCC model (V24), was calibrated on 2014 diagnoses and 2015 expenditures.

CMS describes three technical updates in V28: newer data years, a newer denominator year, and a clinical reclassification of the hierarchical condition categories using ICD-10-CM. As part of the reclassification, CMS reviewed conditions coded much more often in Medicare Advantage than in fee-for-service Medicare, under its long-standing model principle that discretionary diagnostic categories should be excluded from payment models. V28 keeps the same structure as V24: eight model segments and condition-count variables.

V24 vs V28: what changed

The changes that matter most for documentation and revenue are the larger HCC set, the constraints, and the categories that no longer pay.

Constraining HCCs means CMS holds their coefficients equal, so a more severe code in the group adds no more to the risk score than a milder one. For diabetes, CMS said the constraint lets expenditures flow to well-defined complications captured in other payment HCCs, such as chronic kidney disease and diabetic eye disease.

How was V28 phased in?

CMS phased V28 in over three years for Medicare Advantage risk scores (organizations other than PACE):

PACE organizations follow a different schedule. For 2027, CMS calculates PACE risk scores as 50% from the 2024 model and 50% from the 2017 model.

What changes for HCC risk adjustment in 2027?

The model stays the same in 2027; the rules about which diagnoses count changed. In the CY 2027 Rate Announcement (April 6, 2026), CMS:

• Kept the 2024 CMS-HCC model for non-PACE organizations. The January 2026 Advance Notice had proposed recalibrating it with 2023 diagnoses and 2024 expenditures; CMS did not finalize that for 2027 and said it will evaluate model refinements for the future.
• Excluded diagnoses from unlinked chart review records, with an exception for beneficiaries who switch from one MA organization to another.
• Excluded diagnoses from audio-only services, identified by modifier 93 or FQ.
• Set the 2024 model normalization factor at 1.079 and applied the statutory minimum MA coding pattern difference adjustment of 5.90%.

The practical effect: to count toward a 2027 Medicare Advantage risk score, a diagnosis must come from a risk adjustment-eligible encounter that was not audio-only, and a chart review diagnosis must be linked to an encounter.

Does V28 affect ACOs in the Shared Savings Program?

Yes. The Shared Savings Program uses prospective CMS-HCC risk scores in its benchmark calculations. In the CY 2024 Physician Fee Schedule final rule, CMS finalized that for ACOs in agreement periods beginning on or after January 1, 2024, benchmark-year risk scores are calculated with the CMS-HCC risk adjustment methodology for the calendar year that corresponds to the performance year (42 CFR 425.659). Benchmark and performance years are therefore scored with the same model, so V28's reclassification shows up on both sides of the comparison.

For how ACOs turn this into year-round documentation work, see HCC gap closure for ACOs under V28.

What V28 means for documentation

V28 rewards specific, well-supported documentation of conditions that still map to payment HCCs, every year, at a qualifying visit. Four habits follow from the changes above:

1. Document severity where it changes the HCC. For heart failure, the severity split matters; for diabetes, the documented complications that map to their own HCCs, such as chronic kidney disease, matter more than the diabetes code's own severity.
2. Do not chase removed categories for payment. Malnutrition, stable angina and claudication still belong in the record when clinically present, but they no longer add to the V28 risk score.
3. Capture conditions at qualifying encounters. For 2027, diagnoses from audio-only services and from unlinked chart review records do not count toward MA risk scores.
4. Recapture every year. Because the model is prospective, a chronic condition documented last year does not carry into next year's score unless it is documented again.

The Annual Wellness Visit and regular chronic care visits are the natural places to review every active condition. Zynix AI's HCC gap closure workflow for ACOs ranks open gaps, prepares clinicians before scheduled visits and invites patients with no visit booked. Clinicians decide what to document and coders decide what to submit; the software never chooses codes. Health plans can see the member-facing version in risk adjustment outreach for MA plans.

This guide summarizes Medicare rules as CMS published them as of October 30, 2026. It is not legal or coding advice. CPT is a registered trademark of the American Medical Association. Check current CPT guidance, your Medicare Administrative Contractor (MAC) and each payer's policy before you change billing.

Frequently asked questions

What is HCC V28?

HCC V28 is the 2024 CMS-HCC risk adjustment model that CMS uses to set Medicare Advantage risk scores. It reclassified condition categories on ICD-10-CM, increased payment HCCs from 86 to 115, recalibrated on 2018 diagnoses and 2019 costs, constrained the diabetes and milder heart failure HCCs, and removed categories such as protein-calorie malnutrition and angina pectoris from payment.

When did V28 fully replace V24?

In 2026. CMS phased V28 in over three payment years: risk scores were 33% V28 and 67% V24 in 2024, 67% V28 and 33% V24 in 2025, and 100% V28 from 2026. For 2027, CMS kept the 2024 model for organizations other than PACE. PACE organizations use a 50/50 blend of the 2024 and 2017 models in 2027.

Is CMS changing the HCC model for 2027?

Not the model itself. CMS proposed recalibrating V28 with 2023 diagnoses and 2024 costs but did not finalize it in the April 2026 Rate Announcement. It did finalize two changes to which diagnoses count: diagnoses from unlinked chart review records and from audio-only services are excluded from 2027 Medicare Advantage risk scores.

Which conditions were removed from payment in V28?

CMS's 2024 Rate Announcement names protein-calorie malnutrition, angina pectoris (moved to a non-payment HCC while unstable angina still pays) and atherosclerosis of the extremities with intermittent claudication. CMS also moved some discretionary diagnosis codes into non-payment categories during the ICD-10 reclassification. Check the published V28 mappings for individual ICD-10-CM codes.

Does V28 apply to ACOs?

Yes. Shared Savings Program ACOs in agreement periods that began on or after January 1, 2024 have benchmark-year risk scores calculated with the CMS-HCC methodology for the calendar year of the performance year, so the benchmark and performance year use the same model. Documentation habits that support Medicare Advantage risk scores also support accurate ACO benchmarks.

Related reading

• The New Era of HCC Risk Adjustment: What CMS Changes Mean for Providers
• Transforming HCC Risk Adjustment: From Q4 Scramble to Year-Round Success
• Year-End ACO Gap Closure: How ACOs Can Close Gaps Faster With Zynix AI

Source notes

CMS (March 31, 2023): Announcement of Calendar Year 2024 Medicare Advantage Capitation Rates and Part C and Part D Payment Policies. https://www.cms.gov/files/document/2024-announcement-pdf.pdf

CMS (April 6, 2026): Announcement of Calendar Year 2027 Medicare Advantage Capitation Rates and Part C and Part D Payment Policies. https://www.cms.gov/files/document/2027-announcement.pdf

Federal Register, 88 FR 78818 (November 16, 2023): CY 2024 Payment Policies Under the Physician Fee Schedule, final rule (Shared Savings Program risk scores, 42 CFR 425.659). https://www.federalregister.gov/documents/2023/11/16/2023-24184/medicare-and-medicaid-programs-cy-2024-payment-policies-under-the-physician-fee-schedule-and-other

About the author

Jay Chowdappa, MD is co-founder and CEO of Zynix AI. He is a physician, and ACOs led by him generated $300M+ in shared savings before he started Zynix AI to help care teams follow through on what their data already shows.