What is an HCC code? The CMS-HCC V28 categories

How HCC risk adjustment works

Medicare Advantage plans are paid a capitated amount per member per month, and risk adjustment scales that amount to the member's expected cost. The CMS-HCC model starts with demographic factors for age, sex, Medicaid dual status, disability and institutional status, then adds a relative factor for each hierarchical condition category documented for the member during the previous calendar year. The sum is the raw risk score; CMS normalizes it so the average fee-for-service beneficiary scores 1.000, reduces it by the statutory coding intensity adjustment, and multiplies the result by the plan's county base rate. A member with a score of 1.5 therefore brings the plan half again the base payment, and every category that is documented and supported moves the score by exactly the factor shown on its page.

The model is hierarchical because related conditions are ranked by severity and only the most severe one counts. The factors are estimated separately for seven segments, so the same category is worth a different amount for a community-dwelling aged member with no Medicaid, a disabled member with full Medicaid, or a long-term institutional member; the category pages show all seven. V28, the current version, was calibrated on more recent cost data, renumbered the categories, dropped or constrained several that were driven more by coding than by cost, and has applied in full since payment year 2026. Diagnoses come from claims and encounter records submitted by the plan, and risk adjustment data validation audits sample them against the medical record.

Most searched HCC categories

Highest relative factors

Categories with the most mapped codes

All 115 CMS-HCC V28 categories

What makes a category count

Three things decide whether a category reaches the risk score. The diagnosis must be documented during the data collection year at a face-to-face or audio-video encounter by a physician or other acceptable provider type; diagnoses from diagnostic radiology, laboratory orders or durable medical equipment claims do not count on their own. The note must show that the condition was monitored, evaluated, assessed or treated, not just listed in the history, because that is the standard a risk adjustment data validation auditor applies when the chart is pulled. And the condition must be re-documented every year, since nothing carries forward. Suspect-condition workflows, annual wellness visits and problem-list reconciliation exist to close that gap, and the QuickIntell risk adjustment product reads the chart to surface categories that are supported but uncoded and categories that are coded but unsupported. The inpatient side of the same diagnoses appears on the MS-DRG reference, where many of the same codes act as complications and comorbidities.

Frequently asked questions

Sources

Every figure on this page is taken from the CMS publications below, as released by the Centers for Medicare & Medicaid Services. Projection built 2026-10-02. Verify against the primary file before billing or contracting decisions.

• ICD-10-CM to CMS-HCC V28 mappings, payment year 2027 initial
  Version PY2027 initial ICD-10-CM mappings (dates of service 2026) · effective 2027-01-01 · file 2027 Initial ICD-10-CM Mappings.csvSHA-256 9c260b06d0dd2806…
• CMS-HCC V28 model software: labels, hierarchies and relative factors
  Version CMS-HCC V28 software V2826.115.T2 (PY2027 initial) · effective 2027-01-01 · file C2824T2N.csvSHA-256 20f38d537493b41c…