ICD-10 to HCC mapping — CMS-HCC V28 explorer

How ICD-10 codes map to HCCs under V28

CMS-HCC V28 groups 8,016 of the 74,719 billable FY2026 ICD-10-CM codes into 115 payment categories. Each category carries a coefficient that varies by population segment (community vs. institutional, dual status, aged vs. disabled). Only the highest-ranked HCC in a hierarchy counts, and only diagnoses documented face-to-face with supporting evidence survive audit. V28 is fully phased in as of payment year 2026 — the blend with V24 is gone.

FAQ

What is an HCC code?

Hierarchical Condition Categories (HCCs) are CMS risk-adjustment groupings of ICD-10-CM diagnosis codes. Under CMS-HCC V28 there are 115 payment HCCs; each documented, mapped diagnosis contributes a coefficient to a patient’s RAF score, which drives Medicare Advantage payment.

How many ICD-10 codes map to an HCC under V28?

8,016 ICD-10-CM codes map to a payment HCC in the V28 model for PY2026 — thousands fewer than under V24, which is why many practices saw RAF scores drop. 8,296 code-to-HCC pairs exist in total, because 280 codes map to two categories.

Does an HCC mapping mean the code is billable?

No. A code can carry an HCC mapping and still be unsubmittable — category headers such as G35 (multiple sclerosis) map to HCC 198, but a claim carrying G35 rejects; you have to code to a specific child such as G35.A. This tool labels any code that is a header or was retired before FY2026.

What is a RAF score?

The Risk Adjustment Factor is the sum of a patient’s demographic and HCC coefficients. A RAF of 1.0 represents average expected cost; documented HCCs raise it, and payment scales with it.

Why did a code that used to count stop counting?

The V28 model removed or re-grouped many diagnoses CMS judged weak cost predictors. If a code shows no V28 mapping here but paid under V24, it lost payment status in the transition.