ICD-10 to HCC mapping — CMS-HCC V28 explorer
Enter an ICD-10-CM code to see its V28 payment HCC and PY2026 RAF coefficients across all seven population segments. Codes are the FY2027 ICD-10-CM set (effective October 1, 2026); mappings and weights are the CMS PY2026 V28 files.
How ICD-10 codes map to HCCs under V28
CMS-HCC V28 maps 8,016 ICD-10-CM codes into 115 payment categories — the PY2026 mapping, which covers codes valid in FY2025 and FY2026. The FY2027 set that took effect October 1, 2026 has 74,879 billable codes; CMS maps the new ones in its Midyear/Final release. 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 has been retired, with the date it stopped being billable.
- 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.