The Code Still Exists. The HCC May Not: V28 Mappings Coders Should Recheck

Quick Answer

A code being valid in the ICD-10-CM code set doesn't mean it still maps to a payment HCC under the current Medicare Advantage model.

CMS says the 2024 CMS-HCC model reduced the number of ICD-10-CM codes mapped to payment HCCs from 9,797 (in the 2020 CMS-HCC model) to 7,770, with 2,236 codes no longer mapped to payment HCCs. That's not a minor cleanup. It means a code a coder has used safely for years can still be HIPAA-valid, still be clinically correct, and still contribute exactly zero to current-year RAF.

Payment Year 2026 runs 100% V28. The V24 blend is gone. If your reference materials, training decks, or old tip sheets haven't been rebuilt against the current CMS mapping files, they're a liability.

How Big Is the V28 Mapping Shift?

Big enough that old instincts aren't safe anymore.

In its December 2024 Report to Congress, CMS says the 2024 CMS-HCC model (V28) maps 7,770 ICD-10-CM codes to payment HCCs, down from 9,797 in the 2020 CMS-HCC model (V24). Of the 2,236 codes that dropped out, CMS says 96.6% came from ICD-10-CM clinical updates rather than a targeted policy decision.

The practical takeaway: most of the dropped codes didn't disappear because CMS decided those conditions don't matter. They disappeared because ICD-10-CM added more specific codes over the years and the mapping didn't follow the old catch-all into V28. That makes this a specificity problem as much as a model-change problem.

Which Familiar Code Families Lost Payment HCC Status?

Angina codes are the clearest example

In the official CMS mapping files, I20.9 (angina pectoris, unspecified) mapped to V24 HCC 88 ("Angina Pectoris"). In the current V28 final mapping, that code carries no payment HCC.

The same pattern holds for I20.1 (angina pectoris with documented spasm), I20.89 (other forms of angina pectoris), and coronary atherosclerosis codes that include angina language like I25.119 — all carry no V28 payment HCC. If the chart only supports angina without heart failure or acute MI, the old HCC doesn't follow the code into 2026 payment.

Unspecified PVD and claudication codes got much less forgiving

V24 rewarded a broad vascular bucket. V28 doesn't.

I73.9 (peripheral vascular disease, unspecified) mapped to V24 HCC 108 ("Vascular Disease") but has no V28 payment HCC. The same is true for I70.213 (atherosclerosis of native arteries of extremities with intermittent claudication, bilateral legs) — no V28 payment HCC.

The family didn't disappear entirely, though. More severe vascular disease still maps. I70.233 (atherosclerosis of native arteries of the right leg with ulceration of ankle) and I70.263 (atherosclerosis of native arteries of extremities with gangrene, bilateral legs) both map to V28 HCC 263 ("Atherosclerosis of Arteries of the Extremities with Ulceration or Gangrene").

The difference between I70.213 (no HCC) and I70.233 (HCC 263) is specificity and severity, not just the disease label. If the chart documents ulceration, the mapping is there. If the note stays at claudication only, it isn't.

Mild or unspecified depression lost the old automatic HCC path

The depression family is another place where coding from habit gets expensive.

In the CMS mapping files:

The pattern is consistent across these families: the diagnosis may survive in V28, but the vague or lower-acuity version doesn't carry an HCC anymore.

Which Codes Still Map — But Not the Way Coders Expect?

This is the second trap. Some codes still carry a payment HCC under V28, but not the same one, and the coding lesson changed.

Diabetes is the best example. In the official CMS comparison files:

The coder who treats hyperglycemia as equivalent to a chronic complication is overestimating the HCC result. E11.65 still maps, but it doesn't land where V24-era habits would expect, because it no longer represents a chronic-complication tier under V28. If the chart supports diabetic CKD or diabetic neuropathy, code those — they still reach HCC 37.

See the diabetes HCC coding guide for the full complication-linkage picture.

What Should Coders Recheck First?

Recheck codes that used to be safe shorthand

I20.9, I73.9, and mild or unspecified depression codes are the ones most likely to still be sitting on old tip sheets and old audit tools. They're valid codes. They just don't carry a payment HCC anymore.

Check whether the chart supports a more specific vascular or depression code

If the provider documented ulceration, gangrene, moderate depression, or severe depression, the mapping may still be there. That means a coder's first job in these families isn't to accept the unspecified code — it's to check whether the note actually supports something more specific.

Don't assume every diabetic detail raises the HCC tier

The difference between E11.65 (V28 HCC 38) and E11.22 (V28 HCC 37) is whether a documented chronic complication with linkage exists. Hyperglycemia alone maps, but to the lower category. If the chart supports diabetic CKD or neuropathy, the documentation needs to say so clearly and the coder needs to capture it.

Check current CMS files, not old slide decks

If a local spreadsheet, training note, or vendor export says a familiar code is still an HCC, compare it against the official CMS mapping file for the current payment year before trusting it. The RADV risk is real: a code that paid under V24 but not under V28 is still a valid code. An auditor doesn't care that the old training said it was fine.

Use the RAF calculator at /raf if you want to see the payment impact of a mapping change before you finalize a coding decision.

Why This Matters For Coding Managers and QA Leads

These mapping shifts change more than RAF math.

They change query patterns, coder education, and QA focus. A team can look accurate on basic ICD-10-CM assignment and still miss the real V28 issue if coders are working from familiar diagnosis labels instead of current CMS payment mappings. In 2026, "valid code" and "payment HCC" are related questions. They're not the same question.

The most common way this surfaces in a QA pass: a coder coded the right ICD-10-CM code for what was documented, the documentation is solid, and the code is HIPAA-valid. The HCC is just gone. That's not a coding error in the traditional sense. It's a model-change gap that only shows up when someone checks the current mapping file.

Where HCC Buddy Fits

HCC Buddy lets you check that second question without a separate lookup: you can verify the ICD-10-CM code is valid, see the current V28 HCC mapping (or the absence of one), and catch where a familiar diagnosis lost its old payment path.

It doesn't replace coder judgment or documentation review. It surfaces the current CMS mapping so you're not working from memory or last year's reference sheet.

Try it on a code you're not sure about: Check a code path in the encoder.

Also see the ICD-10 to HCC mapping hub for a broader reference on which codes carry payment HCCs and which don't.

Sources

CMS 2026 Model Software and ICD-10 Mappings

CMS 2024 Model Software and ICD-10 Mappings

CMS Report to Congress: Risk Adjustment in Medicare Advantage, December 2024

HCC Buddy V24 vs V28 guide

HCC Buddy ICD-10 codes not mapping to HCC reference

HCC Buddy diabetes HCC coding guide