Top 10 Most Common HCC Codes Every Coder Should Know

Top 10 Most Common HCC Codes Every Coder Should Know

Risk adjustment coders encounter certain HCC categories far more often than others. Mastering these high-frequency codes — and the ICD-10-CM codes that map to them — will make you faster, more accurate, and more valuable to your organization.

This list is based on the CMS-HCC V28 model, which is being phased in for Payment Year 2026.

1. HCC 37 — Diabetes with Chronic Complications

Diabetes is the single most commonly coded HCC category. In V28, most diabetes complications consolidate under HCC 37.

Key ICD-10-CM codes:

Documentation tip: Always capture the type of diabetes, the specific complication, and laterality where applicable.

2. HCC 221 — Heart Failure

Heart failure remains one of the highest-weighted HCC categories, reflecting the significant cost of managing these patients.

Key ICD-10-CM codes:

Documentation tip: Specify acuity (acute, chronic, or acute-on-chronic) and type (systolic, diastolic, or combined). "Heart failure" alone defaults to I50.9, which does NOT map to an HCC.

3. HCC 326 — Chronic Obstructive Pulmonary Disease

Chronic Obstructive Pulmonary Disease is consistently among the top coded conditions in Medicare Advantage populations.

Key ICD-10-CM codes:

Documentation tip: Document whether the patient is in stable state or experiencing an exacerbation. Capture any coexisting conditions like Asthma.

4. HCC 238 — Atrial Fibrillation

Atrial fibrillation is extremely common in elderly populations and maps to HCC 238 in V28.

Key ICD-10-CM codes:

Documentation tip: Specify the type of atrial fibrillation (paroxysmal, persistent, chronic/permanent). Also document whether it is controlled or uncontrolled.

5. HCC 328 — Morbid Obesity

Morbid obesity (Body Mass Index 40+) maps to HCC 328 in V28 and is frequently encountered.

Key ICD-10-CM codes:

Documentation tip: Always pair E66.01 with the specific Body Mass Index Z code. The Body Mass Index must be documented in the same encounter.

6. HCC 85 — Congestive Heart Failure

Distinct from general heart failure, this category captures specific congestive presentations.

Key ICD-10-CM codes:

Documentation tip: When a patient has both hypertension and heart failure, code the combination code. CMS presumes a causal relationship between hypertension and heart disease.

7. HCC 18 — Pancreatic Cancer and Other Severe Cancers

Active malignancies carry some of the highest RAF weights in the model.

Key ICD-10-CM codes:

Documentation tip: Only code active malignancies. If the cancer is in remission, history of, or has been excised, use the appropriate Z85 history code instead, which typically does not map to an HCC.

8. HCC 115 — Chronic Kidney Disease, Stage 4

Advanced chronic kidney disease stages carry significant HCC weight due to the cost of managing these patients.

Key ICD-10-CM codes:

Documentation tip: Document the specific stage. "Chronic kidney disease" without a stage defaults to N18.9 (unspecified), which maps to a lower-weighted HCC or none at all.

9. HCC 161 — Chronic Ulcer of Skin, Except Pressure

Chronic skin ulcers are common in diabetic and vascular patients and map to their own HCC.

Key ICD-10-CM codes:

Documentation tip: Capture the exact location, laterality, and severity (limited to skin breakdown, fat layer exposed, necrosis of muscle, necrosis of bone, etc.).

10. HCC 135 — Major Depression

Mental health conditions, particularly major depression, are increasingly captured in risk adjustment.

Key ICD-10-CM codes:

Documentation tip: Specify single episode vs. recurrent, and severity (mild, moderate, severe). Document whether it is with or without psychotic features.

Quick-Reference Table

*Note: RAF weights are approximate and vary by model segment (community, institutional, etc.)*

Use HCC Buddy to Verify Mappings

Instead of memorizing every code-to-HCC mapping, use HCC Buddy's encoder to instantly verify whether any ICD-10-CM code maps to an HCC, see the RAF weight, and check which model version applies.

Free resource: Download the HCC Coding Cheat Sheet — a printable V28 quick reference with top HCC categories and documentation tips.