Morbid Obesity HCC Coding Guide
Morbid Obesity (e.g. E66.2) maps to HCC 48 (Morbid Obesity) under the CMS-HCC V28 risk adjustment model, with a community, non-dual, aged RAF weight of 0.186; V28 reached 100% phase-in for payment year 2026. E66.09, other obesity due to excess calories, is non-HCC under V28.
Complete HCC coding guide for Obesity and Morbid Obesity (E66.x) including ICD-10 to HCC mapping, BMI documentation, V28 RAF weights, and coding requirements.
Medically reviewed by Jess P., CPC · Reviewed: May 10, 2026 · Updated for CMS-HCC V28 and FY2026 ICD-10-CM
Quick Facts
HCC Categories
HCC 48, Morbid Obesity
RAF Weight Range
0.186
Community, non-dual, aged (V28)
Model
CMS-HCC V28 (PY2026, 100% phase-in)
7 ICD-10 codes map to payment HCCs
What HCC category does Morbid Obesity map to under V28?
Obesity affects over 42% of US adults, and morbid (severe) obesity is a payment condition under the CMS-HCC V28 model. General obesity codes do not map to a payment HCC, but the morbid obesity codes do. Under V28, three ICD-10 codes map to HCC 48 (Morbid Obesity): E66.01 (morbid obesity due to excess calories), E66.2 (morbid obesity with alveolar hypoventilation), and E66.813 (obesity, class 3). HCC 48 carries a community non-dual aged RAF of 0.186. Accurate capture requires the provider to document the clinical diagnosis of morbid, severe, or class 3 obesity, the current BMI value, and the treatment plan. A BMI code (Z68.4x) alone never maps to an HCC, it only supports the obesity diagnosis. Query the provider when the BMI indicates severe obesity but the note only says "obesity."
ICD-10 to HCC Mapping
| ICD-10 Code | Description | Billable | HCC Mapping |
|---|---|---|---|
| E66.01 | Morbid (severe) obesity due to excess calories | Yes | HCC 48 |
| E66.2 | Morbid (severe) obesity with alveolar hypoventilation | Yes | HCC 48 |
| E66.09 | Other obesity due to excess calories | Yes | No HCC (not risk-adjusting under V28) |
| E66.1 | Drug-induced obesity | Yes | No HCC (not risk-adjusting under V28) |
| Z68.41 | Body mass index [BMI] 40.0-44.9, adult | Yes | HCC 48 |
| Z68.42 | Body mass index [BMI] 45.0-49.9, adult | Yes | HCC 48 |
| Z68.43 | Body mass index [BMI] 50.0-59.9, adult | Yes | HCC 48 |
| Z68.44 | Body mass index [BMI] 60.0-69.9, adult | Yes | HCC 48 |
| Z68.45 | Body mass index [BMI] 70 or greater, adult | Yes | HCC 48 |
| E66.8 | Other obesity | Yes | No HCC (not risk-adjusting under V28) |
RAF weights are community, non-dual, aged base coefficients from the CMS-HCC V28 model (PY2026). Verify against the latest CMS rate announcement for payment calculations.
HCC Buddy maps Morbid Obesity from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Documentation Tips
Document the clinical diagnosis of 'morbid obesity' or 'severe obesity', a BMI code alone does not support an HCC-mapped diagnosis code.
Always include the current BMI value in the encounter note alongside the obesity diagnosis.
Use E66.01 (morbid obesity due to excess calories) as the primary obesity diagnosis code for HCC capture.
Document the treatment plan: dietary counseling, exercise prescription, medication management, or bariatric surgery evaluation.
When BMI is 40+, query the provider if the assessment only says 'obesity' without specifying 'morbid' or 'severe'.
Document obesity-related comorbidities (sleep apnea, osteoarthritis, GERD) as they support the medical necessity of the obesity diagnosis.
If the patient has had bariatric surgery, document the procedure status and current BMI to determine if morbid obesity is still appropriate.
Common Coding Mistakes
Coding E66.09 (other obesity) instead of E66.01 (morbid obesity) when the BMI is 40+ and the provider documents severe/morbid obesity.
Reporting only the BMI Z-code (Z68.4x) without the clinical obesity diagnosis code, BMI codes alone do not map to HCCs.
Failing to query the provider when the BMI clearly indicates morbid obesity but the documentation only states 'obesity.'
Not recapturing morbid obesity annually, this is a chronic condition that requires documentation at each encounter for risk adjustment.
V24 to V28 Changes
Under V28, morbid obesity maps to HCC 48 (Morbid Obesity), with a community non-dual aged RAF of 0.186. Coders moving from V24 should note that the morbid obesity category was renumbered in the transition, so do not carry an old V24 HCC number forward, confirm the code against the current V28 crosswalk. Only the severe obesity codes feed HCC 48: E66.01, E66.2, and E66.813 (obesity, class 3). The broader obesity codes, including E66.09 (other obesity due to excess calories), E66.1 (drug-induced obesity), E66.8 entries other than class 3, and E66.9 (obesity, unspecified), remain non-payment codes. A documented BMI of 40 or greater alone does not earn HCC 48, the specific morbid or class 3 obesity diagnosis must be present.
Related Conditions
Related references
Sources
RAF weights are community, non-dual, aged base coefficients from the CMS-HCC V28 model (PY2026). Verify against the latest CMS Rate Announcement for payment.
Verified current to CMS-HCC V28, payment year 2026 — last reviewed May 10, 2026.
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