E66.813
BillableObesity, class 3
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is E66.813 an HCC code?
Yes. E66.813 maps to Morbid Obesity under the CMS-HCC V28 risk adjustment model (and Morbid Obesity under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for E66.813
For E66.813 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed E66.813 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
E66.813 is the ICD-10-CM diagnosis code for obesity, class 3. Class 3 obesity, the most severe level of obesity typically defined as BMI 40 or higher. E66.813 sits in the ICD-10-CM chapter for endocrine, nutritional and metabolic diseases (e00-e89), within the section covering overweight, obesity and other hyperalimentation (e65-e68).
Under the CMS-HCC V28 risk adjustment model, E66.813 maps to Morbid Obesity (HCC 48) with a community, non-dual, aged base RAF weight of 0.226. Under the older V24 model, E66.813 mapped to the same category but with a base RAF weight of 0.250 — V28 recalibrated weights across the entire model. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
Class 3 obesity may also qualify as morbid obesity; review documentation for E66.01 applicability. Because E66.813 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for E66.813 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Class 3 obesity may also qualify as morbid obesity; review documentation for E66.01 applicability
- •Document BMI ≥40 to support this classification
Clinical Significance
Obesity class 3 represents the most severe classification of obesity based on body mass index of 40 or higher. This classification system aligns with World Health Organization standards and carries the same clinical implications as morbid obesity, including dramatically elevated risks of cardiovascular disease, diabetes mellitus, musculoskeletal disorders, and premature mortality. This code provides an alternative to E66.01 for classifying severe obesity.
Documentation Requirements
- ✓Documentation must include a specific body mass index of 40 or higher with a Z68.4x code assigned additionally.
- ✓The provider should document the diagnosis of class 3 or severe obesity explicitly.
- ✓Associated comorbidities, current weight management strategies, and any referrals for bariatric evaluation should be documented.
- ✓The clinical impact of obesity on the patient's overall health status should be noted.