T32.91
BillableCorrosions involving 90% or more of body surface with 10-19% third degree corrosion
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is T32.91 an HCC code?
Yes. T32.91 maps to Severe Skin Burn or Condition under the CMS-HCC V28 risk adjustment model (and Severe Skin Burn or Condition 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 T32.91
For T32.91 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 T32.91 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
T32.91 is the ICD-10-CM diagnosis code for corrosions involving 90% or more of body surface with 10-19% third degree corrosion. Catastrophic chemical burn covering 90% or more of the body with 10-19% of the area showing the deepest, most severe burns. This is a life-threatening injury with extensive body involvement. T32.91 sits in the ICD-10-CM chapter for injury, poisoning and certain other consequences of external causes (s00-t88), within the section covering burns and corrosions of multiple and unspecified body regions (t30-t32).
Under the CMS-HCC V28 risk adjustment model, T32.91 maps to Severe Skin Burn or Condition (HCC 385) with a community, non-dual, aged base RAF weight of 0.350. Under the older V24 model, T32.91 mapped to the same category but with a base RAF weight of 0.517 — 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.
Document the specific chemical agent involved and the circumstances of exposure for complete medical record. Because T32.91 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 T32.91 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Document the specific chemical agent involved and the circumstances of exposure for complete medical record
- •Ensure seventh character is included and verify that the percentages documented support both the total body surface area and third-degree extent
Clinical Significance
This represents catastrophic chemical burns covering 90% or more of the body with moderate deep tissue involvement (10-19% third-degree), indicating potentially fatal injury with extremely high mortality risk. These patients require immediate burn center intervention with intensive medical care and extensive surgical management, representing the most severe category of chemical burn injury.
Documentation Requirements
- ✓Total body surface area (90% or greater)
- ✓Third-degree burn percentage (10-19%)
- ✓Chemical agent identification
- ✓Exposure circumstances and timeline
- ✓Current treatment phase
- ✓Anatomical distribution
- ✓Associated systemic complications
- ✓Surgical procedures and prognosis