G40.812
BillableLennox-Gastaut syndrome, not intractable, without status epilepticus
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is G40.812 an HCC code?
Yes. G40.812 maps to Seizure Disorders and Convulsions under the CMS-HCC V28 risk adjustment model (and Seizure Disorders and Convulsions 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 G40.812
For G40.812 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 G40.812 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
G40.812 is the ICD-10-CM diagnosis code for lennox-gastaut syndrome, not intractable, without status epilepticus. Lennox-Gastaut syndrome, a severe childhood epilepsy with multiple seizure types that can be controlled with medication, not currently in a prolonged seizure state. G40.812 sits in the ICD-10-CM chapter for diseases of the nervous system (g00-g99), within the section covering episodic and paroxysmal disorders (g40-g47).
Under the CMS-HCC V28 risk adjustment model, G40.812 maps to Seizure Disorders and Convulsions (HCC 201) with a community, non-dual, aged base RAF weight of 0.262. Under the older V24 model, G40.812 mapped to the same category but with a base RAF weight of 0.244 — 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.
This syndrome typically presents in early childhood with developmental delay and multiple seizure types. Because G40.812 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 G40.812 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This syndrome typically presents in early childhood with developmental delay and multiple seizure types
- •Document the specific seizure types observed (tonic, atonic, absence) to support the diagnosis
Clinical Significance
Lennox-Gastaut syndrome without status epilepticus and not intractable represents a rare presentation where this severe epilepsy syndrome is adequately controlled with medication. LGS typically involves multiple seizure types, characteristic EEG patterns, and cognitive impairment. Even when seizures are controlled, these patients require ongoing comprehensive care for developmental and neurological needs.
Documentation Requirements
- ✓Confirmed Lennox-Gastaut syndrome diagnosis
- ✓Documentation of seizure types (tonic, atonic, atypical absence)
- ✓EEG findings showing slow spike-and-wave pattern
- ✓Confirmation seizures are controlled (not intractable)
- ✓Absence of status epilepticus at the encounter
- ✓Cognitive and developmental assessment
- ✓Current medication regimen with response documentation
Commonly Confused Codes
- •G40.811 — LGS, not intractable, WITH status epilepticus
- •G40.814 — LGS, INTRACTABLE, without status epilepticus; more common presentation
- •G40.822 — Epileptic spasms without status epilepticus; distinct from LGS
- •G40.802 — Other epilepsy without status epilepticus; less specific
- •G40.409 — Other generalized epilepsy; use when LGS criteria not met