G40.311
BillableGeneralized idiopathic epilepsy and epileptic syndromes, intractable, with status epilepticus
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is G40.311 an HCC code?
Yes. G40.311 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 G40.311
For G40.311 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 G40.311 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
G40.311 is the ICD-10-CM diagnosis code for generalized idiopathic epilepsy and epileptic syndromes, intractable, with status epilepticus. A generalized epilepsy that affects the entire brain from the start and is difficult to control with medication, and the patient is currently experiencing status epilepticus. G40.311 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, G40.311 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, G40.311 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.
The '1' in the fifth character indicates status epilepticus, which is a medical emergency requiring intensive care. Because G40.311 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 G40.311 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •The '1' in the fifth character indicates status epilepticus, which is a medical emergency requiring intensive care
- •Clearly document failed medication trials to support the intractable diagnosis in the medical record
Clinical Significance
This code captures the most severe form of generalized idiopathic epilepsy — drug-resistant and in active status epilepticus. It represents a neurological emergency with the highest morbidity and mortality risk among the generalized epilepsy codes. These patients require ICU-level care and may need aggressive interventions including anesthetic infusions to terminate seizures.
Documentation Requirements
- ✓Documentation of generalized idiopathic epilepsy (bilateral onset, no identified cause)
- ✓Evidence of intractable status with documented medication failure history
- ✓Active status epilepticus with onset time, type, duration, and emergency interventions
- ✓Documentation of failed antiepileptic medications (at least 2 adequate trials)
- ✓EEG monitoring documentation for ongoing seizure activity assessment
- ✓ICU admission and treatment escalation documentation