G40.001
BillableLocalization-related (focal) (partial) idiopathic epilepsy and epileptic syndromes with seizures of localized onset, not intractable, with status epilepticus
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is G40.001 an HCC code?
Yes. G40.001 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 G40.001
For G40.001to 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 G40.001 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
G40.001 is the ICD-10-CM diagnosis code for localization-related (focal) (partial) idiopathic epilepsy and epileptic syndromes with seizures of localized onset, not intractable, with status epilepticus. This is a type of epilepsy that starts in a specific area of the brain and causes seizures that are localized to that region. The seizures are not difficult to control with medication, but the patient is currently experiencing status epilepticus, which is a prolonged or repeated seizure emergency. G40.001 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, G40.001 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, G40.001 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.
Verify documentation confirms the seizures are localized/focal in onset and that the patient is experiencing active status epilepticus at the time of coding. Because G40.001 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 G40.001 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify documentation confirms the seizures are localized/focal in onset and that the patient is experiencing active status epilepticus at the time of coding
- •Ensure the 'not intractable' status is documented; if seizures become drug-resistant, this code would change to G40.011 (intractable variant)
Clinical Significance
This code captures focal epilepsy of unknown cause (idiopathic) with localized seizures that are medication-responsive but with the patient currently in status epilepticus. Status epilepticus is a neurological emergency requiring immediate intervention. Accurate coding captures both the chronic epilepsy condition and the acute life-threatening complication.
Documentation Requirements
- ✓Documentation confirming localization-related (focal) epilepsy with seizures of localized onset
- ✓Documentation that the epilepsy is idiopathic (no identified structural or metabolic cause)
- ✓Current episode of status epilepticus documented with onset time and duration
- ✓Documentation that the epilepsy is generally not intractable (responds to medication)
- ✓EEG findings if available showing focal epileptiform activity
- ✓Emergency treatment documentation and response to intervention
Commonly Confused Codes
- •G40.009 — Same epilepsy type, not intractable, WITHOUT status epilepticus; the default non-emergency code
- •G40.011 — Same epilepsy type, intractable, with status epilepticus; different intractability status
- •G40.101 — Symptomatic focal epilepsy with simple partial seizures and status epilepticus; symptomatic (known cause) rather than idiopathic
- •G40.301 — Generalized idiopathic epilepsy with status epilepticus; generalized rather than focal onset
- •G41.0 — Grand mal status epilepticus (ICD-9 equivalent); ensure current ICD-10 code is used