G40.409
BillableOther generalized epilepsy and epileptic syndromes, 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 G40.409 an HCC code?
Yes. G40.409 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 G40.409
For G40.409 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 G40.409 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
G40.409 is the ICD-10-CM diagnosis code for other generalized epilepsy and epileptic syndromes, not intractable, without status epilepticus. A generalized epilepsy of a type other than idiopathic that is controllable with medication, and the patient is not currently in status epilepticus. G40.409 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, G40.409 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, G40.409 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.
Investigate and document the etiology of the 'other' generalized epilepsy for complete clinical documentation. Because G40.409 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 G40.409 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Investigate and document the etiology of the 'other' generalized epilepsy for complete clinical documentation
- •Link this code to any secondary conditions that may have caused the epilepsy
Clinical Significance
Other generalized epilepsy without status epilepticus and not intractable represents a chronic seizure disorder involving both brain hemispheres that is adequately managed with antiepileptic medications. This condition requires ongoing neurological monitoring, medication management, and carries risks of breakthrough seizures that impact patient safety and quality of life.
Documentation Requirements
- ✓Specific type of generalized epilepsy identified (secondary cause such as brain injury, infection, tumor if known)
- ✓Statement confirming seizures respond to medication (not intractable)
- ✓Confirmation that status epilepticus is NOT present at the encounter
- ✓Current antiepileptic medication regimen and adherence
- ✓Seizure frequency and most recent seizure date
- ✓Any relevant EEG or neuroimaging findings
Commonly Confused Codes
- •G40.401 — Same epilepsy type but WITH status epilepticus; requires documentation of prolonged seizure activity
- •G40.419 — Same epilepsy type without status epilepticus but INTRACTABLE; requires documentation of drug resistance
- •G40.309 — Generalized IDIOPATHIC epilepsy without status epilepticus; use when no secondary cause identified
- •G40.909 — Epilepsy UNSPECIFIED; avoid this less specific code when documentation supports 'other generalized' type
- •R56.9 — Unspecified convulsions; use only for single seizure events without established epilepsy diagnosis