G40.909 ICD-10-CM Code: Epilepsy, unspecified, not intractable, without status epilepticus
HCC Buddy Code Card
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FY 2026 Apr update / Diseases of the nervous system (G00-G99) / Episodic and paroxysmal disorders (G40-G47)
G40.909
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceEpilepsy, unspecified, not intractable, without status epilepticus
Epilepsy of unknown type that responds to medication, without current status epilepticus.
Buddy Insight
Epilepsy, unspecified, not intractable, without status epilepticus is the most commonly used unspecified epilepsy code.
CMS-HCC V28
MappedHCC 201
RAF 0.262
CMS-HCC V24
MappedHCC 79
RAF 0.244
ACA/HHS
00
RAF 0
ESRD/PACE
MappedHCC 79
RAF 0.0
RXHCC
MappedHCC 164
RAF 0.0
Code Trumping
Basket needed
Code Book Path
Inclusion Terms
Official- Epilepsy NOS
- Epileptic convulsions NOS
- Epileptic fits NOS
- Epileptic seizures NOS
- Recurrent seizures NOS
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for G40.909 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for G40.909 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for G40.909 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for G40.909 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for G40.909 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for G40.909 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.
Is G40.909 an HCC code?
Yes. G40.909 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 G40.909
For G40.909to 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 G40.909 during that encounter, not just copy-forwarded from a problem list.
What This Code Means
G40.909 is the ICD-10-CM diagnosis code for epilepsy, unspecified, not intractable, without status epilepticus. Epilepsy of unknown type that responds to medication, without current status epilepticus. G40.909 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, G40.909 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, G40.909 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 is the most common code for unspecified epilepsy in patients whose seizures are controlled. Because G40.909 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 G40.909 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This is the most common code for unspecified epilepsy in patients whose seizures are controlled
- •Verify that the patient's seizures are indeed controlled by medication before assigning 'not intractable'
Clinical Significance
Epilepsy, unspecified, not intractable, without status epilepticus is the most commonly used unspecified epilepsy code. It captures patients with a diagnosed epilepsy disorder that is medication-controlled but whose specific epilepsy type is not documented. While it maps to the same HCC, striving for greater specificity improves clinical documentation quality and supports care management.
Documentation Requirements
- ✓Diagnosis of epilepsy by a provider
- ✓Confirmation seizures are controlled with medication
- ✓Absence of status epilepticus
- ✓Current antiepileptic medication regimen
- ✓Seizure frequency and last known seizure
- ✓Monitoring plan (EEG, drug levels, follow-up schedule)
Commonly Confused Codes
- •G40.901 — Unspecified epilepsy WITH status epilepticus
- •G40.919 — Unspecified epilepsy, INTRACTABLE, without status epilepticus
- •G40.409 — Other generalized epilepsy; more specific if generalized type is known
- •G40.802 — Other epilepsy, not intractable; for epilepsy that is classified but not elsewhere specified
- •R56.9 — Unspecified convulsions; no established epilepsy diagnosis