G40.109 ICD-10-CM Code: Localization-related (focal) (partial) symptomatic epilepsy and epileptic syndromes with simple partial seizures, not intractable, without status epilepticus
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FY 2026 Apr update / Diseases of the nervous system (G00-G99) / Episodic and paroxysmal disorders (G40-G47)
G40.109
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceLocalization-related (focal) (partial) symptomatic epilepsy and epileptic syndromes with simple partial seizures, not intractable, without status epilepticus
A type of epilepsy caused by a known brain condition with simple partial seizures that responds to medication, without current prolonged seizure activity.
Buddy Insight
This code represents the stable baseline state of symptomatic focal epilepsy with simple partial seizures — the condition is controlled with medication and the patient is not in status epilepticus.
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- Localization-related (focal) (partial) symptomatic epilepsy and epileptic syndromes with simple partial seizures NOS
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for G40.109 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for G40.109 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for G40.109 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for G40.109 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for G40.109 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for G40.109 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 G40.109 an HCC code?
Yes. G40.109 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 G40.109
For G40.109to 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 G40.109 during that encounter, not just copy-forwarded from a problem list.
What This Code Means
G40.109 is the ICD-10-CM diagnosis code for localization-related (focal) (partial) symptomatic epilepsy and epileptic syndromes with simple partial seizures, not intractable, without status epilepticus. A type of epilepsy caused by a known brain condition with simple partial seizures that responds to medication, without current prolonged seizure activity. G40.109 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, G40.109 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, G40.109 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 '10' indicates symptomatic with simple partial seizures; the final '9' indicates no status epilepticus. Because G40.109 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 G40.109 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •The '10' indicates symptomatic with simple partial seizures; the final '9' indicates no status epilepticus
- •Document the underlying etiology and confirm the seizures are controlled or not currently in status epilepticus
Clinical Significance
This code represents the stable baseline state of symptomatic focal epilepsy with simple partial seizures — the condition is controlled with medication and the patient is not in status epilepticus. Simple partial seizures preserve consciousness, distinguishing them from complex partial seizures. The symptomatic designation indicates an identifiable underlying cause that should also be coded.
Documentation Requirements
- ✓Documentation of focal epilepsy with an identified underlying cause
- ✓Description of simple partial seizure semiology (motor, sensory, autonomic, or psychic symptoms without loss of consciousness)
- ✓Current antiepileptic medication regimen and seizure control status
- ✓Identification of the underlying etiology (stroke, tumor, cortical dysplasia, etc.)
- ✓Seizure frequency and last seizure date if documented
- ✓Confirmation that seizures are NOT intractable and patient is NOT in status epilepticus
Commonly Confused Codes
- •G40.209 — Symptomatic focal epilepsy with COMPLEX partial seizures; impaired awareness differentiates
- •G40.009 — IDIOPATHIC focal epilepsy; no identified cause
- •G40.101 — Same type WITH status epilepticus; acute emergency
- •G40.119 — Same type, intractable; drug-resistant form
- •G40.909 — Epilepsy unspecified; too nonspecific when seizure type and etiology are known