G40.A09
BillableAbsence epileptic syndrome, 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.A09 an HCC code?
Yes. G40.A09 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.A09
For G40.A09to 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.A09 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
G40.A09 is the ICD-10-CM diagnosis code for absence epileptic syndrome, not intractable, without status epilepticus. Absence epilepsy (characterized by brief lapses in consciousness) that responds to medication, without current status epilepticus. G40.A09 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.A09 maps to Seizure Disorders and Convulsions (HCC 201) with a community, non-dual, aged base RAF weight of 0.245. Under the older V24 model, G40.A09 mapped to the same category but with a base RAF weight of 0.220 — 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.
Absence epilepsy is more common in children and typically has a good prognosis with medication. Because G40.A09 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.A09 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Absence epilepsy is more common in children and typically has a good prognosis with medication
- •Document the frequency and duration of absence episodes for clinical clarity
Clinical Significance
Absence epileptic syndrome, controlled and without status epilepticus, is a common childhood epilepsy characterized by brief staring spells lasting 5-30 seconds with abrupt onset and offset. This syndrome has a generally favorable prognosis with many children outgrowing seizures by adolescence. Proper identification is important for school accommodations and driving restrictions.
Documentation Requirements
- ✓Confirmed absence epilepsy diagnosis
- ✓EEG findings showing generalized spike-and-wave discharges
- ✓Seizure control documentation (not intractable)
- ✓Absence of status epilepticus
- ✓Seizure frequency and school impact
- ✓Current medication regimen and compliance
Commonly Confused Codes
- •G40.A01 — Absence epilepsy WITH status epilepticus
- •G40.A19 — Absence epilepsy, INTRACTABLE, without status epilepticus
- •G40.B09 — Juvenile myoclonic epilepsy; may coexist with absence seizures but is a different syndrome
- •G40.909 — Unspecified epilepsy; less specific when absence type is documented
- •R55 — Syncope; may mimic absence seizures clinically