G40.821
BillableEpileptic spasms, 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 G40.821 an HCC code?
Yes. G40.821 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 G40.821
For G40.821 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 G40.821 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
G40.821 is the ICD-10-CM diagnosis code for epileptic spasms, not intractable, with status epilepticus. Epileptic spasms that can be controlled with medication, currently experiencing a prolonged seizure state (status epilepticus). G40.821 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, G40.821 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, G40.821 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 both the spasm type and active status epilepticus to justify this specific code. Because G40.821 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 G40.821 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify documentation confirms both the spasm type and active status epilepticus to justify this specific code
- •Distinguish from G40.822 by confirming the patient is currently in or recently experienced status epilepticus
Clinical Significance
Epileptic spasms (formerly infantile spasms or West syndrome) with status epilepticus represent a severe seizure type characterized by sudden flexion or extension movements, often occurring in clusters. When presenting with status epilepticus, this is a neurological emergency. Epileptic spasms are a hallmark of early-life epileptic encephalopathies and carry significant risk of developmental regression.
Documentation Requirements
- ✓Documentation of epileptic spasms (flexor, extensor, or mixed type)
- ✓Active status epilepticus during the encounter
- ✓Statement that spasms respond to treatment (not intractable)
- ✓EEG findings (hypsarrhythmia if infantile spasms)
- ✓Age of onset and developmental assessment
- ✓Treatment provided including ACTH, vigabatrin, or other first-line agents
Commonly Confused Codes
- •G40.822 — Epileptic spasms, not intractable, WITHOUT status epilepticus
- •G40.823 — Epileptic spasms, INTRACTABLE, with status epilepticus
- •G40.811 — Lennox-Gastaut with status epilepticus; LGS may evolve from spasms but is distinct
- •G40.42 — CDKL5 Deficiency Disorder; may present with spasms but has specific genetic code
- •R25.8 — Other abnormal involuntary movements; non-epileptic movement disorders