G40.89
BillableOther seizures
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is G40.89 an HCC code?
Yes. G40.89 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 G40.89
For G40.89 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 G40.89 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
G40.89 is the ICD-10-CM diagnosis code for other seizures. A seizure disorder that doesn't fit into other specific epilepsy categories, characterized by recurrent seizures of various types. G40.89 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, G40.89 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, G40.89 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.
Use this code only when the seizure type cannot be classified into more specific epilepsy categories. Because G40.89 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 G40.89 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code only when the seizure type cannot be classified into more specific epilepsy categories
- •Document the seizure characteristics and frequency to support medical necessity
Clinical Significance
Other seizures is a residual code for seizure disorders that do not fit into specific epilepsy categories. This may include recurrent provoked seizures, seizures of undetermined type, or atypical presentations. This code captures patients with seizure activity that requires monitoring and treatment but does not meet the diagnostic criteria for a specific epilepsy syndrome.
Documentation Requirements
- ✓Description of seizure type and characteristics
- ✓Explanation of why seizures do not fit specific epilepsy syndrome criteria
- ✓Seizure frequency and duration
- ✓Any precipitating factors or triggers
- ✓Diagnostic workup results (EEG, MRI, labs)
- ✓Current treatment and management plan
Excludes 1 — Do NOT code together
Commonly Confused Codes
- •R56.9 — Unspecified convulsions; for single seizure events without recurrence pattern
- •G40.909 — Epilepsy, unspecified; use when epilepsy IS diagnosed but type is unknown
- •G40.802 — Other epilepsy, not intractable; for classified epilepsy not elsewhere specified
- •R56.1 — Post-traumatic seizures; specific to post-injury seizures
- •G40.509 — Epileptic seizures related to external causes; when external trigger is identified