ICD-10 Code G40.309 – Generalized idiopathic epilepsy and epileptic syndromes, not intractable, without status epilepticus (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G40.309 – Generalized idiopathic epilepsy and epileptic syndromes, not intractable, without status epilepticus
What it is
This code identifies generalized idiopathic epilepsy or a related epileptic syndrome that is not intractable and is not accompanied by status epilepticus. Use it when the documentation describes a generalized epilepsy pattern without refractory disease.
Clinical signs
Clinical features vary; refer to documentation. Generalized epilepsies typically involve seizures that affect both sides of the brain from onset, and records may note absence, myoclonic, or generalized tonic-clonic events.
When to use this code
Use this code when the provider documents generalized idiopathic epilepsy or a generalized epileptic syndrome and explicitly states it is not intractable. It also fits when status epilepticus is not present.
Apply it for confirmed epilepsy diagnoses in outpatient, inpatient, or problem-list documentation. If the note only says “seizure” or the epilepsy type is unclear, check documentation before coding.
Do not use for
Do not use this code for intractable epilepsy, status epilepticus, or focal/localized seizure disorders. If the chart documents a different epilepsy syndrome, code that condition instead.
Coding tip
Verify both qualifiers—“not intractable” and “without status epilepticus”—in the provider note before assigning G40.309.