Is G40 a billable ICD-10-CM code?

No. G40 is a non-billable header code. Code to a higher level of specificity using one of its child codes.

Where does G40 sit in the tabular list?

Diseases of the nervous system (G00-G99), in the block Episodic and paroxysmal disorders (G40-G47).

What cannot be coded together with G40?

G40 carries an Excludes1 note, which means the conditions it lists can never be coded together with it on the same encounter.

G40

G40 — Epilepsy and recurrent seizures

Non-billable headerICD-10-CM

G40 is a non-billable header ICD-10-CM code for epilepsy and recurrent seizures. It cannot be billed on its own: choose one of the more specific child codes below.

Excludes1 — never code together

These conditions cannot occur together. Billing both on the same encounter is a denial.

conversion disorder with seizures (F44.5)
convulsions NOS (R56.9)
post traumatic seizures (R56.1)
seizure (convulsive) NOS (R56.9)
seizure of newborn (P90)

Excludes2 — not included here, but may coexist

The excluded condition is not part of this code, but a patient can have both. You may code both.

hippocampal sclerosis (G93.81)
mesial temporal sclerosis (G93.81)
temporal sclerosis (G93.81)
Todd's paralysis (G83.84)

Notes

Additional guidance from the ICD-10-CM tabular list.

the following terms are to be considered equivalent to intractable: pharmacoresistant (pharmacologically resistant), treatment resistant, refractory (medically) and poorly controlled

Other codes that can never be billed with G40

These codes carry an Excludes1 note pointing at G40. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading G40 alone.

P90Convulsions of newborn
R56Convulsions, not elsewhere classified
R56.01Complex febrile convulsions
R56.1Post traumatic seizures
G40.89Other seizures
G25.3Myoclonus
G40.0Localization-related (focal) (partial) idiopathic epilepsy and epileptic syndromes with seizures of localized onset

Risk adjustment

G40 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.

Code to one of these instead G40

11 child codes. Green means billable.

Questions about G40

Is G40 a billable ICD-10-CM code?: No. G40 is a non-billable header code. Code to a higher level of specificity using one of its child codes.
Where does G40 sit in the tabular list?: Diseases of the nervous system (G00-G99), in the block Episodic and paroxysmal disorders (G40-G47).
What cannot be coded together with G40?: G40 carries an Excludes1 note, which means the conditions it lists can never be coded together with it on the same encounter.