Is R40 a billable ICD-10-CM code?

No. R40 is a non-billable header code. Code to a higher level of specificity using one of its child codes.

Where does R40 sit in the tabular list?

Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R99), in the block Symptoms and signs involving cognition, perception, emotional state and behavior (R40-R46).

What cannot be coded together with R40?

R40 carries an Excludes1 note, which means the conditions it lists can never be coded together with it on the same encounter.

R40

R40 — Somnolence, stupor and coma

Non-billable headerICD-10-CM

R40 is a non-billable header ICD-10-CM code for somnolence, stupor and coma. 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.

neonatal coma (P91.5)
somnolence, stupor and coma in diabetes (E08-E13)
somnolence, stupor and coma in hepatic failure (K72.-)
somnolence, stupor and coma in hypoglycemia (nondiabetic) (E15)

Other codes that can never be billed with R40

These codes carry an Excludes1 note pointing at R40. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading R40 alone.

R40.0Somnolence
R40.1Stupor
R41.82Altered mental status, unspecified
R40.2ANontraumatic coma due to underlying condition
R46.4Slowness and poor responsiveness
R55Syncope and collapse
F06.1Catatonic disorder due to known physiological condition
F20.2Catatonic schizophrenia

Risk adjustment

R40 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 R40

5 child codes. Green means billable.

Questions about R40

Is R40 a billable ICD-10-CM code?: No. R40 is a non-billable header code. Code to a higher level of specificity using one of its child codes.
Where does R40 sit in the tabular list?: Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R99), in the block Symptoms and signs involving cognition, perception, emotional state and behavior (R40-R46).
What cannot be coded together with R40?: R40 carries an Excludes1 note, which means the conditions it lists can never be coded together with it on the same encounter.