Is H40 a billable ICD-10-CM code?

No. H40 is a non-billable header code. Code to a higher level of specificity using one of its child codes.

Where does H40 sit in the tabular list?

Diseases of the eye and adnexa (H00-H59), in the block Glaucoma (H40-H42).

What cannot be coded together with H40?

H40 carries an Excludes1 note, which means the conditions it lists can never be coded together with it on the same encounter.

H40

H40 — Glaucoma

Non-billable headerICD-10-CM

H40 is a non-billable header ICD-10-CM code for glaucoma. 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.

absolute glaucoma (H44.51-)
congenital glaucoma (Q15.0)
traumatic glaucoma due to birth injury (P15.3)

Other codes that can never be billed with H40

These codes carry an Excludes1 note pointing at H40. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading H40 alone.

H40.2Primary angle-closure glaucoma
H42Glaucoma in diseases classified elsewhere

Risk adjustment

H40 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 H40

9 child codes. Green means billable.

Questions about H40

Is H40 a billable ICD-10-CM code?: No. H40 is a non-billable header code. Code to a higher level of specificity using one of its child codes.
Where does H40 sit in the tabular list?: Diseases of the eye and adnexa (H00-H59), in the block Glaucoma (H40-H42).
What cannot be coded together with H40?: H40 carries an Excludes1 note, which means the conditions it lists can never be coded together with it on the same encounter.