ICD-10-CM 2027 diagnosis code

G99Other disorders of nervous system in diseases classified elsewhere

Not billable — use a more specific code

G99 is a header code, so it can't be reported by itself. Choose one of the 3 more specific codes beneath it.Short description: Oth disorders of nervous system in diseases classd elswhr

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About G99

G99 is the ICD-10-CM diagnosis code for other disorders of nervous system in diseases classified elsewhere. It belongs to block G89-G99 (other disorders of the nervous system) and chapter 6 (diseases of the nervous system). It is a header code, so it can't be reported by itself; one of its 3 subcodes must be used instead.

To report this condition, pick the subcode that matches the documentation: G99.0 (elsewhere), G99.2 (elsewhere) and G99.8 (elsewhere).

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Specific codes under G99

Notes that apply from higher levels

Instructions written at a parent level also apply to G99.

Broader instructions also apply from Chapter 6: Diseases of the nervous system.

Code history

2016
2017
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2019
2020
2021
2022
2023
2024
2025
2026
2027

FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
No changes since FY2016.

Common questions about G99

Is G99 billable?: No. G99 is a header code. Report one of its more specific subcodes instead.