G21
⚠ Non-billable
Secondary parkinsonism
ICD-10-CM · FY2026 · Diseases of the Nervous System
Code
G21
System
ICD-10-CM
Billable
No — use specific code
Effective
FY2026
Chapter
Diseases of the Nervous System
Source
CMS / CDC NCHS
⚠ Verify before billing. Confirm against the current CMS/NCHS ICD-10-CM files and your payer's rules before claims submission.
Official coding notes
From CMS's ICD-10-CM Tabular List.
Excludes1 — never code together
- Huntington's disease (G10)
- neurocognitive disorder with Lewy bodies (G31.83)
- Shy-Drager syndrome (G90.3)
- syphilitic Parkinsonism (A52.19)
Frequently asked questions
What is ICD-10 code G21?
ICD-10-CM code G21 represents Secondary parkinsonism. It is a non-billable header code requiring a more specific subcategory in the Diseases of the Nervous System chapter, effective October 1, 2025 – September 30, 2026.
Is G21 billable?
No. G21 is a non-billable header. Select a more specific subcategory for claims submission.
What chapter is G21 in?
G21 belongs to the Diseases of the Nervous System chapter (G00–G99) of ICD-10-CM.
Related codes in the G21 category
G21.0
Malignant neuroleptic syndrome
Billable
G21.1
Other drug-induced secondary parkinsonism
Non-billable
G21.2
Secondary parkinsonism due to other external agents
Billable
G21.3
Postencephalitic parkinsonism
Billable
G21.4
Vascular parkinsonism
Billable
G21.8
Other secondary parkinsonism
Billable
G21.9
Secondary parkinsonism, unspecified
Billable
G21.11
Neuroleptic induced parkinsonism
Billable
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