ICD-10-CM 2027
ICD-10 code for Parkinson's disease
From the official ICD-10-CM alphabetic index entry “Disease, diseased › Parkinson's”. Page updated September 29, 2026.
About coding Parkinson's disease
The ICD-10-CM code for Parkinson's disease is G20.A1 (Parkinson's disease without dyskinesia, without mention of fluctuations). The official index lists 8 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on G20.A1.
Within G20.A, choose G20.A1 (without mention of fluctuations) only when documentation doesn't support a more specific option: with fluctuations (G20.A2).
Use an additional code, if applicable, to identify: dementia with anxiety (F02.84, F02.A4, F02.B4, F02.C4), dementia with behavioral disturbance (F02.81-, F02.A1-, F02.B1-, F02.C1-), dementia with mood disturbance (F02.83, F02.A3, F02.B3, F02.C3), dementia with psychotic disturbance (F02.82, F02.A2, F02.B2, F02.C2), dementia without behavioral disturbance (F02.80, F02.A0, F02.B0, F02.C0) and 1 more.
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
More specific Parkinson's disease codes (official index)
- with dyskinesia
- with
- fluctuations G20.B2 — Parkinson's disease with dyskinesia, with fluctuations
- OFF episodes G20.B2 — Parkinson's disease with dyskinesia, with fluctuations
- without mention of
- fluctuations G20.B1 — Parkinson's disease with dyskinesia, without mention of fluctuations
- OFF episodes G20.B1 — Parkinson's disease with dyskinesia, without mention of fluctuations
- without dyskinesia
- with
- fluctuations G20.A2 — Parkinson's disease without dyskinesia, with fluctuations
- OFF episodes G20.A2 — Parkinson's disease without dyskinesia, with fluctuations
- without mention of
- fluctuations G20.A1 — Parkinson's disease without dyskinesia, without mention of fluctuations
- OFF episodes G20.A1 — Parkinson's disease without dyskinesia, without mention of fluctuations
Common questions about Parkinson's disease ICD-10 codes
What is the ICD-10 code for Parkinson's disease?
- G20.A1 — Parkinson's disease without dyskinesia, without mention of fluctuations. More specific codes apply when the documentation supports them: G20.B2, G20.B2, G20.B1, G20.B1 and others below.
Is G20.A1 billable?
- Yes. G20.A1 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can G20.A1 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict G20.A1 as a principal diagnosis.
Is G20.A1 a CC or MCC?
- No. G20.A1 is neither a CC nor an MCC under MS-DRG v44.0.