ICD-10-CM 2027 diagnosis code

G20.AParkinson's disease without dyskinesia

Not billable — use a more specific code

G20.A is a header code, so it can't be reported by itself. Choose one of the 2 more specific codes beneath it.

Code last changed in FY2024 (effective October 1, 2023). Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About G20.A

G20.A is the ICD-10-CM diagnosis code for Parkinson's disease without dyskinesia. It belongs to category G20 (Parkinson's disease), block G20-G26 (extrapyramidal and movement disorders) and chapter 6 (diseases of the nervous system). It is a header code, so it can't be reported by itself; one of its 2 subcodes must be used instead.

Within G20, choose G20.A (without dyskinesia) only when documentation doesn't support a more specific option: with dyskinesia (G20.B) and parkinsonism, unspecified (G20.C).

To report this condition, pick the subcode that matches the documentation: G20.A1 (without mention of fluctuations) and G20.A2 (with fluctuations).

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 was added in FY2024, effective October 1, 2023.

Specific codes under G20.A

Notes that apply from higher levels

Instructions written at a parent level also apply to G20.A.

› From G20 Parkinson's disease

Use additional code

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)
mild neurocognitive disorder due to known physiological condition (F06.7-)

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

Codes whose notes reference G20.A

G20.CExcludes1

Code history

2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027

FY2024 (effective 10/1/2023): Added
No changes since FY2024.

Common questions about G20.A

Is G20.A billable?: No. G20.A is a header code. Report one of its more specific subcodes instead.