2026 ICD-10-CM Diagnosis Code G20.CParkinsonism, unspecified

ICD-10-CM Codes›G00–G99›G20-G26›G20

ICD-10-CM G20.C
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

G20.C is a billable ICD-10-CM diagnosis code for parkinsonism, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Parkinson`s disease.

Code Identity

ICD-10-CM Code
G20.C
Billable Status
Yes — Valid for Submission
Code Describes
Parkinsonism, unspecified
Short Description
Parkinsonism, unspecified
Same as the full description in the CMS dataset.
Parent Code
G20
Parkinson's disease

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG20-G26Extrapyramidal and movement disorders
CategoryG20Parkinson's disease
This CodeG20.CParkinsonism, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Adult-onset dystonia parkinsonism
  • Amyotrophic lateral sclerosis with dementia
  • Amyotrophic lateral sclerosis with parkinsonism
  • Amyotrophic lateral sclerosis, parkinsonism, dementia complex
  • Amyotrophic lateral sclerosis, parkinsonism, dementia complex of Kii Peninsula
  • Amyotrophic lateral sclerosis, parkinsonism, dementia complex of West New Guinea
  • Atypical juvenile parkinsonism
  • Atypical Parkinsonism
  • Dissociative neurological symptom disorder co-occurrent with parkinsonism
  • Dopamine transporter deficiency syndrome
  • Early onset parkinsonism and intellectual disability syndrome
  • Frontotemporal dementia with parkinsonism-17
  • Functional parkinsonism
  • Hemiparkinsonism hemiatrophy syndrome
  • Hypokinetic parkinsonian dysphonia
  • Parkinsonian facies
  • Parkinsonian pyramidal syndrome
  • Parkinsonian tremor
  • Parkinsonism
  • Parkinsonism due to heredodegenerative disorder
  • Parkinsonism with polyneuropathy
  • Parkinson's disease
  • Perry syndrome
  • Rapid onset dystonia parkinsonism
  • Symptomatic parkinsonism
  • X-linked dystonia parkinsonism
  • X-linked parkinsonism with spasticity syndrome
  • Young onset Parkinson disease

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Parkinsonism, NOS

Type 1 Excludes

  • Parkinson's disease NOS G20.A1
  • Parkinson's disease with dyskinesia G20.B
  • Parkinson's disease without dyskinesia G20.A
  • secondary parkinsonism G21

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Dementia(degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety)
      • with
        • Parkinsonism
    • Dementia(degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety)
      • with
        • Parkinsonism
          • with behavioral disturbance
    • Dementia(degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety)
      • in (due to)
        • paralysis agitans
    • Dementia(degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety)
      • in (due to)
        • paralysis agitans
          • with behavioral disturbance
    • Hemiparkinsonism
    • Paralysis, paralytic(complete) (incomplete)
      • agitans
    • Parkinsonism(idiopathic) (primary)
    • Parkinsonism(idiopathic) (primary)
      • dementia
    • Parkinsonism(idiopathic) (primary)
      • dementia
        • with behavioral disturbance
    • Pyramidopallidonigral syndrome
    • Syndrome
      • pyramidopallidonigral

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NVS004
Parkinson`s disease
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Parkinson's Disease

Parkinson's disease (PD) is a type of movement disorder. It happens when nerve cells in the brain don't produce enough of a brain chemical called dopamine. Sometimes it is genetic, but most cases do not seem to run in families. Exposure to chemicals in the environment might play a role.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Code History & ChangesHistory

Replacement G20.C replaces the following previously assigned code(s):

  • G20 - Parkinson's disease
FY 2024AddedAdded to the ICD-10-CM code setEffective October 1, 2023.
FY 2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About G20.COverview

Is G20.C (Parkinson's disease) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report parkinsonism, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.