2026 ICD-10-CM Diagnosis Code G20.A1Parkinson's disease without dyskinesia, without mention of fluctuations

ICD-10-CM Codes›G00–G99›G20-G26›G20

ICD-10-CM G20.A1
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

G20.A1 is a billable ICD-10-CM diagnosis code for Parkinson's disease without dyskinesia, without mention of fluctuations. 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.A1
Billable Status
Yes — Valid for Submission
Code Describes
Parkinson's disease without dyskinesia, without mention of fluctuations
Short Description
Parkinson's dis w/o dyskinesia, w/o mention of fluctuations
Parent Code
G20.A
Parkinson's disease without dyskinesia

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG20-G26Extrapyramidal and movement disorders
CategoryG20Parkinson's disease
This CodeG20.A1Parkinson's disease without dyskinesia, without mention of fluctuations

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Autonomic disorder due to Parkinson disease
  • Autosomal dominant late onset Parkinson disease
  • Autosomal recessive familial Parkinson disease
  • Cerebral degeneration due to Parkinson's disease
  • Dementia associated with Parkinson's Disease
  • Dementia due to Parkinson's disease
  • Fluency disorder due to Parkinson disease
  • Juvenile Parkinson's disease
  • Parkinson's disease
  • Parkinson's facies
  • Psychosis co-occurrent and due to Parkinson's disease
  • Restrictive lung disease
  • Restrictive lung disease due to Parkinson disease
  • Young onset Parkinson disease

Tabular List NotesGuidance

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

Inclusion Terms

  • Parkinson's disease NOS
  • Parkinson's disease without dyskinesia, without mention of OFF episodes

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
        • Parkinson's disease
    • Dementia(degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety)
      • with
        • Parkinson's disease
          • with behavioral disturbance
    • Dementia(degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety)
      • in (due to)
        • Parkinson's disease
    • Disease, diseased
      • Parkinson's
    • Disease, diseased
      • Parkinson's
        • without dyskinesia
          • without mention of
            • fluctuations
    • Disease, diseased
      • Parkinson's
        • without dyskinesia
          • without mention of
            • OFF episodes

Clinical ClassificationClinical

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

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

Clinical InformationClinical

  • Restrictive Lung Disease

    decreased lung volume and inadequate ventilation due to parenchymal lung disorders (e.g., interstitial pulmonary fibrosis) or extrapulmonary disorders (e.g., scoliosis). patients present with shortness of breath and cough.

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.A1 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.A1Overview

Is G20.A1 (Parkinson's disease without dyskinesia) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report Parkinson's disease without dyskinesia, without mention of fluctuations 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.