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G20.A2 ICD-10-CM Code: Parkinson's disease without dyskinesia, with fluctuations

Compare with another codeCheck this code on a claim

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Tabular directives
1 inclusion term · 7 use-additional codes
Risk adjustment
CMS-HCC V28: 1 category · CMS-HCC V22 category 78 · RxHCC V08 category 161

Billable · FY2027A valid, specific ICD-10-CM code, reportable for dates of service in FY2027.

What you need to know

Source: CMS/NCHS Official ICD-10-CM tabular notes, quoted. From the CMS/NCHS tabular list for the release in force. A note the category or block publishes applies to this code too; the Instructions section marks which is which.

Use additional codeReport with this code when documented

+3 more in Instructions

IncludesWhat this code covers
  • Parkinson's disease without dyskinesia, with OFF episodes

Most relevant related codes MedCoder-derived

Read off the official notes above and this code’s own position in the tabular list. Which to report is a documentation question; Compare shows the two side by side.

CompareCheck ClaimView Related Codes

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v44, Appendix B.

  • MS-DRG 056 — DEGENERATIVE NERVOUS SYSTEM DISORDERS WITH MCC (MDC 01)
  • MS-DRG 057 — DEGENERATIVE NERVOUS SYSTEM DISORDERS WITHOUT MCC (MDC 01)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Risk Adjustment (CMS-HCC)

Payment categories this diagnosis maps to under CMS-HCC V28, payment year 2026.

  • HCC 199 — Parkinson and Other Degenerative Disease of Basal Ganglia

Other models: CMS-HCC V22 HCC 78 · RxHCC V08 HCC 161

Risk scores depend on the enrollee's full accepted diagnosis set and segment; a category mapping alone does not determine payment.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for G20.A2 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Trace:FY2027 changesChange historyRelease, file and checksum

Notes without a marker are published on G20.A2 itself; “inherited from” names the category or block whose note applies here.

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Parkinson's disease without dyskinesia, with OFF episodes

Use Additional Code

Supplementary codes the tabular list directs you to add.

Source: inherited from G20

Coder workflow for G20.A2

MedCoder structured workflow — derived from this code’s own official record

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
The associated condition or complication
Whether the associated condition the title names is documented; the “with” convention presumes some links, and a provider statement that the conditions are unrelated defeats it (Guidelines I.A.15).
The conditions the Use Additional Code note names
Reported with this code when documented; a conditional instruction (“if applicable”, “if known”) applies only when the record supports it.

Official instructions as workflow

  • Use Additional Code — after identifying G20.A2(7 notes)

    Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with G20.A2 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

    ReviewF02.84, F02.A4, F02.B4, F02.C4, F02.81, F02.A1

    See the official tabular notes · Guidelines I.A.13

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: A condition the Use Additional Code note names is documented.

Coding question: Is a second code reported with G20.A2?

Path: Review the Use Additional Code note and the code it names.

Reason: The additional code is reported when the record documents the condition; a conditional instruction applies only when its condition is met (Guidelines I.A.13).

ReviewF02.84, F02.A4, F02.B4, F02.C4, F02.81, F02.A1

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Coding context

Guidelines, coding notes, decision aids, relationships (with MS-DRG and CCSR classification), hierarchy, HCC, coverage and the context map: what a coder reaches for after the core. Each section names whether it is official source data, a MedCoder-derived relationship or MedCoder editorial.

Code Overview

Parkinson's disease without dyskinesia, with fluctuations is a billable ICD-10-CM diagnosis code (G20.A2).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Verify Before Coding

  • No Medicare Code Editor or MS-DRG Definitions Manual restrictions apply to this code.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder-derived relationships — computed from published CMS and AHRQ datasets

Other codes that name G20.A2 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 2 Excludes1 notes across 2 chapters: G20.C — Parkinsonism, unspecified (via G20.A.-), R25 — Abnormal involuntary movements (via G20.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 1 Excludes2 note: F98.4 — Stereotyped movement disorders (via G20.-).

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

Referenced by 3 Code First instructions across 2 chapters: F02 — Dementia in other diseases classified elsewhere (via G20.-), F06.7 — Mild neurocognitive disorder due to known physiological condition (via G20.-), R47.82 — Fluency disorder in conditions classified elsewhere (via G20.-).

Each of these codes carries a Code First note naming this condition — when that code is reported, THIS code is sequenced first, ahead of it.

MS-DRG Grouper Relationships (FY2027)

Potential MS-DRG participation — not a DRG assignment.

FY2027 MS-DRG: not on the CMS CC/MCC list — as a secondary diagnosis this code does not change MS-DRG severity for that release.

Named in the grouper logic of 2 MS-DRGs: DRG 056 (MDC 01), DRG 057 (MDC 01).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):NVS004 — Parkinson's disease (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Parkinson and Other Degenerative Disease of Basal Ganglia) for risk-adjusted payment.

G20.A1 — Parkinson's disease without dyskinesia, without mention of fluctuations, G20.B1 — Parkinson's disease with dyskinesia, without mention of fluctuations, G20.B2 — Parkinson's disease with dyskinesia, with fluctuations, G20.C — Parkinsonism, unspecified, G21.3 — Postencephalitic parkinsonism, G21.4 — Vascular parkinsonism, G21.8 — Other secondary parkinsonism, G21.9 — Secondary parkinsonism, unspecified, G23.0 — Hallervorden-Spatz disease, G23.1 — Progressive supranuclear ophthalmoplegia [Steele-Richardson-Olszewski], G23.2 — Striatonigral degeneration, G23.3 — Hypomyelination with atrophy of the basal ganglia and cerebellum, G23.8 — Other specified degenerative diseases of basal ganglia, G23.9 — Degenerative disease of basal ganglia, unspecified, G90.3 — Multi-system degeneration of the autonomic nervous system

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Parkinson's disease).

G20 — Parkinson's disease, G20.A1 — Parkinson's disease without dyskinesia, without mention of fluctuations, G20.B1 — Parkinson's disease with dyskinesia, without mention of fluctuations, G20.B2 — Parkinson's disease with dyskinesia, with fluctuations, G20.C — Parkinsonism, unspecified

Contextual Map

Every relationship of G20.A2 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run G20.A2 with these 6 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes

Referenced by Excludes2 notes

Referenced by Code First instructions

Clinical classification (CCSR)

Risk adjustment (CMS-HCC)

  • HCC 199 — Parkinson and Other Degenerative Disease of Basal Ganglia [CMS-HCC]— CMS-HCC V28 · 2026

MS-DRG Grouper

MDC crossing

  • MDC 01 — Diseases and Disorders of the Nervous System[MDC crossing]: “Diseases and Disorders of the Nervous System — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 8,919 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027

Index entries

  • Disease, diseased, Parkinson's, without dyskinesia, with, fluctuations[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Disease, diseased, Parkinson's, without dyskinesia, with, OFF episodes[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027

Nearest codes

Change history

Relevant guides

Reference

Index terms and tables, published questions and FAQ, every source behind this page with its release and checksum, the date-of-service check and the complete change history.

Indexed Clinical Terms (2)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v44 Release, file and checksum · Publisher’s page
Risk adjustment Official source data
2026 Mid-Year Final ICD-10 Mappings + Model Software (cms.gov/files/zip/2026-midyear-final-icd-10-mappings.zip, 2026-midyear-final-model-software.zip) — CMS-HCC V28, PY2026 mid-year final release Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder-derived relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder editorial explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources

Labels on this page: Official source data · MedCoder-derived relationship · MedCoder editorial explanation. How to read the labels · All data sources and release dates · CMS coding rules

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "G20.A2 — Parkinson's disease without dyskinesia, with fluctuations." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/g20.a2-parkinsons-disease-without-dyskinesia-with-fluctuations

Change history

  • FY2024 — October 1, 2023
    Added to the code set
    Parkinson's disease without dyskinesia, with fluctuations
    FY2024 changes

Nearest Codes in This Family

Official ICD-10-CM classifications closest to G20.A2 in its code family, with their registry titles.

View all codes in the G20 family