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G20.B2 ICD-10-CM Code: Parkinson's disease with dyskinesia, with fluctuations

G20.B2 maps to CMS-HCC V28 199. A source-labeled RAF reference is available. Documentation must support MEAT. MEAT criteria · RAF Calculator · HCC coding software

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FY 2026 Apr update / Diseases of the nervous system (G00-G99) / Extrapyramidal and movement disorders (G20-G26)

G20.B2

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Parkinson's disease with dyskinesia, with fluctuations

Parkinson's disease with both involuntary movements (dyskinesia) and motor fluctuations, representing more advanced disease with complex symptom patterns.

Buddy the Bee presenting code insight

Buddy Insight

Parkinson's disease with both dyskinesia and motor fluctuations represents the most complex and advanced stage of medication-managed Parkinson's disease.

CMS-HCC V28

HCC 199

Code-level coefficient reference

CMS-HCC V24

Historical

Historical

Not used for CY2026 payment

ACA/HHS

HCC 119

Code-level coefficient reference

ESRD/PACE

HCC 78

Code-level coefficient reference

RXHCC

HCC 161

Code-level coefficient reference

Code Book Path

Official
G20Parkinson's disease
G20.BParkinson's disease with dyskinesia
G20.B2Parkinson's disease with dyskinesia, with fluctuations

Inclusion Terms

Official
  • Parkinson's disease with dyskinesia, with OFF episodes

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for G20.B2 in this effective period.

Related Child Codes

Official
G20.B1Parkinson's disease with dyskinesia, without mention of fluctuations

Includes

Official

ICD-10-CM does not list Includes notes for G20.B2 in this effective period.

Excludes 1

Official
  • drug induced dystonia (G24.0-)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for G20.B2 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for G20.B2 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for G20.B2 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance
Confirmed Parkinson's disease diagnosis
Dyskinesia explicitly documented with description of involuntary movements
Motor fluctuations explicitly documented (on-off phenomena, wearing-off)
Impact of both complications on daily functioning

MEAT Support

HCC Buddy guidance
Confirmed Parkinson's disease diagnosis
Dyskinesia explicitly documented with description of involuntary movements
Motor fluctuations explicitly documented (on-off phenomena, wearing-off)
Impact of both complications on daily functioning

Audit Caution

HCC Buddy guidance
Defaulting to unspecified Parkinson's codes when documentation clearly describes both complications
Not documenting both dyskinesia and fluctuations explicitly in the clinical note
Confusing the natural disease symptoms with medication-related complications
Failing to capture this most specific code which reflects the highest disease complexity

Common Mistakes

HCC Buddy guidance
G20.A2 — Parkinson's disease without dyskinesia, with fluctuations: has fluctuations but no dyskinesia
G20.B1 — Parkinson's disease with dyskinesia, without fluctuations: has dyskinesia but no fluctuations
G20.A1 — Parkinson's disease without dyskinesia, without fluctuations: earliest/simplest presentation
G20.C — Parkinsonism, unspecified: grossly insufficient for this complex presentation

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is G20.B2 an HCC code?

Yes. G20.B2 (Parkinson's disease with dyskinesia, with fluctuations) maps to HCC 199, Parkinson and Other Degenerative Disease of Basal Ganglia under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.615. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: G20.B2 is billable and maps to V28 HCC 199, Parkinson and Other Degenerative Disease of Basal Ganglia. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code
G20.B2
Description
Parkinson's disease with dyskinesia, with fluctuations
HCC (V28)
HCC 199 — Parkinson and Other Degenerative Disease of Basal Ganglia
RAF reference coefficient
0.615
Billable
Yes
Payment year
2026

HCC Category Mapping

V28HCC 199, Parkinson and Other Degenerative Disease of Basal Ganglia
0.615
ESRDHCC 78, Parkinsons and Huntingtons Diseases
Not separately weighted
RxHCCHCC 161, Parkinson Disease
Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work G20.B2 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT Criteria for G20.B2

For G20.B2 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

  • MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
  • EEvaluate: test results, medication response, or physical findings reviewed by the provider
  • AAssess: explicit mention in the assessment or plan with acknowledgment of status
  • TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed G20.B2 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

G20.B2 is the ICD-10-CM diagnosis code for parkinson's disease with dyskinesia, with fluctuations. Parkinson's disease with both involuntary movements (dyskinesia) and motor fluctuations, representing more advanced disease with complex symptom patterns. G20.B2 sits in the ICD-10-CM chapter for diseases of the nervous system (g00-g99), within the section covering extrapyramidal and movement disorders (g20-g26).

Under the CMS-HCC V28 risk adjustment model, G20.B2 maps to Parkinson and Other Degenerative Disease of Basal Ganglia (HCC 199) with a source-labeled community, non-dual, aged reference coefficient of 0.615. No V24 mapping is shown for G20.B2; use the applicable model and payment year when reviewing the V28 mapping. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

This code indicates the most complex presentation with both dyskinesia and fluctuations present. Because G20.B2 maps to an HCC category, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) before the diagnosis is used for risk adjustment. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for G20.B2 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •This code indicates the most complex presentation with both dyskinesia and fluctuations present
  • •Document both complications clearly in the medical record to justify this code

Clinical Significance

Parkinson's disease with both dyskinesia and motor fluctuations represents the most complex and advanced stage of medication-managed Parkinson's disease. These patients have the highest care needs, often requiring consideration for advanced therapies like deep brain stimulation, continuous levodopa-carbidopa intestinal gel infusion, or apomorphine pump.

Documentation Requirements

  • ✓Confirmed Parkinson's disease diagnosis
  • ✓Dyskinesia explicitly documented with description of involuntary movements
  • ✓Motor fluctuations explicitly documented (on-off phenomena, wearing-off)
  • ✓Impact of both complications on daily functioning
  • ✓Current medication regimen and optimization attempts
  • ✓Evaluation for or status of advanced therapies (deep brain stimulation, pump therapy)

Commonly Confused Codes

  • •G20.A2: Parkinson's disease without dyskinesia, with fluctuations: has fluctuations but no dyskinesia
  • •G20.B1: Parkinson's disease with dyskinesia, without fluctuations: has dyskinesia but no fluctuations
  • •G20.A1: Parkinson's disease without dyskinesia, without fluctuations: earliest/simplest presentation
  • •G20.C: Parkinsonism, unspecified: grossly insufficient for this complex presentation

Child Codes

G20.B1Parkinson's disease with dyskinesia, without mention of fluctuations
HCC 199
G20.B2Parkinson's disease with dyskinesia, with fluctuations
HCC 199

Code Hierarchy

└G20Parkinson's disease└G20.BParkinson's disease with dyskinesia└G20.B2Parkinson's disease with dyskinesia, with fluctuations
└G20.B2Parkinson's disease with dyskinesia, with fluctuations

G20.B2 code history

Code setChange
FY2024 (effective Oct 1, 2023)Added to the code set

Source: official CMS ICD-10-CM order and addenda files, FY2016 through FY2027.

Because G20.B2 maps to an HCC category, the documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) before the diagnosis is used for risk adjustment.

G20.B2 maps to CMS-HCC V28 category 199, Parkinson and Other Degenerative Disease of Basal Ganglia. See the ICD-10 to HCC mapping hub for how the V28 crosswalk works. The mapping identifies a payment HCC category for G20.B2. Review its source-labeled HCC coefficient above, check the RAF Calculator with complete member context for CMS-HCC V28 PY2026, and confirm the documentation the chart needs before the code is submitted. HCC Buddy shows no RAF score unless every required source and calculation check passes.

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