G20.B2
BillableParkinson's disease with dyskinesia, with fluctuations
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is G20.B2 an HCC code?
Yes. G20.B2 maps to Parkinson and Huntington Diseases under the CMS-HCC V28 risk adjustment model (and Parkinson's and Huntington's Diseases under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
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.
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 Huntington Diseases (HCC 199) with a community, non-dual, aged base RAF weight of 0.000. Under the older CMS-HCC V24 model, G20.B2 maps to Parkinson's and Huntington's Diseases (HCC 78) with a community, non-dual, aged base RAF weight of 0.584. 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.
This code indicates the most complex presentation with both dyskinesia and fluctuations present. Because G20.B2 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. 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, RAF weights, 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