Question 1

What is ICD-10 code G26?

Accepted Answer

G26 is the ICD-10-CM diagnosis code for extrapyramidal and movement disorders in diseases classified elsewhere. This code describes movement disorders and problems with involuntary muscle control that occur as a result of another disease or condition. These disorders affect the brain's ability to coordinate smooth, controlled movements. G26 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).

G26 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.

G26 is a secondary code that requires documentation of the underlying disease causing the movement disorder; always code the primary condition first.

Question 2

Is G26 an HCC code?

Accepted Answer

No. G26 is a billable ICD-10-CM code but does not map to any payment HCC category under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can still be reported on Medicare Advantage encounter data submissions, but it does not contribute to the beneficiary's Risk Adjustment Factor (RAF) score and therefore does not affect the risk-adjusted capitation payment to the plan. V28 reached 100% phase-in for payment year 2026.

Question 3

Is G26 billable?

Accepted Answer

Yes. G26 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. G26 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Question 4

What is the V28 vs V24 difference for G26?

Accepted Answer

G26 does not map to a payment HCC under either the CMS-HCC V28 risk adjustment model or the older V24 model. V28 reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition. Because neither model rewards G26 with a risk adjustment factor, it contributes zero to a Medicare Advantage beneficiary's RAF score in either version. Coders should check whether provider documentation supports a more specific child code that does map to a payment HCC.

Question 5

What should coders know when reporting G26?

Accepted Answer

G26 is a secondary code that requires documentation of the underlying disease causing the movement disorder; always code the primary condition first Common underlying conditions include Parkinson's disease, Huntington's disease, Wilson's disease, and other neurological conditions; verify the causal relationship is documented in the medical record

G26

Is G26 an HCC code?

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Open G26 in the Interactive Encoder