Question 1

What is ICD-10 code G55?

Accepted Answer

G55 is the ICD-10-CM diagnosis code for nerve root and plexus compressions in diseases classified elsewhere. Compression or damage to nerve roots and nerve plexuses that occurs as a result of another disease or condition classified elsewhere in the ICD-10 system. G55 sits in the ICD-10-CM chapter for diseases of the nervous system (g00-g99), within the section covering nerve, nerve root and plexus disorders (g50-g59).

G55 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.

This is a secondary code - always code the underlying disease first (the condition causing the compression).

Question 2

Is G55 an HCC code?

Accepted Answer

No. G55 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 G55 billable?

Accepted Answer

Yes. G55 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. G55 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 G55?

Accepted Answer

G55 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 G55 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 G55?

Accepted Answer

This is a secondary code - always code the underlying disease first (the condition causing the compression) Common causes include tumors, infections, or inflammatory conditions; ensure both the cause and the nerve compression are documented

HCC Buddy Code Card

G55

Is G55 an HCC code?

What This Code Means

Coding Tips

Excludes 1, Do NOT code together

Code First

Code Hierarchy

Open G55 in the Interactive Encoder

G55 ICD-10-CM Code: Nerve root and plexus compressions in diseases classified elsewhere

HCC Buddy Code Card

G55

Is G55 an HCC code?

What This Code Means

Coding Tips

Excludes 1, Do NOT code together

Code First

Code Hierarchy

Open G55 in the Interactive Encoder