G98.8 ICD-10-CM Code: Other disorders of nervous system
HCC Buddy Code Card
Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.
FY 2026 Apr update / Diseases of the nervous system (G00-G99) / Other disorders of the nervous system (G89-G99)
G98.8
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceOther disorders of nervous system
This code is used for nervous system disorders that don't fit into other specific ICD-10-CM categories. It's a catch-all code for rare or unusual neurological conditions that have been documented by the physician but lack a more precise diagnostic code.
CMS-HCC V28
00
RAF 0
CMS-HCC V24
00
RAF 0
ACA/HHS
00
RAF 0
ESRD/PACE
00
RAF 0
RXHCC
00
RAF 0
Code Trumping
Basket needed
Code Book Path
Inclusion Terms
Official- Nervous system disorder NOS
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for G98.8 in this effective period.
Related Child Codes
Includes
Official- nervous system disorder NOS
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for G98.8 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for G98.8 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for G98.8 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for G98.8 in this effective period.
Buddy Documentation Tip
Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.
Is G98.8 an HCC code?
No. G98.8 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
G98.8 is the ICD-10-CM diagnosis code for other disorders of nervous system. This code is used for nervous system disorders that don't fit into other specific ICD-10-CM categories. It's a catch-all code for rare or unusual neurological conditions that have been documented by the physician but lack a more precise diagnostic code. G98.8 sits in the ICD-10-CM chapter for diseases of the nervous system (g00-g99), within the section covering other disorders of the nervous system (g89-g99).
G98.8 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.
Always attempt to use a more specific nervous system disorder code first; G98.8 should only be used when the condition truly cannot be classified elsewhere.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for G98.8 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Always attempt to use a more specific nervous system disorder code first; G98.8 should only be used when the condition truly cannot be classified elsewhere
- •Include detailed documentation from the physician describing the specific nervous system disorder to support medical necessity and justify the use of this unspecified code