2026 ICD-10-CM Diagnosis Code G35.B1Active primary progressive multiple sclerosis

ICD-10-CM Codes›G00–G99›G35-G37›G35

ICD-10-CM G35.B1
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

G35.B1 is a billable ICD-10-CM diagnosis code for active primary progressive multiple sclerosis. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026).

Code Identity

ICD-10-CM Code
G35.B1
Billable Status
Yes — Valid for Submission
Code Describes
Active primary progressive multiple sclerosis
Short Description
Active primary progressive multiple sclerosis
Same as the full description in the CMS dataset.
Parent Code
G35.B
Primary progressive multiple sclerosis

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG35-G37Demyelinating diseases of the central nervous system
CategoryG35Multiple sclerosis
This CodeG35.B1Active primary progressive multiple sclerosis

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Primary progressive multiple sclerosis with evidence of inflammatory disease activity

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Sclerosis, sclerotic
      • multiple (brain stem) (cerebral) (disseminated) (generalized) (spinal cord)
        • progressive
          • primary
            • with
              • evidence of inflammatory disease activity
    • Sclerosis, sclerotic
      • multiple (brain stem) (cerebral) (disseminated) (generalized) (spinal cord)
        • progressive
          • primary
            • active

Code History & ChangesHistory

New Code G35.B1 was added to the ICD-10-CM code set for FY 2026, effective October 1, 2025.

Replacement G35.B1 replaces the following previously assigned code(s):

  • G35 - Multiple sclerosis
FY 2026AddedAdded to the ICD-10-CM code setEffective October 1, 2025.
FY 2026CurrentRevised in the current code setEffective October 1, 2025 through September 30, 2026.

Questions About G35.B1Overview

Is G35.B1 (Primary progressive multiple sclerosis) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report active primary progressive multiple sclerosis on HIPAA-covered claims from October 1, 2025 through September 30, 2026.