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ICD-10-CM 2027 diagnosis code

G35.CSecondary progressive multiple sclerosis

Not billable — use a more specific code

G35.C is a header code, so it can't be reported by itself. Choose one of the 3 more specific codes beneath it.

Code last changed in FY2026 (effective October 1, 2025). Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About G35.C

G35.C is the ICD-10-CM diagnosis code for secondary progressive multiple sclerosis. It belongs to category G35 (multiple sclerosis), block G35-G37 (demyelinating diseases of the central nervous system) and chapter 6 (diseases of the nervous system). It is a header code, so it can't be reported by itself; one of its 3 subcodes must be used instead.

Within G35 (multiple sclerosis), G35.C is specifically for secondary progressive multiple sclerosis. Related codes cover Relapsing-remitting multiple sclerosis (G35.A), primary progressive multiple sclerosis (G35.B) and unspecified (G35.D).

To report this condition, pick the subcode that matches the documentation: G35.C0 (unspecified), G35.C1 (sclerosis) and G35.C2 (sclerosis).

It was added in FY2026, effective October 1, 2025.

Specific codes under G35.C

Notes that apply from higher levels

Instructions written at a parent level also apply to G35.C.

Broader instructions also apply from Chapter 6: Diseases of the nervous system.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2026 (effective 10/1/2025): Added
  • No changes since FY2026.

Common questions about G35.C

Is G35.C billable?

No. G35.C is a header code. Report one of its more specific subcodes instead.