G35.C ICD-10-CM Code: Secondary progressive multiple sclerosis

Coder workflow for G35.C

MedCoder structured workflow — derived from this code’s own official record

Before you code G35.C

1. G35.C is not reportable as written. Select the more specific code beneath it that the documentation supports. Codes are reported to the highest level of specificity the classification provides (Guidelines I.B.2).

   ReviewG35.C0, G35.C1, G35.C2

   See the relationships section · Guide: How to choose an ICD-10-CM code →

Choose the right path

1. Does the documentation support one of the more specific codes beneath G35.C?
   Yes → Select that code and continue the checks below on its own page.
   No → G35.C cannot be reported as written; query for the specificity its subcategory needs.

   ReviewG35.C0, G35.C1, G35.C2

Consider G35.C. Then confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement

Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Don’t confuse G35.C with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of G35.C — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

• G35.D— Specificity relationship (Review)

  Overlapping diagnoses in the same category.

  Overlapping codes in the same category — the documentation decides which is the more specific fit.

  What moves you there: A record that documents no more than “Multiple sclerosis, unspecified” takes G35.D; specificity in the record moves it back here.

  Full comparison: G35.C vs G35.D →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Verify Before Coding

• Not billable as written — a more specific code is required: G35.C0, G35.C1, G35.C2.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name G35.C or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Excludes1 note: G37.3 — Acute transverse myelitis in demyelinating disease of central nervous system (via G35.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 1 Excludes2 note: G04 — Encephalitis, myelitis and encephalomyelitis (via G35.-).

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

Referenced by 2 Code First instructions: F02 — Dementia in other diseases classified elsewhere (via G35.-), F48.2 — Pseudobulbar affect (via G35.-).

Each of these codes carries a Code First note naming this condition — when that code is reported, THIS code is sequenced first, ahead of it.

Contextual Map

Every relationship of G35.C in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run G35.C with these 4 related codes in Claim Check

Hierarchy

• G00-G99 — Chapter 6: Diseases of the Nervous System (G00-G99) (G00-G99)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• G35-G37 — Demyelinating diseases of the central nervous system[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Referenced by Excludes1 notes

• G37.3 — Acute transverse myelitis in demyelinating disease of central nervous system[Excludes1](via G35.-): “multiple sclerosis (G35-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Excludes2 notes

• G04 — Encephalitis, myelitis and encephalomyelitis[Excludes2](via G35.-): “multiple sclerosis (G35-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Code First instructions

• F02 — Dementia in other diseases classified elsewhere[Code First](via G35.-): “multiple sclerosis (G35-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• F48.2 — Pseudobulbar affect[Code First](via G35.-): “multiple sclerosis (G35-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Nearest codes (10)

• G35 — Multiple sclerosis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• G35.A — Relapsing-remitting multiple sclerosis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• G35.B — Primary progressive multiple sclerosis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• G35.B0 — Primary progressive multiple sclerosis, unspecified[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• G35.B1 — Active primary progressive multiple sclerosis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• G35.B2 — Non-active primary progressive multiple sclerosis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• G35.C0 — Secondary progressive multiple sclerosis, unspecified[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• G35.C1 — Active secondary progressive multiple sclerosis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• and 2 more

Change history

• FY2026 — Added to the code set[Change history]— CMS release files (code change ledger) · icd10cm-fy2026

Common coding questions

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data

CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page

Claim edits Official source data

CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page

Change history and date-of-service validity Official source data

CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page

Comparisons, relationships and the contextual map MedCoder structured relationship

Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears

Summary and FAQ answers MedCoder explanation

Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Nearest Codes in This Family

Official ICD-10-CM classifications closest to G35.C in its code family, with their registry titles.

• G35 — Multiple sclerosis
• G35.A — Relapsing-remitting multiple sclerosis
• G35.B — Primary progressive multiple sclerosis
• G35.B0 — Primary progressive multiple sclerosis, unspecified
• G35.B1 — Active primary progressive multiple sclerosis
• G35.B2 — Non-active primary progressive multiple sclerosis
• G35.C0 — Secondary progressive multiple sclerosis, unspecified
• G35.C1 — Active secondary progressive multiple sclerosis
• G35.C2 — Non-active secondary progressive multiple sclerosis
• G35.D — Multiple sclerosis, unspecified

View all codes in the G35 family