Multiple Sclerosis ICD-10-CM codes

G35 was expanded in FY2025 from a single code into subtypes. G35.A is relapsing-remitting MS, G35.B- is primary progressive (G35.B0 unspecified, G35.B1 active, G35.B2 non-active), G35.C- is secondary progressive (G35.C0, G35.C1 active, G35.C2 non-active), and G35.D is multiple sclerosis, unspecified. The old code G35 alone is no longer valid for dates of service on or after October 1, 2024.

Assign the subtype from the provider's documented clinical course. Active and non-active refer to documented disease activity, meaning new relapses or new MRI lesions within the provider's stated period; do not infer activity from a current exacerbation without documentation. When only MS is documented, G35.D is correct, and it is worth querying because the subtype now drives DRG and quality reporting.

Neuromyelitis optica (Devic disease, G36.0) and unspecified demyelinating disease (G37.9) are separate conditions and are not coded as MS. Symptoms that are integral to MS are not coded separately, but functional deficits the provider addresses, such as dysarthria (R47.1) or ataxia (R27.0), may be reported. Disease-modifying therapy can be captured with Z79.899.