FY2027 ICD-10-CM reference
G04: Encephalitis, myelitis and encephalomyelitis
By the HCC Buddy Coding Team
The official ICD-10-CM descriptor is Encephalitis, myelitis and encephalomyelitis. The FY2027 annual edition starts October 1, 2026. Check the edition that applies to the encounter or inpatient discharge, including any April update.
Nonbillable heading. Verified against the official FY2027 order file.
CMS-HCC V28
Not applicable to this nonbillable heading
CMS-HCC V24
Not applicable to this nonbillable heading
ESRD
Not applicable to this nonbillable heading
PACE
Not applicable to this nonbillable heading
RxHCC
Not applicable to this nonbillable heading
HHS-HCC
Not applicable to this nonbillable heading
More specific FY2027 codes
- G04.0: Acute disseminated encephalitis and encephalomyelitis (ADEM)Nonbillable heading
- G04.1: Tropical spastic paraplegiaBillable code
- G04.2: Bacterial meningoencephalitis and meningomyelitis, not elsewhere classifiedBillable code
- G04.3: Acute necrotizing hemorrhagic encephalopathyNonbillable heading
- G04.8: Other encephalitis, myelitis and encephalomyelitisNonbillable heading
- G04.9: Encephalitis, myelitis and encephalomyelitis, unspecifiedNonbillable heading
FY2027 Tabular instructions
Instructions below include applicable chapter, section and parent-code notes. Each note identifies where it appears in the official source.
Excludes2
certain conditions originating in the perinatal period (P04-P96)
Source: G00-G99 (chapter, inherited).
Excludes2
certain infectious and parasitic diseases (A00-B99)
Source: G00-G99 (chapter, inherited).
Excludes2
complications of pregnancy, childbirth and the puerperium (O00-O9A)
Source: G00-G99 (chapter, inherited).
Excludes2
congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
Source: G00-G99 (chapter, inherited).
Excludes2
endocrine, nutritional and metabolic diseases (E00-E88)
Source: G00-G99 (chapter, inherited).
Excludes2
injury, poisoning and certain other consequences of external causes (S00-T88)
Source: G00-G99 (chapter, inherited).
Excludes2
neoplasms (C00-D49)
Source: G00-G99 (chapter, inherited).
Excludes2
symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Source: G00-G99 (chapter, inherited).
Includes
acute ascending myelitis
Source: G04 (category, direct).
Includes
meningoencephalitis
Source: G04 (category, direct).
Includes
meningomyelitis
Source: G04 (category, direct).
Excludes1
encephalopathy NOS (G93.40)
Source: G04 (category, direct).
Excludes2
acute transverse myelitis (G37.3)
Source: G04 (category, direct).
Excludes2
alcoholic encephalopathy (G31.2)
Source: G04 (category, direct).
Excludes2
multiple sclerosis (G35-)
Source: G04 (category, direct).
Excludes2
myalgic encephalomyelitis (G93.32)
Source: G04 (category, direct).
Excludes2
subacute necrotizing myelitis (G37.4)
Source: G04 (category, direct).
Excludes2
toxic encephalitis (G92.8)
Source: G04 (category, direct).
Excludes2
toxic encephalopathy (G92.8)
Source: G04 (category, direct).
Compare the FY2027 additions, removals and billable-status changes
What does G04 mean in FY2027?
The official ICD-10-CM descriptor is Encephalitis, myelitis and encephalomyelitis. The FY2027 annual edition starts October 1, 2026. Check the edition that applies to the encounter or inpatient discharge, including any April update.
Is G04 billable in FY2027?
The FY2027 order file marks G04 as a nonbillable heading. Select a complete billable child code.
Does G04 map to an HCC?
Risk-model mapping is not applicable to this nonbillable heading. Check a complete billable child code.
Source: CMS FY2027 ICD-10-CM order file. Payment model: CMS CY 2027 Rate Announcement. Read the FY2027 Official Guidelines.
Review the FY2026 April edition