What is ICD-10 code G04.2?

G04.2 is the ICD-10-CM diagnosis code for Bacterial meningoencephalitis and meningomyelitis, not elsewhere classified. It belongs to the ICD-10-CM chapter for diseases of the nervous system (g00-g99). G04.2 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. G04.2 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. G04.2 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. G04.2 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Which HCC does G04.2 map to under V28?

G04.2 has no payable CMS-HCC V28 mapping in the final FY2026 CMS file.

What RAF reference is published for G04.2?

G04.2 has no V28 reference coefficient because the final FY2026 source verifies no payable V28 mapping.

What is the V28 vs V24 difference for G04.2?

G04.2 has verified no payable V28 mapping in the final FY2026 source. Select a historical effective period before making any V24 comparison.

2026 ICD-10-CM G04.2: Bacterial meningoencephalitis

G04.2 is not a CMS-HCC payment code. MEAT criteria · RAF Calculator · HCC Buddy coding tools

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Code lookupG04.2Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Diseases of the nervous system (G00-G99) / Inflammatory diseases of the central nervous system (G00-G09)

G04.2

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Bacterial meningoencephalitis and meningomyelitis, not elsewhere classified

This code describes a serious brain and spinal cord infection caused by bacteria, where inflammation affects both the brain tissue and the membranes surrounding the brain and spinal cord. It is used when the bacterial infection doesn't fit into other more specific meningitis categories.

CMS-HCC V28

N/A

—

Not risk-adjusted for this model/period.

Not mapped

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

Mapped

HCC 003

HHS-HCC 003 adult, RAF varies...

Code-level coefficient reference

ESRD/PACE

N/A

—

Not risk-adjusted for this model/period.

Not mapped

RXHCC

N/A

—

Not risk-adjusted for this model/period.

Not mapped

Code Book Path

Official

G04Encephalitis, myelitis and encephalomyelitis

G04.2Bacterial meningoencephalitis and meningomyelitis, not elsewhere classified

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for G04.2 in this effective period.

Excludes 2

Official

acute transverse myelitis (G37.3)
alcoholic encephalopathy (G31.2)
multiple sclerosis (G35-)
myalgic encephalomyelitis (G93.32)
subacute necrotizing myelitis (G37.4)

Related Child Codes

Official

G04.0Acute disseminated encephalitis and encephalomyelitis (ADEM)

G04.1Tropical spastic paraplegia

G04.3Acute necrotizing hemorrhagic encephalopathy

G04.8Other encephalitis, myelitis and encephalomyelitis

G04.9Encephalitis, myelitis and encephalomyelitis, unspecified

Includes

Official

acute ascending myelitis
meningoencephalitis
meningomyelitis

Excludes 1

Official

encephalopathy NOS (G93.40)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for G04.2 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for G04.2 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for G04.2 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Always attempt to identify the specific causative organism (such as Streptococcus pneumoniae, Neisseria meningitidis, or Haemophilus influenzae) and code it first, as this provides more clinical specificity than the unspecified code G04.2

Verify that the documentation clearly indicates bacterial etiology rather than viral or other causes; if the organism is not identified, confirm with the provider before defaulting to this unspecified code

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is G04.2 an HCC code?

G04.2 is not in the CMS-HCC V28 or V24 community payment model. G04.2 also appears in the HHS-HCC commercial risk model (HCC 003 (HHS-HCC 003 adult, RAF varies by metal level)), which is a commercial market model rather than a Medicare Advantage payment mapping.

Code: G04.2
Description: Bacterial meningoencephalitis and meningomyelitis, not elsewhere classified
HCC (V28): No CMS-HCC V28 mapping
RAF reference coefficient: —
Billable: Yes
Payment year: 2026

Coder workflow notes

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This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).

What This Code Means

G04.2 is the ICD-10-CM diagnosis code for bacterial meningoencephalitis and meningomyelitis, not elsewhere classified. This code describes a serious brain and spinal cord infection caused by bacteria, where inflammation affects both the brain tissue and the membranes surrounding the brain and spinal cord. It is used when the bacterial infection doesn't fit into other more specific meningitis categories. G04.2 sits in the ICD-10-CM chapter for diseases of the nervous system (g00-g99), within the section covering inflammatory diseases of the central nervous system (g00-g09).

G04.2 has no mapping under the CMS-HCC V28 or V24 community payment models. G04.2 also appears in the HHS-HCC commercial risk model (HCC 003 (HHS-HCC 003 adult, RAF varies by metal level)), which is a commercial market model rather than a Medicare Advantage payment mapping. Do not assign V28 risk adjustment value from this page; verify the applicable model and payment year before using this code for risk adjustment.

HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for G04.2 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Always attempt to identify the specific causative organism (such as Streptococcus pneumoniae, Neisseria meningitidis, or Haemophilus influenzae) and code it first, as this provides more clinical specificity than the unspecified code G04.2
•Verify that the documentation clearly indicates bacterial etiology rather than viral or other causes; if the organism is not identified, confirm with the provider before defaulting to this unspecified code