2027 ICD-10-CM Diagnosis Code B94.1Sequelae of viral encephalitis

ICD-10-CM Codes›A00–B99›B90-B94›B94

ICD-10-CM B94.1
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

B94.1 is a billable ICD-10-CM diagnosis code for sequelae of viral encephalitis. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 91 through 93. The code is exempt from POA reporting. Coders also document this condition as late effects of viral encephalitis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Sequela of specified infectious disease conditions and Sequela of specified nervous system conditions.

Code Identity

ICD-10-CM Code
B94.1
Billable Status
Yes — Valid for Submission
Code Describes
Sequelae of viral encephalitis
Short Description
Sequelae of viral encephalitis
Same as the full description in the CMS dataset.
Parent Code
B94
Sequelae of other and unspecified infectious and parasitic diseases

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionB90-B94Sequelae of infectious and parasitic diseases
CategoryB94Sequelae of other and unspecified infectious and parasitic diseases
This CodeB94.1Sequelae of viral encephalitis

Present on Admission (POA)Billing

B94.1 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review the other POA exempt codes in Sequelae of infectious and parasitic diseases (B90-B94).

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Late effects of viral encephalitis

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to B94.1: its own notes plus those printed at block B90-B94 and Chapter 1. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • diseases generally recognized as communicable or transmissible

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • carrier or suspected carrier of infectious disease (Z22.-)
  • certain localized infections - see body system-related chapters
  • infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)
  • infectious and parasitic diseases specific to the perinatal period (P35-P39)
  • influenza and other acute respiratory infections (J00-J22)

Code First

The underlying condition named in the note is sequenced before this code.

From Block B90-B94 Sequelae of infectious and parasitic diseases applies to 12 codes
  • condition resulting from (sequela) the infectious or parasitic disease

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • code to identify resistance to antimicrobial drugs (Z16.-)

Notes

General instructions on how these codes are used.

From Block B90-B94 Sequelae of infectious and parasitic diseases applies to 12 codes
  • Categories B90-B94 are to be used to indicate conditions in categories A00-B89 as the cause of sequelae, which are themselves classified elsewhere. The 'sequelae' include conditions specified as such; they also include residuals of diseases classifiable to the above categories if there is evidence that the disease itself is no longer present. Codes from these categories are not to be used for chronic infections. Code chronic current infections to active infectious disease as appropriate.

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name B94.1, its category, or a range that includes it.

Excludes1 2

These codes carry an Excludes1 note naming B94.1: they are not reported together with it, unless the two conditions are unrelated.

  • Block A80-A89 Viral and prion infections of the central nervous system
    sequelae of viral encephalitis (B94.1)
  • Z86.1 Personal history of infectious and parasitic diseases
    sequelae of infectious and parasitic diseases (B90-B94) names B90-B94, which includes this code

Notes 1

These notes mention B94.1.

  • Block B90-B94 Sequelae of infectious and parasitic diseases
    Categories B90-B94 are to be used to indicate conditions in categories A00-B89 as the cause of sequelae, which are themselves classified elsewhere. The 'sequelae' include conditions specified as such; they also include residuals of diseases classifiable to the above categories if there is evidence that the disease itself is no longer present. Codes from these categories are not to be used for chronic infections. Code chronic current infections to active infectious disease as appropriate. names B90-B94, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR INF011
Sequela of specified infectious disease conditions
Default principal diagnosis: inpatient Yes · outpatient Yes
CCSR NVS022
Sequela of specified nervous system conditions
Default principal diagnosis: inpatient No · outpatient No

Patient EducationClinical

Encephalitis

Encephalitis is inflammation (swelling) of the brain. It can happen when an infection or medical condition that affects the brain activates your immune system. The inflammation can cause a wide range of symptoms. In extreme cases, it can lead to brain damage, stroke, or even death.

The full article covers:

  • What is encephalitis?
  • What causes encephalitis?
  • Who is more likely to get encephalitis?
  • What are the symptoms of encephalitis?
  • How is encephalitis diagnosed?
  • What are the treatments for encephalitis?
  • Can encephalitis be prevented?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert B94.1 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
139.0 Late eff viral encephal
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About B94.1Overview

What is the ICD-10 code for sequelae of viral encephalitis?

The ICD-10-CM code for sequelae of viral encephalitis is B94.1 (sometimes written as B941). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is B94.1 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report sequelae of viral encephalitis on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does B94.1 group to?

When sequelae of viral encephalitis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 91, 92, 93, with relative weights from 0.7783 to 1.7050 depending on complications. Higher weights mean higher Medicare reimbursement.

Is B94.1 exempt from POA reporting?

Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for sequelae of viral encephalitis on inpatient claims. The code appears in the Sequelae of infectious and parasitic diseases (B90-B94) range of the CMS exempt list.

What is the ICD-9 equivalent of B94.1?

Under the General Equivalence Mappings, sequelae of viral encephalitis converts to ICD-9-CM 139.0 (late eff viral encephal). The mapping is a direct match.