Alphabetic Index FY2027

A40.0

Sepsis due to streptococcus, group A

FY2027Chapter 1: Certain infectious and parasitic diseases/A30–A49 Other bacterial diseases

BillableComplete code, valid to report
Care settingsHome Health Primary · MMTA - Infectious Disease, Neoplasms, and Blood-Forming DiseasesHospital MCC

A40.0 (also written A400) is a billable ICD-10-CM diagnosis code for sepsis due to streptococcus, group A. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 5 codes in category A40 (Streptococcal sepsis). The Alphabetic Index lists it under 2 entries. Its coding notes include a Code first instruction, a Use additional code instruction, 3 Excludes1 entries and 5 Excludes2 entries.

Guidelines tip

From the FY2027 Official Guidelines. ICD10Ref adds no rules of its own.

Sepsis is coded to the underlying systemic infection, with A41.9 as the default. Urosepsis has no default code and the provider must be queried. R65.2 needs documented severe sepsis or associated organ dysfunction.

Guidelines I.C.1.d.1.aSepsis, severe sepsis and urosepsisRead the official text

Code first

If the underlying condition listed here is present and known, sequence it first.

Inherited from A40 Streptococcal sepsis
  • , if applicable, postprocedural sepsis (T81.44-)
  • sepsis due to central venous catheter (T80.211-)
  • streptococcal sepsis during labor (O75.3)
  • streptococcal sepsis following abortion or ectopic or molar pregnancy (O03.37, O03.87, O04.87, O07.37, O08.82)
  • streptococcal sepsis following immunization (T88.0-)
  • streptococcal sepsis following infusion, transfusion or therapeutic injection (T80.22-, T80.29-)

Use additional code

Add the listed code as a secondary code, if known.

Also from chapter/block level (1 note)
Inherited from Chapter 1 Certain infectious and parasitic diseases
  • code to identify resistance to antimicrobial drugs (Z16.-)

Excludes1

Not coded here. The listed conditions generally should not be reported together.

Inherited from A40 Streptococcal sepsis

Excludes2

Not included here. Both codes may be reported if the patient has both conditions.

Also from chapter/block level (5 notes)
Inherited from Chapter 1 Certain infectious and parasitic diseases
  • 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)

Care settings

How CMS programs treat this code. These are CMS claim edits and list entries, not coverage or eligibility rules.

Home Health Primary

Accepted as the primary (principal) diagnosis on a home health claim. The Home Health Grouper assigns it to the MMTA - Infectious Disease, Neoplasms, and Blood-Forming Diseases clinical group.

Source: CMS Home Health Grouper Software v07.2.26, effective October 1, 2026

Hospital MCC

Counts as a major complication or comorbidity (MCC) when reported as a secondary diagnosis on an inpatient claim. It does not count when the principal diagnosis is one of the 46 codes in its exclusion list. Some MS-DRGs also ignore a CC or MCC that defines the DRG.

Source: CMS MS-DRG Definitions Manual v44, effective October 1, 2026, Appendix C

Includes

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

Also from chapter/block level (1 note)
Inherited from Chapter 1 Certain infectious and parasitic diseases
  • diseases generally recognized as communicable or transmissible

Alphabetic Index terms

Terms the official Alphabetic Index lists for this code. 2 entries