What is ICD-10 code A40.1?

A40.1 is the ICD-10-CM diagnosis code for Sepsis due to streptococcus, group B. It belongs to the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99). A40.1 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. A40.1 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. A40.1 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. A40.1 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 A40.1 map to under V28?

A40.1 maps to CMS-HCC V28 HCC 2 (Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock). The category numbers, labels, and conditions come from the CMS-HCC V28 model file for payment year 2026.

What documentation supports A40.1?

Always verify the documentation specifies Group B Streptococcus (not other streptococcal groups) and confirms sepsis diagnosis before assigning this code This code requires a secondary code for the site of infection or organ dysfunction (such as septic shock R65.21, acute kidney injury, or respiratory failure) to fully capture the clinical picture and severity Because A40.1 maps to an HCC category, the documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) before the diagnosis is used for risk adjustment. See the MEAT criteria checklist at /meat-criteria for what Monitor, Evaluate, Assess, or Treat looks like in a note. MEAT is generic documentation evidence, not a payer-specific rule.

2026 ICD-10-CM A40.1: Sepsis due to streptococcus

A40.1 maps to CMS-HCC V28 2. A source-labeled RAF reference is available. Documentation must support MEAT. MEAT criteria · RAF Calculator · free HCC coding tools

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Code lookupA40.1Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Certain infectious and parasitic diseases (A00-B99) / Other bacterial diseases (A30-A49)

A40.1

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

Sepsis due to streptococcus, group B

This is a serious bloodstream infection caused by Group B Streptococcus bacteria, which can spread throughout the body and cause life-threatening complications. Group B Strep is commonly found in the digestive and reproductive tracts and can be particularly dangerous in newborns, pregnant women, and elderly patients.

Buddy Insight

CMS-HCC V28

Mapped

HCC 2

Septicemia, Sepsis, Systemic ...

Code-level coefficient reference

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 002

HHS-HCC 002 adult, RAF varies...

Code-level coefficient reference

ESRD/PACE

Mapped

HCC 2

Septicemia/Sepsis/Systemic In...

Code-level coefficient reference

RXHCC

N/A

—

Not risk-adjusted for this model/period.

Not mapped

Code Book Path

Official

A40Streptococcal sepsis

A40.1Sepsis due to streptococcus, group B

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for A40.1 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for A40.1 in this effective period.

Related Child Codes

Official

A40.0Sepsis due to streptococcus, group A

A40.3Sepsis due to Streptococcus pneumoniae

A40.8Other streptococcal sepsis

A40.9Streptococcal sepsis, unspecified

Includes

Official

ICD-10-CM does not list Includes notes for A40.1 in this effective period.

Excludes 1

Official

neonatal (P36.0-P36.1)
puerperal sepsis (O85)
sepsis due to Streptococcus, group D (A41.81)

Code First

Official

, 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-)

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for A40.1 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for A40.1 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Blood cultures positive for Group B Streptococcus or clinical sepsis with GBS identified from relevant source

Patient demographics and risk context (neonate, peripartum, elderly, diabetic, immunocompromised)

In neonates: timing of onset (early <7 days vs. late 7-90 days), maternal GBS colonization status, intrapartum antibiotic prophylaxis received or not

Sepsis severity assessment with organ dysfunction documentation

MEAT Support

HCC Buddy guidance

Blood cultures positive for Group B Streptococcus or clinical sepsis with GBS identified from relevant source

Patient demographics and risk context (neonate, peripartum, elderly, diabetic, immunocompromised)

In neonates: timing of onset (early <7 days vs. late 7-90 days), maternal GBS colonization status, intrapartum antibiotic prophylaxis received or not

Sepsis severity assessment with organ dysfunction documentation

Audit Caution

HCC Buddy guidance

Neonatal GBS sepsis uses P36.0, not A40.1 — do not use adult sepsis codes on newborn records

In postpartum patients, consider O85 (Puerperal sepsis) as principal diagnosis with A40.1 as the causal organism code

Code any concurrent meningitis (G00.2 for streptococcal meningitis) separately when documented

Always add R65.20/R65.21 for severe sepsis/septic shock in adult patients

Common Mistakes

HCC Buddy guidance

A40.0 (Sepsis due to Streptococcus, group A) — Group A causes different clinical syndromes (pharyngitis, necrotizing fasciitis); Group B is neonatal/peripartum-associated

P36.0 (Sepsis of newborn due to Streptococcus, group B) — For neonatal GBS sepsis, use P36.0, not A40.1 — the P codes are used on the newborn record

A40.9 (Streptococcal sepsis, unspecified) — Use A40.1 when GBS is identified; do not default to unspecified

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 A40.1 an HCC code?

Yes. A40.1 (Sepsis due to streptococcus, group B) maps to HCC 2, Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.500. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: A40.1 is billable and maps to V28 HCC 2, Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: A40.1
Description: Sepsis due to streptococcus, group B
HCC (V28): HCC 2 — Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock
RAF reference coefficient: 0.500
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 2, Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock

0.500

ESRDHCC 2, Septicemia/Sepsis/Systemic Inflammatory Response Syndrome/Shock

Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work A40.1 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT Criteria for A40.1

For A40.1 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
EEvaluate: test results, medication response, or physical findings reviewed by the provider
AAssess: explicit mention in the assessment or plan with acknowledgment of status
TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed A40.1 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

A40.1 is the ICD-10-CM diagnosis code for sepsis due to streptococcus, group b. This is a serious bloodstream infection caused by Group B Streptococcus bacteria, which can spread throughout the body and cause life-threatening complications. Group B Strep is commonly found in the digestive and reproductive tracts and can be particularly dangerous in newborns, pregnant women, and elderly patients. A40.1 sits in the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99), within the section covering other bacterial diseases (a30-a49).

Under the CMS-HCC V28 risk adjustment model, A40.1 maps to Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock (HCC 2) with a source-labeled community, non-dual, aged reference coefficient of 0.500. No V24 mapping is shown for A40.1; use the applicable model and payment year when reviewing the V28 mapping. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

Always verify the documentation specifies Group B Streptococcus (not other streptococcal groups) and confirms sepsis diagnosis before assigning this code. Because A40.1 maps to an HCC category, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) before the diagnosis is used for risk adjustment. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for A40.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Always verify the documentation specifies Group B Streptococcus (not other streptococcal groups) and confirms sepsis diagnosis before assigning this code
•This code requires a secondary code for the site of infection or organ dysfunction (such as septic shock R65.21, acute kidney injury, or respiratory failure) to fully capture the clinical picture and severity

Clinical Significance

Sepsis due to Group B Streptococcus (Streptococcus agalactiae) predominantly affects neonates (early and late-onset neonatal sepsis), pregnant/postpartum women, and elderly or immunocompromised adults. In neonates, it remains a leading cause of sepsis and meningitis despite universal prenatal screening, and in adults it is increasingly recognized as a cause of serious invasive disease.

Documentation Requirements

✓Blood cultures positive for Group B Streptococcus or clinical sepsis with GBS identified from relevant source
✓Patient demographics and risk context (neonate, peripartum, elderly, diabetic, immunocompromised)
✓In neonates: timing of onset (early <7 days vs. late 7-90 days), maternal GBS colonization status, intrapartum antibiotic prophylaxis received or not
✓Sepsis severity assessment with organ dysfunction documentation
✓Source of infection if identified (urinary tract, skin/soft tissue, endometritis, osteoarticular)

Commonly Confused Codes

•A40.0 (Sepsis due to Streptococcus, group A): Group A causes different clinical syndromes (pharyngitis, necrotizing fasciitis); Group B is neonatal/peripartum-associated
•P36.0 (Sepsis of newborn due to Streptococcus, group B): For neonatal GBS sepsis, use P36.0, not A40.1: the P codes are used on the newborn record
•A40.9 (Streptococcal sepsis, unspecified): Use A40.1 when GBS is identified; do not default to unspecified