2026 ICD-10-CM Diagnosis Code A40.1Sepsis due to streptococcus, group B
ICD-10-CM Codes›A00–B99›A30-A49›A40
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Risk Adjusts — HCC 2
- Not Chronic
A40.1 is a billable ICD-10-CM diagnosis code for sepsis due to streptococcus, group B. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 870 through 872. As a secondary diagnosis, it counts as a major complication or comorbidity (MCC) and places an inpatient stay in the highest severity level of its MS-DRG family. It does not count, however, when the principal diagnosis is one of 46 closely related codes. Coders also document this condition as sepsis caused by Streptococcus agalactiae. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Bacterial infections and Septicemia.
For Medicare Advantage risk adjustment, A40.1 maps to CMS-HCC Category 2 (Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock) under the V28 model, adding a risk factor of about 0.500 for a community, non-dual, aged beneficiary in payment year 2026.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
A40.1 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2026.
Source: CMS Payment Year 2026 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Sepsis caused by Streptococcus agalactiae
- Septic shock co-occurrent with acute organ dysfunction caused by Streptococcus
- Septic shock co-occurrent with acute organ dysfunction due to Gram-positive coccus
- Septic shock co-occurrent with acute organ dysfunction due to Group B streptococcus
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.
Patient EducationClinical
Sepsis
Sepsis is your body's overactive and extreme response to an infection. Sepsis is a life-threatening medical emergency. Without quick treatment, it can lead to tissue damage, organ failure, and even death.
The full article covers:
- What is sepsis?
- What causes sepsis?
- Who is more likely to develop sepsis?
- What are the symptoms of sepsis?
- What other problems can sepsis cause?
- How is sepsis diagnosed?
- What are the treatments for sepsis?
- Can sepsis be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert A40.1 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About A40.1Overview
What is the ICD-10 code for sepsis due to streptococcus, group B?
The ICD-10-CM code for sepsis due to streptococcus, group B is A40.1 (sometimes written as A401). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is A40.1 (Streptococcal sepsis) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report sepsis due to streptococcus, group B on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does A40.1 group to?
When sepsis due to streptococcus, group B is the principal diagnosis on an inpatient stay, it groups to MS-DRG 870, 871, 872, with relative weights from 1.0233 to 6.9118 depending on complications. Higher weights mean higher Medicare reimbursement.
Is A40.1 a CC or MCC?
CMS lists A40.1 as an MCC (major complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it places the inpatient stay in the highest-weighted DRG of its severity family. It does not count when the principal diagnosis is one of the 46 closely related codes in its exclusion list.
What is the ICD-9 equivalent of A40.1?
Under the General Equivalence Mappings, sepsis due to streptococcus, group B converts to ICD-9-CM 038.0 (streptococcal septicemia) and 995.91 (sepsis). The mapping is approximate, so confirm the match fits the documentation.
What HCC is A40.1?
A40.1 (sepsis due to streptococcus, group B) maps to CMS-HCC Category 2 (Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock), commonly written as HCC 2, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2026. It mapped to HCC 2 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. It does not map to any RxHCC in the Part D prescription drug model.
Does A40.1 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, A40.1 adds a risk adjustment factor of about 0.500 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.447 to 0.780 depending on the payment segment). HCC 2 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 2 category page.
