2027 ICD-10-CM Diagnosis Code A40.0Sepsis due to streptococcus, group A
ICD-10-CM Codes›A00–B99›A30-A49›A40
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Risk Adjusts — HCC 2
- Not Chronic
A40.0 is a billable ICD-10-CM diagnosis code for sepsis due to streptococcus, group A. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) 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 pyogenes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Bacterial infections and Septicemia.
For Medicare Advantage risk adjustment, A40.0 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 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
A40.0 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 2027.
Source: CMS Payment Year 2027 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 pyogenes
- Septic shock co-occurrent with acute organ dysfunction caused by Streptococcus
- Septic shock co-occurrent with acute organ dysfunction due to Group A streptococcus
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to A40.0: its own notes plus those printed at A40 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.
- diseases generally recognized as communicable or transmissible
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
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.
- 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.
- 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 a second code, after this one, to fully describe the condition.
- code to identify resistance to antimicrobial drugs (Z16.-)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name A40.0, its category, or a range that includes it.
Excludes1 1
These codes carry an Excludes1 note naming A40.0: they are not reported together with it, unless the two conditions are unrelated.
Code First 2
These codes say to code first a condition named in the note, and A40.0 is one of the conditions named.
Use Additional Code 6
These codes say to use an additional code from the note, and A40.0 is one of the codes named.
- J95.02 Infection of tracheostomy stomasepsis (A40, A41.-) names A40, which includes this code
- K94.02 Colostomy infectionsepsis (A40.-, A41.-) names A40.-, which includes this code
- K94.12 Enterostomy infectionsepsis (A40.-, A41.-) names A40.-, which includes this code
- K94.22 Gastrostomy infectionsepsis (A40.-, A41.-) names A40.-, which includes this code
- K95.01 Infection due to gastric band proceduresepsis (A40.-, A41.-) names A40.-, which includes this code
- K95.81 Infection due to other bariatric proceduresepsis (A40.-, A41.-) names A40.-, 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.
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 A40.0 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About A40.0Overview
What is the ICD-10 code for sepsis due to streptococcus, group A?
The ICD-10-CM code for sepsis due to streptococcus, group A is A40.0 (sometimes written as A400). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is A40.0 (Streptococcal sepsis) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report sepsis due to streptococcus, group A on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does A40.0 group to?
When sepsis due to streptococcus, group A is the principal diagnosis on an inpatient stay, it groups to MS-DRG 872, 871, 870, with relative weights from 1.0066 to 6.9432 depending on complications. Higher weights mean higher Medicare reimbursement.
Is A40.0 a CC or MCC?
CMS lists A40.0 as an MCC (major complication or comorbidity) for FY 2027. 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.
Can A40.0 be reported with O85?
Not as a rule. The Excludes1 note at A40, which applies to A40.0, lists "puerperal sepsis (O85)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
What HCC is A40.0?
A40.0 (sepsis due to streptococcus, group A) 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 2027. 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 A40.0 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, A40.0 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.
