2026 ICD-10-CM Diagnosis Code S02.40ABMalar fracture, right side, initial encounter for open fracture
ICD-10-CM Codes›S00–T88›S00-S09›S02
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 399
- 7th Character B — Initial, Open Fracture
- Not Chronic
S02.40AB is a billable ICD-10-CM diagnosis code for malar fracture, right side, initial encounter for open fracture. The 7th character B reports the initial encounter for an open fracture. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 11 through 13, 157 through 159, 963 through 965. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 459 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Fracture of head and neck, initial encounter.
For Medicare Advantage risk adjustment, S02.40AB maps to CMS-HCC Category 399 (Major Head Injury without Loss of Consciousness) under the V28 model, adding a risk factor of about 0.199 for a community, non-dual, aged beneficiary in payment year 2026.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
S02.40AB 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.
Coding GuidelinesGuidance
The principles of multiple coding of injuries should be followed in coding fractures. Fractures of specified sites are coded individually by site, to the level of detail furnished by medical record content.
A fracture not indicated as open or closed should be coded to closed. A fracture not indicated whether displaced or not displaced should be coded to displaced.
Initial vs. Subsequent Encounter for Fractures
Traumatic fractures are coded using the appropriate 7th character for initial encounter (A, B, C) while the patient is receiving active treatment for the fracture. The appropriate 7th character for initial encounter should also be assigned for a patient who delayed seeking treatment for the fracture or nonunion.
Fractures are coded using the appropriate 7th character for subsequent care for encounters after the patient has completed active treatment of the fracture and is receiving routine care for the fracture during the healing or recovery phase.
Care for complications of surgical treatment for fracture repairs during the healing or recovery phase should be coded with the appropriate complication codes.
Care of complications of fractures, such as malunion and nonunion, should be reported with the appropriate 7th character for subsequent care with nonunion (K, M, N) or subsequent care with malunion (P, Q, R).
The open fracture designations in the assignment of the 7th character for fractures of the forearm, femur and lower leg, including ankle are based on the Gustilo open fracture classification. When the Gustilo classification type is not specified for an open fracture, the 7th character for open fracture type I or II should be assigned (B, E, H, M, Q).
Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Facial Injuries and Disorders
Face injuries and disorders can cause pain and affect how you look. In severe cases, they can affect sight, speech, breathing and your ability to swallow. Fractures (broken bones), especially in the bones of your nose, cheekbone and jaw, are common facial injuries.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert S02.40AB to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code History & ChangesHistory
Replacement S02.40AB replaces the following previously assigned code(s):
- S02.400B - Malar fracture unspecified, init encntr for open fracture
- S02.400B - Malar fracture, unspecified side, 7thB
Questions About S02.40ABOverview
What is the ICD-10 code for malar fracture, right side, initial encounter for open fracture?
The ICD-10-CM code for malar fracture, right side, initial encounter for open fracture is S02.40AB (sometimes written as S0240AB). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is S02.40AB (Malar fracture, right side) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report malar fracture, right side, initial encounter for open fracture on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character B in S02.40AB mean?
The final character B reports the initial encounter for an open fracture, in this case involving the malar fracture, right side.
What MS-DRG does S02.40AB group to?
When malar fracture, right side, initial encounter for open fracture is the principal diagnosis on an inpatient stay, it groups to MS-DRG 11, 12, 13, 157, 158, 159, 963, 964, 965, with relative weights from 0.7085 to 5.4541 depending on complications. Higher weights mean higher Medicare reimbursement.
Is S02.40AB a CC or MCC?
CMS lists S02.40AB as a CC (complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 459 closely related codes in its exclusion list.
What HCC is S02.40AB?
S02.40AB (malar fracture, right side, initial encounter for open fracture) maps to CMS-HCC Category 399 (Major Head Injury without Loss of Consciousness), commonly written as HCC 399, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2026. It mapped to HCC 167 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 S02.40AB risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, S02.40AB adds a risk adjustment factor of about 0.199 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.052 to 0.349 depending on the payment segment). A more severe related category (HCC 397 and HCC 398) supersedes it when both are reported. See the full factor table on the HCC 399 category page.
