2026 ICD-10-CM Diagnosis Code Z77.31Contact with and (suspected) exposure to Gulf War theater

ICD-10-CM Codes›Z00–Z99›Z77-Z99›suspected

ICD-10-CM Z77.31
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

Z77.31 is a billable ICD-10-CM diagnosis code for contact with and (suspected) exposure to Gulf War theater. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). The code is not accepted as a principal diagnosis by the Medicare Code Editor and exempt from POA reporting.

Code Identity

ICD-10-CM Code
Z77.31
Billable Status
Yes — Valid for Submission
Code Describes
Contact with and (suspected) exposure to Gulf War theater
Short Description
Contact with and (suspected) exposure to Gulf War theater
Same as the full description in the CMS dataset.
Parent Code
Z77.3
Contact with and (suspected) exposure to war theater

Code Classification

ChapterZ00–Z99Factors influencing health status and contact with health services
SectionZ77-Z99Persons with potential health hazards related to family and personal history and certain conditions influencing health status
CategorysuspectedOther contact with and exposures hazardous to health (Z77)
This CodeZ77.31Contact with and (suspected) exposure to Gulf War theater

Code EditsBilling

Medicare Code Editor checks that affect claim validity for Z77.31.

Unacceptable principal diagnosis
There are selected codes that describe a circumstance which influences an individual's health status but not a current illness or injury, or codes that are not specific manifestations but may be due to an underlying cause. These codes are considered unacceptable as a principal diagnosis.

Present on Admission (POA)Billing

Z77.31 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Contact with and (suspected) exposure to Persian Gulf War theater

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Contact(with)
      • war theater (Gulf) (Persian Gulf)

Code History & ChangesHistory

New Code Z77.31 was added to the ICD-10-CM code set for FY 2026, effective October 1, 2025.

Replacement Z77.31 replaces the following previously assigned code(s):

  • Z77.3 - Contact with and (suspected) exposure to war theater
FY 2026AddedAdded to the ICD-10-CM code setEffective October 1, 2025.
FY 2026CurrentRevised in the current code setEffective October 1, 2025 through September 30, 2026.

Questions About Z77.31Overview

Is Z77.31 (Contact with and (suspected) exposure to war theater) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report contact with and (suspected) exposure to Gulf War theater on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Can Z77.31 be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because contact with and (suspected) exposure to Gulf War theater describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.

Is Z77.31 exempt from POA reporting?

Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for contact with and (suspected) exposure to Gulf War theater on inpatient claims.