2026 ICD-10-CM Diagnosis Code Z86.51Personal history of combat and operational stress reaction

ICD-10-CM Codes›Z00–Z99›Z77-Z99›Z86

ICD-10-CM Z86.51
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

Z86.51 is a billable ICD-10-CM diagnosis code for personal history of combat and operational stress reaction. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). The code is restricted by the Medicare Code Editor to adult patients (age 15 through 124), not accepted as a principal diagnosis, and exempt from POA reporting. Coders also document this condition as history of combat and operational stress reaction. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Personal history of other disease.

Code Identity

ICD-10-CM Code
Z86.51
Billable Status
Yes — Valid for Submission
Code Describes
Personal history of combat and operational stress reaction
Short Description
Personal history of combat and operational stress reaction
Same as the full description in the CMS dataset.
Parent Code
Z86.5
Personal history of mental and behavioral disorders

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
CategoryZ86Personal history of certain other diseases
This CodeZ86.51Personal history of combat and operational stress reaction

Code EditsBilling

Medicare Code Editor checks that affect claim validity for Z86.51.

Adult diagnoses
The Medicare Code Editor detects inconsistencies in adult cases by checking a patient's age and any diagnosis on the patient's record. The adult code edits apply to patients age range is 15–124 years inclusive (e.g., senile delirium, mature cataract).
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

Z86.51 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • History of combat and operational stress reaction

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.

    • History
      • personal (of)
        • combat and operational stress reaction

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR FAC030
Personal history of other disease
Default principal diagnosis: inpatient No · outpatient Yes

Patient EducationClinical

Post-Traumatic Stress Disorder

Post-traumatic stress disorder (PTSD) is a mental health disorder that some people develop after they experience or see a traumatic event. The traumatic event may be life-threatening, such as combat, a natural disaster, a car accident, or sexual assault. But sometimes the event is not necessarily a dangerous one.

The full article covers:

  • What is post-traumatic stress disorder (PTSD)?
  • What causes post-traumatic stress disorder (PTSD)?
  • Who is more likely to develop post-traumatic stress disorder (PTSD)?
  • What are the symptoms of post-traumatic stress disorder (PTSD)?
  • How is post-traumatic stress disorder (PTSD) diagnosed?
  • What are the treatments for post-traumatic stress disorder (PTSD)?
  • Can post-traumatic stress disorder (PTSD) be prevented?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert Z86.51 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
V11.4 Hx combat/stress reactn
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About Z86.51Overview

Is Z86.51 (Personal history of mental and behavioral disorders) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report personal history of combat and operational stress reaction on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Can Z86.51 be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because personal history of combat and operational stress reaction describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.

Who can Z86.51 be reported for?

The Medicare Code Editor checks personal history of combat and operational stress reaction against patient demographics: this code is intended for adult patients (age 15 through 124). Claims outside these limits are flagged as inconsistent.

Is Z86.51 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 personal history of combat and operational stress reaction on inpatient claims.

What is the ICD-9 equivalent of Z86.51?

Under the General Equivalence Mappings, personal history of combat and operational stress reaction converts to ICD-9-CM V11.4 (hx combat/stress reactn). The mapping is a direct match.