Is ICD-10-CM code W99 billable?

No, W99 (Exposure to other man-made environmental factors) is a non-billable ICD-10-CM code. It must be coded to a more specific subcategory before it can be used for reimbursement.

What chapter does ICD-10-CM code W99 belong to?

W99 belongs to Chapter 20 of the ICD-10-CM tabular list: V00–Y99 (External Causes of Morbidity).

W99Not billable, use a more specific code below

Exposure to other man-made environmental factors

In Exposure to electric current, radiation and extreme ambient air temperature and pressure (W85-W99), chapter 20: External Causes of Morbidity

3 billable codes under W99: none are a CC or MCC; none map to an HCC.

Instructional notes

Also applies, from Exposure to electric current, radiation and extreme ambient air temperature and pressure (W85-W99)

These notes sit on W85-W99 and apply to every code under it, including W99.

Excludes1: not coded here, use a different code

exposure to:
failure in dosage of radiation or temperature during surgical and medical care (Y63.2-Y63.5)
lightning (T75.0-)
natural cold (X31)
natural heat (X30)
natural radiation NOS (X39)
radiological procedure and radiotherapy (Y84.2)
sunlight (X32)

Official coding guidelines

From the ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027 (CMS and NCHS). Links open the PDF at the right page.

Covers how to report external cause codes (V00-Y99) describing cause, intent, place, activity, and status. They are never principal or first-listed, and reporting is voluntary unless required.

General External Cause Coding Guidelines (page 88)
Place of Occurrence Guideline (page 89)
Activity Code (page 89)
Place of Occurrence, Activity, and Status Codes Used with other External Cause Code (page 89)
If the Reporting Format Limits the Number of External Cause Codes (page 90)
Multiple External Cause Coding Guidelines (page 90)
Child and Adult Abuse Guideline (page 90)
Unknown or Undetermined Intent Guideline (page 91)

Read Section I.C.20 (page 87), 3 more topics

All codes under W99

W99 can't be used on a claim. Pick a billable code below; grey headings group them.

W99 MS-DRGs

This code does not group to an MS-DRG as a principal diagnosis.

Code history

Valid since FY2016, when ICD-10-CM took effect on October 1, 2015. No changes since.