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ICD-10-CM 2027 diagnosis code

B03Smallpox

✓ Billable / specificCC — complication/comorbidity

B03 is a valid, billable ICD-10-CM code for smallpox. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Looking up by condition? See ICD-10 code for Variola, ICD-10 code for Alastrim, ICD-10 code for Smallpox, ICD-10 code for Varioloid.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About B03

B03 is the ICD-10-CM diagnosis code for smallpox. It belongs to block B00-B09 (viral infections characterized by skin and mucous membrane lesions) and chapter 1 (certain infectious and parasitic diseases). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 865 (Viral Illness with MCC, relative weight 1.3485) and DRG 866 (Viral Illness without MCC, relative weight 0.8692), in MDC 18 (Infectious and Parasitic Diseases, Systemic or Unspecified Sites), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 050.0 (Variola major), 050.1 (Alastrim) and 050.9 (smallpox, unspecified).

Coding notes

Note
  • In 1980 the 33rd World Health Assembly declared that smallpox had been eradicated.
  • The classification is maintained for surveillance purposes.

Notes that apply from higher levels

Instructions written at a parent level also apply to B03.

Broader instructions also apply from Chapter 1: Certain infectious and parasitic diseases.

Alphabetic index entries

4 entries

Terms in the official ICD-10-CM index that lead to B03.

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

MDC 18 · Infectious and Parasitic Diseases, Systemic or Unspecified Sites

ICD-9-CM equivalent

Converter →
  • 050.0Variola majorapproximate
  • 050.1Alastrimapproximate
  • 050.9Smallpox, unspecifiedapproximate

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about B03

Is B03 billable?

Yes. B03 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can B03 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict B03 as a principal diagnosis.

Is B03 a CC or MCC?

B03 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.

What DRG does B03 group to?

B03 is used in the MS-DRG v44.0 logic for MS-DRG 865 (Viral Illness with MCC) and MS-DRG 866 (Viral Illness without MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.

What is the ICD-9 code for B03?

The CMS General Equivalence Mappings map B03 to ICD-9-CM 050.0, 050.1 and 050.9.