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ICD-10-CM 2027 diagnosis code

B99Other and unspecified infectious diseases

Not billable — use a more specific code

B99 is a header code, so it can't be reported by itself. Choose one of the 2 more specific codes beneath it.

Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS, effective October 1, 2026. Updated September 29, 2026. About our data

About B99

B99 is the ICD-10-CM diagnosis code for other and unspecified infectious diseases. It belongs to block B99 (other infectious diseases) and chapter 1 (certain infectious and parasitic diseases). It is a header code, so it can't be reported by itself; one of its 2 subcodes must be used instead.

To report this condition, pick the subcode that matches the documentation: B99.8 (disease) and B99.9 (disease).

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

Specific codes under B99

Notes that apply from higher levels

Instructions written at a parent level also apply to B99.

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

Alphabetic index entries

11 entries

Terms in the official ICD-10-CM index that lead to B99.

Codes whose notes reference B99

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 B99

Is B99 billable?

No. B99 is a header code. Report one of its more specific subcodes instead.