B04 — Monkeypox
Is B04 billable?
Yes — B04 is billable for FY2027. B04 is a valid, billable ICD-10-CM code at the highest level of specificity in its branch. B04 may be submitted for encounters from October 1, 2026 through September 30, 2027.
B04 at a glance
| Code | B04 |
|---|---|
| Description | Monkeypox |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
Which MS-DRGs does B04 group to?
B04 sits in MDC 18 and helps define the logic of 2 MS-DRGs (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.
- 865Viral Illness with MCCmedical
- 866Viral Illness without MCCmedical
As a secondary diagnosis, B04 is a complication or comorbidity (CC), which can move a stay into a higher-paying DRG.
How is B04 listed in the Alphabetic Index?
These are the routes through the Alphabetic Index that lead to B04. They show the wording a clinician may have documented, which often differs from the Tabular description.
- Monkeypox
- Mpox
Inclusion terms
Alternative wording in documentation that is classified to B04.
- Mpox
Use additional code — inherited from Chapter 1
Report an additional code alongside B04 to fully describe the condition. B04 is sequenced first.
- code to identify resistance to antimicrobial drugs (Z16.-)
Excludes2 — not included here — inherited from Chapter 1
The conditions below are not part of B04, but a patient may have both at the same time. When documentation supports it, B04 and the excluded code may both be reported.
- carrier or suspected carrier of infectious disease (Z22.-)
- certain localized infections - see body system-related chapters
- infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)
- infectious and parasitic diseases specific to the perinatal period (P35-P39)
- influenza and other acute respiratory infections (J00-J22)
How long has B04 existed?
B04 has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.