FY2027 ICD-10-CM reference
F05: Delirium due to known physiological condition
By the HCC Buddy Coding Team
The official ICD-10-CM descriptor is Delirium due to known physiological condition. The FY2027 annual edition starts October 1, 2026. Check the edition that applies to the encounter or inpatient discharge, including any April update.
Billable code. Verified against the official FY2027 order file.
FY2027 Tabular instructions
Instructions below include applicable chapter, section and parent-code notes. Each note identifies where it appears in the official source.
Includes
disorders of psychological development
Source: F01-F99 (chapter, inherited).
Excludes2
symptoms, signs and abnormal clinical laboratory findings, not elsewhere classified (R00-R99)
Source: F01-F99 (chapter, inherited).
Instructional note
This block comprises a range of mental disorders grouped together on the basis of their having in common a demonstrable etiology in cerebral disease, brain injury, or other insult leading to cerebral dysfunction. The dysfunction may be primary, as in diseases, injuries, and insults that affect the brain directly and selectively; or secondary, as in systemic diseases and disorders that attack the brain only as one of the multiple organs or systems of the body that are involved.
Source: F01-F09 (section, inherited).
Instructional note
Acute or subacute brain syndrome
Source: F05 (category, direct).
Instructional note
Acute or subacute confusional state (nonalcoholic)
Source: F05 (category, direct).
Instructional note
Acute or subacute infective psychosis
Source: F05 (category, direct).
Instructional note
Acute or subacute organic reaction
Source: F05 (category, direct).
Instructional note
Acute or subacute psycho-organic syndrome
Source: F05 (category, direct).
Instructional note
Delirium of mixed etiology
Source: F05 (category, direct).
Instructional note
Delirium superimposed on dementia
Source: F05 (category, direct).
Instructional note
Sundowning
Source: F05 (category, direct).
Code first
the underlying physiological condition, such as:
Source: F05 (category, direct).
Code first
dementia (F03.9-)
Source: F05 (category, direct).
Excludes1
delirium NOS (R41.0)
Source: F05 (category, direct).
Excludes2
delirium tremens alcohol-induced or unspecified (F10.231, F10.921)
Source: F05 (category, direct).
Compare the FY2027 additions, removals and billable-status changes
What does F05 mean in FY2027?
The official ICD-10-CM descriptor is Delirium due to known physiological condition. The FY2027 annual edition starts October 1, 2026. Check the edition that applies to the encounter or inpatient discharge, including any April update.
Is F05 billable in FY2027?
The FY2027 order file marks F05 as billable. Check the complete Tabular instructions and documentation before assigning it.
Does F05 map to an HCC?
F05 has no CMS-HCC V28 category in the CMS 2027 Initial ICD-10-CM Mappings (payment year 2027, 2026 dates of service). ESRD, RxHCC, PACE and HHS-HCC mappings are still pending verification for FY2027.
Source: CMS FY2027 ICD-10-CM order file. Read the FY2027 Official Guidelines.
Review the FY2026 April edition