G31 › G31.8

G31.84 Mild cognitive impairment of uncertain or unknown etiology

BillableNo payment HCCChapter 6

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Instructional notes

Chapter 6

Excludes2Not included here: the patient may have both; report both when both are present.

certain conditions originating in the perinatal period (P04-P96)
certain infectious and parasitic diseases (A00-B99)
complications of pregnancy, childbirth and the puerperium (O00-O9A)
congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
endocrine, nutritional and metabolic diseases (E00-E88)
injury, poisoning and certain other consequences of external causes (S00-T88)
neoplasms (C00-D49)
symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

G31

Excludes2Not included here: the patient may have both; report both when both are present.

Reye's syndrome (G93.7)

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code, if applicable, for codes G31.0-G31.83, G31.85-G31.9, to identify:
dementia with anxiety (F02.84, F02.A4, F02.B4, F02.C4)
dementia with behavioral disturbance (F02.81-, F02.A1-, F02.B1-, F02.C1-)
dementia with mood disturbance (F02.83, F02.A3, F02.B3, F02.C3)
dementia with psychotic disturbance (F02.82, F02.A2, F02.B2, F02.C2)
dementia without behavioral disturbance (F02.80, F02.A0, F02.B0, F02.C0)
mild neurocognitive disorder due to known physiological condition (F06.7-)

This code

Excludes1Not coded here: never report with this code, except when the two conditions are unrelated.

age related cognitive decline (R41.81)
altered mental status (R41.82)
cerebral degeneration (G31.9)
cerebrovascular diseases (I60-I69)
change in mental status (R41.82)
cognitive deficits following (sequelae of) cerebral hemorrhage or infarction (I69.01-, I69.11-, I69.21-, I69.31-, I69.81-, I69.91-)
cognitive impairment due to intracranial or head injury (S06.-)
dementia (F01.-, F02.-, F03.-)
mild neurocognitive disorder due to a known physiological condition (F06.7-)
neurologic neglect syndrome (R41.4)
personality change, nonpsychotic (F68.8)

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code to identify presence of:
alcohol abuse and dependence (F10.-)
exposure to environmental tobacco smoke (Z77.22)
history of tobacco dependence (Z87.891)
hypertension (I10-I1A)
occupational exposure to environmental tobacco smoke (Z57.31)
tobacco dependence (F17.-)
tobacco use (Z72.0)

Inclusion terms

Mild cognitive disorder NOS
Mild neurocognitive disorder of uncertain or unknown etiology

Chapter 6: Diseases of the nervous system · G30-G32 Other degenerative diseases of the nervous system (G30-G32)

Source: ICD-10-CM FY 2027 code descriptions and tabular list (CMS and CDC National Center for Health Statistics), effective 2026-10-01 through 2027-09-30 · CMS ICD-10 files. HCC mapping: CMS-HCC V28, payment year 2027. As of 2026-11-04.

Coverage and payment depend on the claim details; confirm with the Medicare Administrative Contractor.