ICD-10 Code F31.81 – Bipolar II disorder (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code F31.81 – Bipolar II disorder
What it is
Bipolar II disorder is a mood disorder marked by recurring depressive episodes and at least one hypomanic episode. You use this code when the record identifies Bipolar II disorder specifically.
Clinical signs
Clinical features include periods of elevated or irritable mood, increased energy, and reduced need for sleep, but without full mania. Depressive episodes are common; clinical features vary, so refer to documentation.
When to use this code
Use F31.81 when the provider documents Bipolar II disorder, bipolar II affective disorder, or a similar confirmed diagnosis. Apply it for encounters focused on mood symptoms, psychiatric follow-up, or assessment of ongoing bipolar illness. Check documentation if the note does not clearly distinguish Bipolar II from other bipolar types.
Do not use for
Do not use this code for bipolar I disorder, cyclothymic disorder, or major depressive disorder without hypomania. If the diagnosis is uncertain or unspecified, check documentation and code the documented condition.
Coding tip
Confirm that the chart documents hypomania and not mania before assigning F31.81.