ICD-10 Code F31.31 – Bipolar disorder, current episode depressed, mild (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code F31.31 – Bipolar disorder, current episode depressed, mild
What it is
This code identifies bipolar disorder with the patient currently in a depressive episode that is mild in severity. Use it when documentation clearly states bipolar depression and the depressive symptoms are not severe.
Clinical signs
Typical findings include low mood, reduced interest, fatigue, and other depressive symptoms, with a history of bipolar disorder. Clinical features vary; refer to documentation.
When to use this code
Use this code when the provider documents bipolar disorder, current episode depressed, mild, or equivalent wording. It is appropriate when the note specifies the current episode and its mild severity. Check documentation if the record does not clearly identify the episode type or severity.
Do not use for
Do not use this code for bipolar disorder without a current depressed episode, or when the episode is manic, mixed, or unspecified. Do not assume mild severity unless the documentation supports it.
Coding tip
Match the code to the documented current episode and severity exactly; if either is unclear, check documentation.