ICD-10 Code F31: Bipolar Disorder Diagnosis & Coding Guide

Key Takeaways

F31 codes document current bipolar episode type and severity

Episode specifiers change as patient presentation shifts during treatment

Severity levels require documented clinical assessment findings

Psychotic features mandate separate coding from baseline mood symptoms

DSM-5 criteria establish minimum documentation thresholds for code selection

ICD-10 Bipolar Disorder Coding Overview

ICD-10-CM bipolar disorder codes document the patient’s current clinical presentation at the time of the encounter. The F31 code series captures bipolar I disorder, bipolar II disorder, and related mood conditions, with each code reflecting both the episode type (manic, depressed, mixed) and current severity level. Most practitioners treating bipolar disorder face coding decisions at every visit because episode-based classification requires you to update the diagnosis code whenever the patient’s mood state changes.

Bipolar disorder coding differs from most psychiatric diagnoses. A patient diagnosed with bipolar I disorder in 2024 might require F31.13 (bipolar disorder, current episode manic, severe) in January 2026, F31.4 (bipolar disorder, current episode depressed, severe) in March 2026, and F31.71 (bipolar disorder, in partial remission) by June 2026. The diagnosis remains bipolar disorder throughout, but the ICD-10-CM code shifts to match the documented episode type and severity at each encounter. Mental health EMR systems like Pabau’s mental health platform track these episode transitions within the patient record, flagging when prior codes no longer match current presentation.

The F31 series begins at F31.0 (bipolar disorder, current episode hypomanic) and extends through F31.9 (bipolar disorder, unspecified). Each code captures a specific combination of episode type, severity, and the presence or absence of psychotic features. Documentation requirements vary by code – a mild depressive episode demands different clinical evidence than a severe manic episode with psychotic features.

F31 Code Structure: Episode Types and Severity Specifiers

ICD-10-CM bipolar disorder codes follow a hierarchical structure. The first three characters (F31) identify bipolar disorder as the diagnostic category. The fourth character specifies the current episode type. The fifth character, when present, indicates severity or the presence of psychotic features.

ICD-10 Bipolar Disorder Code F31.0: Current Episode Hypomanic

F31.0 documents bipolar disorder when the patient currently meets criteria for a hypomanic episode. Hypomania requires elevated or irritable mood lasting at least four consecutive days, with observable changes in functioning that do not cause marked impairment. This code appears most frequently in bipolar II disorder documentation, where hypomanic episodes alternate with major depressive episodes. Billing with F31.0 requires charting specific symptoms (inflated self-esteem, decreased need for sleep, increased goal-directed activity) that distinguish hypomania from baseline mood or subsyndromal symptoms.

ICD-10 Bipolar 1 Code F31.1x: Current Episode Manic

Manic episodes divide into four severity codes. F31.10 (bipolar disorder, current episode manic without psychotic features, unspecified) serves as a placeholder when severity documentation is incomplete. F31.11 captures mild mania – elevated mood with minimal functional impairment. F31.12 reflects moderate mania causing noticeable occupational or social disruption. F31.13 documents severe mania without psychotic features, typically requiring intensive outpatient monitoring or brief hospitalisation.

When manic symptoms escalate to include delusions or hallucinations, the code shifts to F31.2 (bipolar disorder, current episode manic, severe with psychotic features). This distinction matters for treatment planning and insurance authorisation. A patient coded F31.13 on Monday who develops grandiose delusions by Thursday requires recoding to F31.2 at the next encounter, even if the visit occurs only three days later. AI-powered clinical documentation tools can flag symptom patterns that suggest a severity upgrade is warranted.

ICD-10 Bipolar Disorder Code F31.3x-F31.5: Current Episode Depressed

Depressive episodes in bipolar disorder follow the same severity hierarchy as unipolar depression but carry distinct treatment implications. F31.30 (bipolar disorder, current episode depressed, mild or moderate severity, unspecified) applies when documentation lacks specific severity indicators. F31.31 codes mild depressive episodes – symptoms present but causing minimal impairment. F31.32 reflects moderate severity with noticeable functional decline.

Severe depressive episodes split based on psychotic features. F31.4 documents severe depression without psychosis. F31.5 captures severe depression with mood-congruent or mood-incongruent delusions or hallucinations. Many clinics mistakenly use F31.4 for any significant depressive episode, missing the coding requirement to upgrade to F31.5 when psychotic symptoms appear. This error reduces reimbursement for higher-acuity care and understates the patient’s clinical complexity in claims data.

F31.6x: Mixed Episode Specifiers

Mixed episodes combine manic and depressive symptoms simultaneously. F31.60 (bipolar disorder, current episode mixed, unspecified) serves as a default when severity is unclear. F31.61, F31.62, F31.63, and F31.64 follow the mild-moderate-severe-psychotic hierarchy seen in pure manic or depressive episodes. Mixed presentations often confound new clinicians because symptom clusters fluctuate rapidly within a single day. The WHO ICD-10 browser defines mixed episodes as periods where both manic and depressive criteria are met nearly every day for at least one week.

F31.7x: Bipolar Disorder in Remission

Remission codes document periods when the patient no longer meets full criteria for a mood episode. F31.71 (bipolar disorder, in partial remission) applies when some symptoms persist but do not reach episode thresholds. F31.72 (bipolar disorder, in full remission) indicates symptom resolution, though the bipolar disorder diagnosis remains active because the condition carries a chronic course with high relapse risk. Many practitioners overlook these codes, continuing to bill acute episode codes even when patients have stabilised. Accurate remission coding matters for treatment step-down decisions and demonstrates clinical progress in outcomes tracking.

F31.9: Bipolar Disorder Unspecified

F31.9 codes bipolar disorder when episode type or severity cannot be determined from available documentation. This unspecified code appears in three scenarios: initial diagnostic workups before full episode characterisation, coding errors when the chart lacks episode descriptors, and transitions between episodes where the patient’s presentation does not clearly fit manic, depressed, or mixed criteria. Frequent use of F31.9 in an established patient’s chart signals documentation gaps that may trigger payer audits.

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Documentation Requirements for ICD-10 Bipolar Disorder Coding

Each F31 code demands specific clinical observations in the encounter note. Vague language (“patient seems manic,” “mood is low”) does not satisfy coding guidelines. The CDC’s ICD-10-CM tool cross-references codes with DSM-5 criteria, establishing minimum documentation thresholds.

Severity determination requires explicit functional assessment. Mild episodes cause “slight” impairment in social or occupational functioning. Moderate episodes produce “moderate” difficulty maintaining work, relationships, or self-care. Severe episodes create “serious” impairment requiring significant support or hospitalisation. These are not subjective impressions – clinicians must document observable functional changes. A patient who missed three days of work due to depressive symptoms meets moderate severity criteria. A patient requiring psychiatric admission for safety concerns meets severe criteria. Charts lacking these functional anchors leave coding vulnerable to downgrades during utilisation review.

Psychotic features require separate symptom documentation. Delusions must be described (grandiose beliefs, paranoid ideation, somatic delusions). Hallucinations need modality specification (auditory, visual). Mood congruence matters – delusions consistent with the mood state (grandiose delusions during mania) code differently in some contexts than mood-incongruent psychosis (nihilistic delusions during mania). Mental health practices using structured digital intake forms prompt clinicians to capture these details during the psychiatric interview, reducing documentation gaps that lead to coding ambiguity.

Episode duration thresholds appear throughout F31 coding rules. Hypomanic episodes require four consecutive days of elevated mood. Manic and major depressive episodes require one week of sustained symptoms (or less if hospitalisation occurs). Mixed episodes demand one week of simultaneous manic and depressive criteria. Documentation must establish timeline. A patient reporting “feeling great for the past two days” does not support hypomania coding. A patient describing “can’t sleep, racing thoughts, extremely productive for five days straight” provides timeline evidence for F31.0.

Bipolar I vs Bipolar II: ICD-10 Coding Distinctions

ICD-10-CM does not include separate code series for bipolar I versus bipolar II disorder. Both conditions use F31 codes, with episode type determining the specific code rather than the underlying bipolar subtype. This contrasts with DSM-5, which distinguishes bipolar I (requiring at least one manic episode) from bipolar II (requiring at least one hypomanic episode plus at least one major depressive episode, but never a full manic episode).

The coding implication: a patient with bipolar II disorder currently experiencing a major depressive episode receives F31.31, F31.32, F31.4, or F31.5 depending on severity and psychotic features – the same codes used for bipolar I disorder during a depressive episode. The distinction lies in the patient’s longitudinal history. A chart note documenting “bipolar II disorder, current episode major depression, moderate severity” translates to F31.32. The bipolar II specification exists in the clinical narrative but does not change the ICD-10-CM code selection.

This creates documentation challenges. Coders reviewing a chart with code F31.12 cannot determine whether the patient has bipolar I or bipolar II disorder without reading the full psychiatric history. Some practices address this by maintaining bipolar subtype in a separate diagnosis field or problem list entry. Others rely on initial evaluation summaries that establish the bipolar subtype, then apply episode-based F31 codes at each subsequent encounter. Psychiatry EMR systems designed for mood disorder tracking often include bipolar subtype flags that persist across encounters while episode codes update.

Common ICD-10 Bipolar Disorder Coding Errors and How to Avoid Them

Coding errors in bipolar disorder documentation cluster around four patterns. First, practitioners continue using F31.9 (unspecified) in established patients despite having sufficient clinical information to specify episode type. This occurs when clinicians view ICD-10-CM codes as static labels rather than encounter-specific classifications. The patient may have bipolar disorder as a standing diagnosis, but each visit requires a code reflecting current presentation.

Second, severity upgrades get missed when symptoms worsen between appointments. A patient enters treatment with F31.31 (mild depressive episode), develops suicidal ideation over two weeks, but the code remains F31.31 at the next visit because the clinician focused on crisis intervention rather than diagnostic coding. Accurate coding requires real-time severity reassessment. Practices using integrated scheduling and clinical documentation can flag severity mismatches when appointment types (routine follow-up versus urgent evaluation) suggest higher acuity than the last-billed code.

Third, psychotic features documentation often lacks specificity. A chart note reading “patient experiencing auditory hallucinations” during a manic episode might get coded F31.13 (severe mania without psychosis) instead of F31.2 (severe mania with psychotic features) if the coder assumes “experiencing” means historical rather than current symptoms. Psychotic features coding demands present-tense symptom documentation: “Patient reports hearing voices commanding him to harm others today.” This temporal clarity prevents coding ambiguity.

Fourth, remission codes get underutilised. Many clinicians reflexively bill the last acute episode code even when patients have stabilised. A patient who presented with F31.4 (severe depression without psychosis) in November might warrant F31.71 (partial remission) by January if depressive symptoms have improved but subsyndromal mood instability persists. Continued use of acute codes inflates severity metrics in population health analytics and may trigger unnecessary prior authorisations for routine maintenance care.

Billing Workflows: Linking ICD-10 Bipolar Codes to CPT Codes

ICD-10-CM diagnosis codes support CPT procedure codes on mental health claims. Psychotherapy services (90832, 90834, 90837) pair with F31 codes to establish medical necessity. Psychiatric diagnostic evaluations (90791, 90792) link to bipolar disorder codes when the visit focuses on mood episode assessment. Medication management (99212-99215 or 90863) claims require an active F31 code demonstrating ongoing treatment need.

Payer policies vary on which F31 codes support which CPT codes. Most insurers accept any F31 code (except F31.9) for outpatient psychotherapy. Some restrict intensive services like partial hospitalisation programs to severe episode codes (F31.13, F31.2, F31.4, F31.5, F31.63, F31.64). Billing 90837 (psychotherapy, 53 minutes) with F31.31 (mild depression) may prompt a medical necessity review because 53-minute sessions typically address higher-acuity presentations. Clinics using claims management software can set diagnosis-procedure pairing rules that flag mismatches before claim submission.

Acute episode codes justify more frequent visits. A patient billed with F31.13 (severe mania) supports weekly psychotherapy. The same patient coded F31.71 (partial remission) three months later may face scrutiny for weekly sessions because remission implies decreased service intensity. Documentation must explain ongoing visit frequency – perhaps residual symptoms requiring close monitoring, medication adjustments, or psychosocial stressors increasing relapse risk. The diagnosis code alone does not tell the full story, but it establishes the baseline clinical acuity from which treatment intensity decisions flow.

Some mental health billing scenarios require multiple diagnosis codes. A patient with bipolar disorder and comorbid anxiety might carry F31.32 (bipolar, current episode moderate depression) as the primary code and F41.1 (generalised anxiety disorder) as a secondary code. The order matters – the primary code justifies the encounter’s main focus. If the visit addressed anxiety coping strategies more than mood stabilisation, F41.1 should be primary. Coding guidelines from the Centers for Medicare & Medicaid Services specify that the diagnosis chiefly responsible for services rendered should appear first on the claim.

DSM-5 to ICD-10 Bipolar Disorder Crosswalk

DSM-5 establishes clinical diagnostic criteria. ICD-10-CM translates those criteria into billable codes. The two systems overlap but diverge in structure. DSM-5 bipolar disorder criteria span pages of detailed specifiers (with anxious distress, with mixed features, with rapid cycling, with peripartum onset). ICD-10-CM collapses these specifiers into a simpler episode-type-and-severity framework.

A patient meeting DSM-5 criteria for bipolar I disorder, current episode manic, severe, with psychotic features, with anxious distress, with rapid cycling, maps to ICD-10-CM code F31.2. The ICD-10-CM code captures “severe manic episode with psychotic features” but does not code the anxious distress or rapid cycling specifiers. Those clinical details belong in the narrative documentation, influencing treatment planning, but they do not change the billable diagnosis code. This simplification frustrates clinicians who view ICD-10-CM as too coarse-grained for complex mood presentations, yet billing systems require the condensed code structure.

The practical workflow: conduct your psychiatric evaluation using DSM-5 criteria, document all relevant specifiers in the assessment narrative, then select the ICD-10-CM code that best matches the current episode type and severity. The full DSM-5 diagnosis (“Bipolar I Disorder, Most Recent Episode Manic, Severe, with Psychotic Features, with Anxious Distress”) remains in your clinical formulation. The billing diagnosis code (F31.2) captures the core syndromal presentation. The narrative bridges the two by explaining why F31.2 is the correct code given the documented symptom pattern.

Some EMR systems store DSM-5 specifiers as discrete data fields separate from ICD-10-CM codes. This structure allows clinical decision support tools to flag patients with high-risk specifiers (psychotic features, rapid cycling) while maintaining clean ICD-10-CM coding for claims submission. Mental health practices evaluating practice management software should confirm the platform supports this dual-layer diagnostic architecture rather than forcing DSM-5 specifiers into free-text fields where they cannot drive automated alerts.

Special Coding Scenarios: Rapid Cycling, Peripartum Onset, Seasonal Patterns

ICD-10-CM lacks specific codes for many clinically significant bipolar disorder specifiers. Rapid cycling (four or more mood episodes per year) has no unique code. Peripartum onset (episode occurring during pregnancy or within four weeks postpartum) has no F31 variant. Seasonal pattern (regular temporal relationship between mood episodes and time of year) remains uncoded.

Clinicians handle these scenarios through documentation layering. Code the current episode using standard F31 codes, then document the specifier in the assessment narrative and problem list. A patient with bipolar disorder, current episode depressed, moderate, with seasonal pattern, receives F31.32 on the claim. The encounter note states: “Bipolar I disorder, current episode major depression, moderate severity, with seasonal pattern (winter onset for past three years). Patient reports symptom onset in November, improvement by April annually.” This approach preserves clinical nuance while maintaining billing code simplicity.

Some practices use supplementary diagnosis codes when additional clinical context affects treatment. A patient with peripartum onset bipolar depression might warrant both F31.32 (bipolar, current episode moderate depression) and O99.34 (mental disorders complicating pregnancy, childbirth, and the puerperium). The obstetric complication code signals payers that pregnancy-related factors influence treatment planning, potentially supporting coverage for more intensive monitoring. Check payer-specific guidelines before adding supplementary codes, as some insurers reject claims with multiple psychiatric diagnoses unless medical necessity documentation clearly justifies each code.

When to Use F30 (Manic Episode) vs F31 (Bipolar Disorder)

F30 codes document manic episodes occurring as the sole presentation, typically during initial evaluation before establishing a bipolar disorder diagnosis. F30.10 (manic episode without psychotic symptoms, unspecified), F30.11 (mild), F30.12 (moderate), and F30.13 (severe) apply when the patient presents with a first manic episode and no prior history of depression or hypomania.

The distinction matters clinically and administratively. A 23-year-old patient experiencing his first manic episode might receive F30.13 if no depressive episode history exists. Three months later, after the manic symptoms resolve and a historical review reveals prior untreated depressive episodes, the diagnosis shifts to bipolar I disorder. Future encounters code with F31 series regardless of whether the patient is currently manic, depressed, mixed, or in remission. F30 codes represent single episodes before longitudinal pattern recognition establishes the bipolar disorder diagnosis. F31 codes document bipolar disorder once the recurrent mood disturbance pattern is clear.

Most established patients with bipolar disorder should never receive F30 codes. A patient previously diagnosed with bipolar I disorder who presents with a new manic episode gets F31.12, F31.13, or F31.2 depending on severity – not F30.13. The bipolar disorder diagnosis persists regardless of current episode status. Exception: some coders use F30 codes when a patient with bipolar disorder develops a manic episode that prompts inpatient hospitalisation, then switch to F31 codes upon discharge. This practice varies by facility coding guidelines. Confirm your local conventions before alternating between F30 and F31 series for the same patient.

Differentiating Schizoaffective Disorder from Bipolar with Psychotic Features

Schizoaffective disorder (F25.0 for bipolar type, F25.1 for depressive type) and bipolar disorder with psychotic features (F31.2, F31.5, F31.64) share overlapping presentations but require different coding. The distinction hinges on psychotic symptom timing relative to mood episodes.

Bipolar disorder with psychotic features codes when hallucinations or delusions occur exclusively during mood episodes. A patient with F31.2 (severe mania with psychosis) experiences delusions only when manic symptoms are active. Once the manic episode remits, psychotic symptoms resolve. If delusions persist after mood stabilisation, reconsider the diagnosis – ongoing psychosis suggests schizoaffective disorder rather than bipolar disorder with psychotic features.

Schizoaffective disorder codes when psychotic symptoms persist for at least two weeks in the absence of major mood episodes. A patient meeting criteria for schizoaffective disorder, bipolar type (F25.0) exhibits manic and depressive episodes plus schizophrenia-spectrum symptoms (hallucinations, delusions, disorganised thinking) that continue during euthymic periods. This longitudinal pattern distinguishes schizoaffective disorder from bipolar disorder with mood-congruent psychotic features.

Documentation for differential diagnosis must establish psychotic symptom timeline. Chart notes should specify: “Auditory hallucinations present during current manic episode, no history of hallucinations during euthymic periods” (supports F31.2) versus “Auditory hallucinations persisting for three weeks after manic episode resolved, continuing despite mood stabilisation” (supports F25.0). Ambiguous documentation leads to coding disputes and claim denials. Mental health practices should train clinicians to document symptom chronology explicitly rather than assuming coders can infer the temporal relationship from general symptom descriptions. Resources like the AMA’s coding resources provide differential diagnosis coding guidance when symptom presentations overlap.

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Conclusion: Accurate ICD-10 Bipolar Coding Supports Clinical and Financial Outcomes

Bipolar disorder coding accuracy rests on three foundations: understanding that F31 codes reflect current episode presentation rather than static diagnosis labels, documenting severity through functional assessment rather than subjective impression, and linking diagnosis codes to appropriate procedure codes that match documented service intensity. Practitioners who view coding as a clinical responsibility rather than an administrative afterthought produce charts that support both quality care and revenue integrity.

The most common coding failures stem from neglecting to update F31 codes as patients transition between mood episodes. A chart review finding the same diagnosis code billed across six months despite documented symptom fluctuations signals either coding error or inadequate clinical monitoring. Either interpretation creates liability. Accurate bipolar disorder coding requires ongoing reassessment – each encounter warrants asking whether the current code still matches the patient’s presentation or whether severity changes mandate a different F31 code.

Mental health practices benefit from building coding accuracy checks into standard workflows. Flag charts where the last-billed F31 code is more than 60 days old without documentation explicitly confirming episode stability. Review claims where diagnosis codes and procedure codes mismatch typical pairings (90837 billed with F31.9, F31.4 billed with routine 15-minute med checks). Train clinical staff to recognise when symptom changes require code updates before the next billing cycle. These operational adjustments reduce claim denials, improve population health analytics accuracy, and ensure documentation supports the clinical story treatment decisions reflect. Reviewed against current ICD-10-CM Official Guidelines for Coding and Reporting and DSM-5 diagnostic criteria.

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