ICD 10 Bipolar Disorder: 2026 ICD-10-CM Diagnosis Code (F31) and Coding Revision Guide

The classification framework of the ICD‑10‑CM plays a vital role in the understanding, documentation, and treatment of Bipolar disorder. Accurate use of a standardized diagnosis code ensures clarity in clinical communication, helps guide treatment decisions, and supports appropriate insurance processing. At the heart of this system is the code Bipolar disorder code F31 (for example: F31.0, F31.81) and related sub-codes, which capture the condition’s varied presentations across mood states and severity levels. 

This guide is structured to help practitioners, coders, and behavioural health professionals navigate the complex terrain of bipolar disorder’s diagnosis and classification using ICD-10-CM. We begin with an overview of what bipolar disorder is and how it affects individuals and systems of care. From there, we will explore the structure and significance of the ICD-10 system, particularly as it applies to bipolar disorder. Then we will locate and interpret the specific 2026 ICD-10-CM diagnosis codes for bipolar disorder and examine how these codes influence treatment pathways, documentation practices, and reimbursement models. We will also consider diagnostic challenges and future directions for classification and coding.

By carefully aligning clinical presentation with the correct diagnosis code — including understanding specifiers, remission status, and episode type — professionals can enhance care accuracy, streamline documentation, and support optimal outcomes. With that foundation, we now proceed to the section “Understanding Bipolar Disorder – What Is Bipolar Disorder?” where we will define the condition, explore its key features, and set the stage for the coding and classification work ahead.

Understanding the Major Depressive Bipolar Disorder

What is Bipolar Disorder?

Bipolar disorder is an affective illness marked by episodes of abnormally elevated mood and energy alternating with episodes of depression. Clinically, these fluctuations are more extreme than normal mood variation and cause measurable impairment in social or occupational functioning, or require hospitalization for safety. Diagnostic frameworks (DSM-5; clinical guidelines summarized by agencies such as the National Institute of Mental Health) emphasize episodic changes in mood, energy, sleep, and activity that form recognizable syndromes rather than transient mood changes. Neurobiological research supports that bipolar presentations reflect alterations in neural circuits and neurotransmitter systems, though no single biological marker is diagnostic.

What are the Different Types of Bipolar Disorder?

Contemporary diagnostic systems distinguish several principal categories:

• Bipolar I disorder — defined by the presence of at least one manic episode; manic states are discrete periods (typically ≥1 week unless hospitalization is required) of persistently elevated, expansive, or irritable mood with increased goal-directed activity or energy and additional symptoms such as pressured speech, decreased need for sleep, grandiosity, and risky behavior. Manic episodes often produce clear functional impairment. 
• Bipolar II disorder — characterized by recurrent depressive episodes and hypomanic episodes (less severe than mania and not causing marked functional impairment). Importantly, Bipolar II patients do not meet criteria for full mania; depressive episodes in Bipolar II can be long and disabling. 
• Cyclothymic disorder — a chronic, milder course involving numerous periods of hypomanic symptoms and depressive symptoms that do not meet full episode criteria; symptoms must persist for at least two years in adults.
• Other and unspecified bipolar spectrum presentations — presentations that do not fit the above categories but show clinically significant mood instability.

Clinicians also document specifiers to describe current mood state (e.g., depressed, manic, hypomanic), presence or absence of psychotic features, and whether the patient is in remission.

What Causes Bipolar Disorder?

Bipolar disorder arises from a complex interplay of genetic, neurobiological, and environmental factors:

• Genetic liability: Family and twin studies show high heritability; relatives of affected individuals have increased risk compared with the general population. Genetic studies implicate multiple risk loci rather than a single “bipolar gene.” 
• Neurobiology: Structural and functional neuroimaging studies identify differences in limbic circuits and prefrontal regions involved in emotion regulation. Neurochemical hypotheses emphasize dysregulation in monoaminergic and glutamatergic systems; however, findings are heterogeneous and do not replace clinical assessment. 
• Psychosocial and environmental contributors: Stressful life events, substance use, sleep disruption, and early adversity can precipitate or exacerbate episodes in predisposed individuals. Chronobiological factors (e.g., circadian disruption) are increasingly recognized as modulators of episode onset. 

Importantly, the multifactorial aetiology explains why presentations vary widely between individuals and over time; this variability underpins the need for careful longitudinal assessment.

How Does Bipolar Disorder Affect Individuals?

The disorder has broad functional effects across domains:

• Daily functioning and work/school: During manic or hypomanic phases individuals may show impulsivity, poor judgment, or reduced sleep that disrupts work or school performance. During depressive phases, concentration, motivation, and energy may be so impaired that routine tasks become difficult. 
• Relationships and social functioning: Mood swings and behavioral changes can strain personal and family relationships; interpersonal conflicts are common during mood episodes.
• Comorbidity and risk: Anxiety disorders, substance use disorders, and medical comorbidities frequently co-occur. Bipolar disorder is associated with an increased risk of suicidal behavior, particularly during depressive or mixed episodes; suicide risk assessment is essential whenever depressive symptoms or hopelessness are present. 
• Long-term course: Some patients experience recurrent, episodic illness with partial recovery between episodes; others may have rapid cycling (four or more mood episodes in 12 months) or chronic residual symptoms that impair quality of life. Early onset (adolescence/young adulthood) often predicts a more complicated course. 

Clinical vignette (brief): A 28-year-old teacher is brought in by family after two weeks of decreased need for sleep, pressured speech, and impulsive spending that led to job problems. Collateral history reveals prior long periods of low mood with anergia and suicidal ideation. This longitudinal pattern (discrete elevated period plus prolonged depressive episodes) supports a diagnosis on the bipolar spectrum rather than unipolar depression and guides selection of mood-stabilizing treatments rather than antidepressant monotherapy.

Bipolar Disorder ICD-10 Classification System

What is the ICD-10 System?

The ICD-10 framework used in clinical practice (and its U.S. adaptation, ICD-10-CM) organizes diagnoses into chapters, blocks, and alphanumeric codes so that complex clinical presentations can be translated into standardized data. Mental and behavioral conditions appear in Chapter V (F00–F99), with mood [affective] disorders grouped in the F30–F39 block; within that block the entry F31 captures bipolar presentations and associated subtypes. The coding structure is intentionally hierarchical: a three-character category (e.g., F31) identifies the broad disorder, while four- and five-character subcodes (for example, F31.0, F31.10, F31.81) add detail about the current episode, severity, and presence of psychotic features. This granularity is essential for clinical documentation and downstream uses such as quality measurement and epidemiology. 

Key operational point: when clinicians document, “bipolar” alone is a starting concept — the medical record must support which subcode applies (current episode, severity, psychotic symptoms, remission status) so that the correct ICD-10-CM codes can be selected.

Why is ICD-10 Important for Mental Health Diagnosis?

ICD-10-CM codes are used across clinical systems, electronic health records, and claims platforms; they inform treatment pathways, populate problem lists, and enable population health analytics in behavioral health programs. For example, identifying a patient with F31.81 (Bipolar II disorder) in an EHR allows care teams to surface prior mood stabilizer trials, risk-assessment results, and suicide-prevention plans during visits. From an administrative perspective, codes also influence case mix, service authorization, and program eligibility (for instance, designation as a serious mental illness in some systems relies on diagnostic codes plus functional criteria). Accurate coding therefore links clinical decisions to system-level supports and resource allocation. 

Example: A community behavioral-health program using coded registries can stratify patients by subtype and episode (e.g., those coded F31.1 — current manic episode without psychotic features — may need urgent safety planning and medication review) and measure outcomes across subgroups.

How Does ICD-10 Differ from Previous Versions?

Compared with ICD-9, ICD-10-CM provides markedly greater specificity for mood disorders: clinicians can code the exact current episode (hypomanic, manic, depressed), indicate psychotic features, and in many cases document severity. This increase in detail improves clinical surveillance and enables more nuanced research, but also creates mapping challenges when converting historical data. General Equivalence Mappings (GEMs) and other crosswalk tools can help translate older ICD-9 histories into ICD-10-CM, but mappings are not always one-to-one; some ICD-9 concepts split into multiple ICD-10-CM codes or were reorganized elsewhere classified under different headings. As a result, automated crosswalks require clinical review to ensure fidelity. 

Documentation implication: because the code set expanded, coders are instructed to select the most specific code supported by documentation — for bipolar that often means indicating the current episode and any relevant specifier (e.g., with or without psychotic features, in partial remission).

Practical coding details for bipolar presentations — examples and common pitfalls

• Common bipolar codes: F31.0 (current episode hypomanic), F31.1 (current episode manic without psychotic symptoms), and F31.81 (Bipolar II disorder) are frequently used; other F31 subcodes capture depressive episodes, presence of psychotic features, or unspecified presentations. When the longitudinal course is chronic but subthreshold (cyclothymic features), code F34.0 may apply. 
• Example coding scenario 1: A patient presents with a major depressive episode but has clear prior documented hypomanic episodes consistent with Bipolar II. If the current presentation is a nonpsychotic major depressive episode in Bipolar II, the clinician/coder would document Bipolar II and select F31.81 (and, if required by local practice, also indicate the depressive episode detail in clinical notes). 
• Example coding scenario 2 (pitfall): A clinician documents “history of bipolar mood swings” without specifying episode type, psychosis, or remission. That nonspecific language can lead to selection of an unspecified code, which reduces data utility and can affect care coordination and reimbursement. Always document the current episode, course (recurrent vs. single), and any psychotic features to support specific coding.
• Excludes and mapping notes: The ICD-10-CM resource contains guidance such as Excludes2 notes (referred to here as type 2 excludes) that clarify when multiple codes may be used together or when a related condition should be coded separately. Awareness of these guidance notes prevents miscoding when patients have comorbid mood disorders or external causes that change sequencing. 

Clinical modifiers, specifiers, and when multiple codes apply

ICD-10-CM supports using additional codes or modifiers to capture complexity: a clinician may document a bipolar disorder diagnosis plus an additional code for concurrent substance use, a suicide attempt, or a medical comorbidity that affects treatment. The guideline to “code what is documented” means that where documentation supports it, multiple codes (for example, a bipolar code plus a code describing current severity or comorbidity) can be reported to fully reflect clinical status. Specifiers written in the clinical note (e.g., “with mixed features,” “with seasonal pattern,” “in partial remission”) are essential for treatment planning even if not all specifiers map to separate ICD-10-CM categories. 

System-level considerations: surveillance, SMI designation, and behavioral-health programing

Because ICD-10-CM codes are used in registries and claims, they underpin population-level decisions: programs that allocate resources for serious mental illness (SMI) populations commonly rely on diagnostic codes plus functional measures. Accurate bipolar coding therefore affects who gets flagged for care management, intensive case management, or enhanced safety monitoring. In behavioral health quality measurement, the ability to disaggregate subtypes and episode states (depressive vs. hypomanic) improves outcome tracking and service evaluation.

ICD-10-CM Diagnosis Codes for Bipolar Disorder and Diagnostic Criteria

What are the 2026 ICD-10-CM Codes for Bipolar Disorder?

The 2026 ICD-10-CM revision provides a set of precise codes under the F31 category specifically for bipolar disorder. These codes allow clinicians and coders to capture the subtype, current episode, presence of psychotic features, and remission status. The primary codes include:

• F31.0 – Bipolar disorder, current episode hypomanic
• F31.1 – Bipolar disorder, current episode manic without psychotic features
• F31.2 – Bipolar disorder, current episode manic with psychotic features
• F31.3 – Bipolar disorder, current episode depressed, severe, with psychotic features
• F31.4 – Bipolar disorder, current episode depressed, severe, without psychotic features
• F31.5 – Bipolar disorder, current episode depressed, mild or moderate
• F31.6 – Bipolar disorder, current episode mixed
• F31.7 – Bipolar disorder, in remission
• F31.8 – Other specified bipolar disorders, including Bipolar II disorder
• F31.9 – Bipolar disorder, unspecified

Each code corresponds to specific diagnostic criteria and episode characteristics, supporting both clinical care and documentation for billing and coding purposes. Proper code selection requires a thorough assessment of the patient’s mood state, psychotic features, and longitudinal course.

Example: A patient presents with recurrent depressive episodes interspersed with documented hypomanic episodes. The appropriate code would be F31.81 (Bipolar II disorder), capturing both subtype and longitudinal pattern.

How are Bipolar Disorder Codes Structured in ICD-10-CM?

ICD-10-CM codes for bipolar disorder are hierarchical and alphanumeric. The F31 three-character category represents the broad disorder, while the fourth and fifth characters specify:

• Current episode type: manic, hypomanic, depressed, mixed
• Presence or absence of psychotic features
• Remission status: partial or full
• Specific subtypes: Bipolar I, Bipolar II, or cyclothymic disorder (F34.0)

This structure allows a single diagnosis code to capture the clinical nuance of each patient’s condition. For instance, F31.2 (current manic episode with psychotic features) conveys significantly more information than a general “bipolar disorder” label, guiding treatment decisions such as the need for antipsychotic therapy, hospitalization risk, and safety monitoring.

Coding principle: Always code based on documentation of the current episode and longitudinal history, rather than assigning a generic or unspecified code. Using the correct ICD-10-CM code for bipolar disorder ensures accurate tracking of mood swings, recurrence, and severity, which is critical for longitudinal care and insurance billing.

What Specific Codes Should You Be Aware of for Bipolar Disorder?

Clinicians and coders should pay particular attention to:

1. F31.1 – Manic episode without psychotic features: Common for first presentations of bipolar I disorder; the patient is often acutely elevated, disinhibited, or agitated.
2. F31.81 – Bipolar II disorder: Requires hypomanic episodes and major depressive episodes, highlighting the need for detailed patient history to differentiate from unipolar depression.
3. F31.7 – In remission: Use when the patient has a history of episodes but currently exhibits minimal or no symptoms; documentation of remission is essential.
4. F34.0 – Cyclothymic disorder: Chronic mood instability without fully meeting criteria for mania or major depressive episodes; often runs in families.
5. F31.6 – Mixed episodes: Manifests as depressive and hypomanic or manic symptoms simultaneously; requires careful assessment to avoid misdiagnosis.

Clinical example: A 34-year-old patient presents with a 3-week period of elevated mood, decreased need for sleep, and irritability, with prior depressive episodes over the past five years. Coding F31.1 for the current manic episode and noting previous major depressive episodes ensures proper subtype classification and guides pharmacologic interventions such as mood stabilizers.

How to Use ICD-10 Codes for Effective Diagnosis and Treatment?

Effective use of ICD-10 codes for bipolar disorder goes beyond documentation—it informs clinical decisions and treatment planning. Key considerations include:

1. Align code with clinical assessment: Evaluate current episode, psychotic features, and remission status to select the most specific code.
2. Support longitudinal tracking: Accurate coding allows clinicians to monitor recurrence, rapid cycling, and response to treatment over time.
3. Guide pharmacologic and psychosocial interventions: For example, a code indicating current manic episode with psychotic features (F31.2) signals the need for antipsychotic therapy, whereas F31.81 (Bipolar II disorder) may prioritize mood stabilizers and psychotherapy.
4. Facilitate insurance reimbursement: Codes tied to diagnostic criteria for bipolar disorder are used for coverage decisions; proper coding ensures claims are processed and reduces denials.
5. Document subtypes and specifiers: Use codes to capture subtypes, mixed features, and remission status to optimize care continuity and communicate risk factors clearly to all members of the care team.

Example workflow:

• Initial assessment: Determine if patient meets bipolar disorder diagnosis criteria and identify episode type.
• Review history: Check for recurrent mania or depressive episodes, family history, and previous hospitalizations.
• Select code: Choose the most specific 2026 ICD-10-CM diagnosis code that aligns with episode type, psychotic features, and subtype.
• Treatment planning: Use coding to guide medication selection, psychotherapy referrals, and monitoring for even suicide risk.

By integrating ICD-10-CM coding into both assessment and treatment planning, clinicians enhance care precision, support outcome tracking, and meet administrative and legal documentation standards.

Clinical Implications of Bipolar Disorder Codes and Psychotic Features

How Do Bipolar Disorder Codes Impact Treatment Plans?

ICD-10-CM codes for bipolar disorder directly influence the development and implementation of individualized treatment plans. Precise coding communicates not only the diagnosis but also the current episode, presence of psychotic features, and the course of illness, enabling clinicians to tailor interventions appropriately.

Episode-specific treatment planning:

• Manic episode (F31.1 or F31.2): Patients experiencing a current manic episode often require mood-stabilizing medications, adjunctive antipsychotics, and close monitoring for impulsive or risky behaviors. Early and accurate coding ensures that the care team is aware of the episode type and severity.
• Depressive episode (F31.3–F31.5): Accurate coding highlights the need for major depressive episodes treatment strategies, including psychotherapy, possible pharmacologic augmentation, and suicide risk monitoring.
• Bipolar II disorder (F31.81): Documenting hypomanic episodes and prior depressive episodes helps clinicians avoid inappropriate antidepressant monotherapy, which could precipitate mania.

Example: A 25-year-old patient presents with irritability, decreased need for sleep, and racing thoughts. Accurate coding as F31.1 (current manic episode without psychotic features) prompts immediate initiation of lithium therapy and patient education on safety and symptom management, whereas mislabeling the episode as depression could delay effective treatment.

Furthermore, precise codes guide behavioral health interventions, including psychotherapy, psychoeducation, and family support, aligning treatment with the patient’s specific episode type and risk profile. Codes also facilitate rapid cycling identification, helping clinicians adjust treatment frequency and monitoring schedules.

What Role Do These Codes Play in Insurance Reimbursements?

Bipolar disorder ICD-10-CM codes are essential for insurance billing and reimbursement purposes. Health insurers rely on these codes to validate the medical necessity of services, determine coverage for pharmacologic and psychosocial interventions, and authorize hospital admissions or outpatient therapies.

Clinical documentation and reimbursement:

• Detailed coding ensures that bipolar disorder coding aligns with documented diagnostic criteria for bipolar disorder. Incomplete or unspecified coding can lead to claim denials or delayed coverage for necessary treatment.
• Codes such as F31.2 (manic episode with psychotic features) or F31.7 (in remission) signal to payers the severity and complexity of the condition, which can justify higher-intensity interventions or longer hospitalization if clinically indicated.

Example: A patient admitted to an inpatient psychiatric unit with a severe manic episode is coded F31.2. The insurer uses this specific code to authorize hospital services, ensure reimbursement for used for reimbursement purposes, and support continuity of care with outpatient follow-up. Without precise coding, the hospital may face claim denials or retroactive audits.

In addition, proper coding facilitates tracking of service utilization, quality measures, and outcomes in behavioral health programs. Aggregated data on coded episodes help healthcare systems allocate resources efficiently, develop population-level interventions, and optimize care delivery.

How Can Accurate Coding Improve Patient Outcomes?

Accurate ICD-10-CM coding for bipolar disorder enhances patient outcomes through multiple mechanisms:

1. Enhanced clinical decision-making: Proper coding communicates critical information about the current episode, presence of psychotic features, and remission status. This allows clinicians to implement evidence-based pharmacologic and psychosocial interventions promptly.
2. Continuity of care: Standardized codes allow multidisciplinary teams — including psychiatrists, primary care providers, and case managers — to access the same bipolar disorder diagnosis information. This improves coordination, reduces the risk of medication errors, and supports consistent monitoring of symptoms.
3. Risk management: Accurate coding helps identify patients at higher risk for suicide, rapid cycling, or hospitalization. For instance, a patient coded F31.6 (mixed episode) can be prioritized for intensive monitoring and crisis intervention, potentially preventing severe adverse outcomes.
4. Data-driven quality improvement: Aggregated ICD-10-CM data enable healthcare organizations to measure treatment effectiveness, track recovery trajectories, and refine clinical protocols. By monitoring coded episodes over time, clinicians can adjust treatment plans, optimize behavioral health interventions, and implement preventive measures.

Example: A community mental health center reviewing coded data identifies that patients with F31.81 (Bipolar II disorder) have higher rates of recurrent depressive episodes. Using this insight, clinicians develop structured monitoring and early intervention programs, improving overall patient outcomes and reducing hospitalization rates.

Challenges in Diagnosing Recurrent Bipolar Disorder

What Are the Common Misdiagnoses for Bipolar Disorder?

Diagnosing bipolar disorder can be complex due to the disorder’s heterogeneous presentation, fluctuating mood swings, and overlapping symptoms with other psychiatric or medical conditions. Common misdiagnoses include:

1. Major depressive disorder (unipolar depression): Bipolar disorder often first presents with depressive episodes, which can be misinterpreted as major depressive episodes. Without a detailed history of hypomanic episodes, clinicians may fail to recognize the bipolar nature, leading to inappropriate treatment. Example: A 28-year-old patient with recurrent depressive episodes is treated exclusively with antidepressants. Without assessing past manic or hypomanic episodes, the patient may later experience a switch to mania or rapid cycling, complicating clinical management.
2. Attention-deficit/hyperactivity disorder (ADHD): Symptoms such as distractibility, impulsivity, and hyperactivity can mimic mania, particularly in adolescents. Mislabeling these behaviors may result in the use of stimulants that exacerbate mood instability.
3. Personality disorders: Certain traits associated with borderline or histrionic personality disorders, such as affective lability, can be confused with depressive and hypomanic fluctuations in bipolar disorder. Careful longitudinal assessment is critical.
4. Substance-induced mood disorder: Psychoactive substances can produce abnormal mood changes that resemble bipolar episodes. Failure to consider substance use history can lead to misdiagnosis.
5. Medical conditions: Endocrine disorders (thyroid dysfunction), neurological conditions, and sleep disorders can mimic bipolar mania or hypomanic episodes. Comprehensive evaluation is required to rule out physiological contributors.

Clinical impact: Misdiagnoses delay appropriate treatment, increase the risk of adverse outcomes such as even suicide, and may contribute to inappropriate medication exposure. Proper identification of the bipolar subtype and current episode is essential for effective management and coding.

How Can Clinicians Improve Diagnosis Accuracy?

Improving diagnostic accuracy requires a combination of careful history-taking, longitudinal monitoring, and structured assessment:

1. Detailed patient history: Clinicians should document past episodes, mania, hypomanic episodes, major depressive episodes, and family history. A history of bipolar disorder often runs in families; knowledge of genetic predisposition improves recognition.
2. Collateral information: Input from family members, caregivers, or prior treatment providers can reveal mood swings or patterns missed in single-session evaluations.
3. Use of structured diagnostic criteria: Applying standardized criteria from the DSM-5 or diagnostic criteria for bipolar disorder ensures consistent identification of episode type, severity, and duration.
4. Differentiating subtypes: Accurate differentiation between bipolar I disorder and bipolar II disorder is essential. Bipolar II is characterized by hypomanic episodes and recurrent depressive episodes without full mania, while Bipolar I involves at least one manic episode.
5. Awareness of confounding factors: Clinicians must distinguish between substance-induced symptoms, medical comorbidities, and personality disorder traits to prevent misclassification.

Example: A patient presenting with irritability and impulsivity is assessed longitudinally over six months, with collateral reports confirming hypomanic symptoms. Using structured criteria and multiple data sources prevents mislabeling as ADHD or borderline personality disorder, ensuring correct bipolar disorder diagnosis and appropriate ICD-10 coding.

What Tools and Assessments Are Available for Proper Diagnosis?

Several evidence-based tools assist clinicians in the structured evaluation of bipolar disorder:

1. Mood Disorder Questionnaires (MDQ): A self-report instrument that screens for lifetime hypomanic symptoms, mania, and depressive episodes. High sensitivity aids in identifying patients who may require detailed clinical assessment.
2. Structured Clinical Interview for DSM Disorders (SCID-5): A clinician-administered interview that applies diagnostic criteria for bipolar disorder, differentiates between subtypes, and assesses psychotic features when present.
3. Young Mania Rating Scale (YMRS): Evaluates mania severity and tracks response to treatment during acute episodes.
4. Hamilton Depression Rating Scale (HDRS) and Montgomery–Åsberg Depression Rating Scale (MADRS): Assess severity of depressive episodes, helping clinicians identify major depressive episodes in patients with suspected bipolar disorder.
5. Longitudinal tracking and mood diaries: Patients monitor mood swings, sleep patterns, and activity levels. Documentation of depressive and hypomanic episodes over time supports accurate bipolar disorder diagnosis and coding.
6. Family history and genetic tools: Recognizing that bipolar disorder often runs in families, obtaining family psychiatric history and considering genetic markers (when available) can guide diagnosis, particularly for bipolar II disorder is characterized by hypomania and recurrent depression.

Example: A 32-year-old patient presents with intermittent irritability and low mood. The clinician administers the MDQ and SCID-5, corroborates findings with a spouse’s reports of hypomanic behavior, and reviews prior treatment records. Using this comprehensive approach confirms a diagnosis of Bipolar II, allowing for accurate ICD-10-CM coding (F31.81) and targeted treatment planning.

Future of Bipolar Disorder Classification Billing and Coding

How Might ICD Codes Evolve Beyond 2026?

The evolution of diagnostic systems like ICD‑10‑CM suggests that future revisions (such as ICD‑11 and beyond) will increasingly integrate dimensional, biologically‑informed, and digital approaches. For instance, recent literature highlights how ICD‑11 reorganises mood disorders by emphasizing episodes (hypomanic, manic, mixed, depressed) and patterns of illness rather than solely discrete categorical diagnoses. 

Key anticipated changes include:

• Greater emphasis on brain structure and function and genetic‑risk data in defining subtypes of bipolar disorder, to improve the validity of diagnostic categories. 
• Adoption of biomarkers and digital phenotyping (activity/sleep sensors, mobile data) to capture mood‑state fluctuations and potentially support early detection of manic/hypomanic episodes. 
• Refinement of classification for mixed and sub‑threshold presentations (e.g., those historically coded as “unspecified” or “other”), enabling more granular codes and reducing reliance on catch‑all categories. For example, ICD‑11 opens possibilities for more nuanced coding of subtypes. 
• Enhanced global harmonisation and crosswalks between coding systems (ICD, national modifications) to facilitate longitudinal research and global data sharing — allowing for multiple codes, severity specifiers, and adding codes for early‑onset or prodromal states.

Example: In a future update beyond 2026, a patient might be coded not only by “Bipolar I disorder, current manic episode, with psychotic features” but also by a sub‑code that indicates “elevated polygenic risk score & digital mood‑sensor signature” — thereby integrating biological and behavioural data into the classification.

What Trends Are Emerging in Bipolar Disorder Research Subtypes?

Several research trends are influencing how bipolar disorder classification may evolve:

1. Genomics and polygenic risk modelling: Large‑scale genome‑wide association studies (GWAS) are uncovering hundreds of loci associated with bipolar disorder and overlapping with other psychiatric conditions (e.g., schizophrenia).  These findings indicate that the current diagnostic subtypes may be genetically heterogeneous and suggest future classifications might incorporate genetic strata.
2. Neurobiological and digital phenotyping: Studies show that mood disorders involve circuit‑level disruptions (voltage‑gated calcium channels, mitochondria, circadian rhythm genes) and persistent mood instability rather than simply discrete episodes of mania and depression.  Digital sensor data (wrist‑worn actigraphy) are being trialled to detect transitions into hypomanic or manic states. 
3. Refinement of diagnostic validity and prevalence: Comparative reviews show how ICD‑11’s modifications lead to changes in estimated prevalence of bipolar subtypes and highlight issues of diagnostic delay and validity. For instance, use of ICD‑11 criteria may reduce some over‑diagnosis but also risk under‑recognition of early cases. 
4. Focus on repair of residual illness and early intervention: Research on psychoeducation, relapse prevention and sub‑syndromal states (such as sub‑threshold hypomania) is gaining traction. 

These trends together underscore that future classification will likely become more precision‑oriented, combining clinical, genetic, neurobiological and digital data streams.

How Can Patients and Clinicians Advocate for Better Classification in Depressive Episode?

Advocacy by patients and clinicians plays a crucial role in improving classification standards and thereby enhancing care quality.

• Clinician advocacy: Healthcare professionals can contribute to revision boards, provide real‑world data on diagnostic utility, and highlight the limitations of current codes (e.g., “unspecified” entries, lack of subtype specificity). By documenting nuanced clinical presentations (mixed features, rapid cycling, sub‑threshold hypomania) and sharing data, clinicians help to refine future versions of coding systems.
• Patient and peer support networks: Patients and advocacy organizations can document lived‑experience data, participate in research, and push for codes that reflect the full spectrum of bipolar presentations (including early onset, mixed states, and comorbidities). For example, organisations like Depression and Bipolar Support Alliance share outcome data and support efforts to raise awareness of coding’s impact on treatment access. 
• Promoting education and documentation best‑practice: Clinicians should ensure complete documentation (episode type, severity, comorbidities, family history) so that coding systems are fed with high‑quality data. Patients should be encouraged to engage with their records and understand how their diagnosis codes impact care pathways and access to treatments.
• Data sharing and research participation: Both patients and clinicians can support registries, digital phenotype studies, and biomarker research which drives classification reform. Increased participation helps link real‑life clinical data with research findings, facilitating more robust coding structures.

Example: A clinician‑led initiative in a community behavioural‑health centre tracks outcomes of patients coded under “unspecified bipolar disorder” and reports higher relapse rates, prompting local advocacy to refine codes and obtain better mapping for mixed‑episode presentations. Simultaneously, patients attend peer‑led advocacy sessions and share their experiences of mis‑coding, pushing for more specific categories that capture their symptom trajectories.

Conclusion

Bipolar disorder is a complex and heterogeneous mood disorder, marked by fluctuating mania, hypomanic episodes, and major depressive episodes that can significantly impact a person’s functioning, relationships, and quality of life. Accurate identification and classification of bipolar disorder are essential for effective clinical care, appropriate bipolar disorder diagnosis, and targeted treatment planning. The 2026 ICD-10-CM codes (F31 series) provide clinicians with precise tools to document current episodes, psychotic features, remission, and subtypes such as Bipolar I and Bipolar II disorders, supporting both clinical decision-making and insurance billing.

Throughout this article, we highlighted how the ICD-10-CM framework enhances diagnostic specificity, guides evidence-based interventions, and informs risk management strategies. Accurate coding enables clinicians to tailor treatments to individual presentations, monitor mood swings and rapid cycling, and optimize long-term outcomes. Moreover, detailed documentation aids behavioral health programs and ensures proper reimbursement purposes, reinforcing the critical interplay between clinical care and administrative processes.

Despite advances in classification, challenges remain. Misdiagnoses, overlapping symptomatology, and episodic presentations require clinicians to apply structured diagnostic criteria for bipolar disorder, utilize validated tools such as the Mood Disorder Questionnaire and SCID-5, and gather longitudinal and collateral data. Emerging trends in research, including genetic studies, brain structure and function analyses, and digital phenotyping, are poised to refine our understanding of bipolar disorder further and may shape future ICD revisions beyond 2026.

Patients, clinicians, and advocacy groups play an integral role in advancing classification systems. By contributing real-world data, participating in research, and ensuring precise documentation, stakeholders help drive improvements in both diagnosis and care. Staying informed about updates to ICD coding, emerging research, and evolving treatment paradigms is crucial for maintaining high standards in bipolar disorder coding and patient care.

Ultimately, the integration of accurate ICD-10-CM coding with comprehensive clinical assessment fosters a holistic approach to managing bipolar disorder. It ensures that patients receive individualized, evidence-based care, promotes better outcomes, and supports the broader healthcare system in delivering high-quality, accountable, and responsive behavioral health services. Understanding and utilizing these codes is not merely an administrative task — it is a critical component of effective, compassionate, and informed psychiatric practice.

Frequently Asked Questions

What is the ICD-10 code for bipolar disorder?

The primary ICD-10-CM code for bipolar disorder is F31, which is used as the base code for all bipolar subtypes. Specific subtypes and episodes are coded with extensions (e.g., F31.0, F31.1, F31.81).

What is F31.9 bipolar disorder?

F31.9 is the ICD-10-CM code for Bipolar disorder, unspecified. It is used when the clinician recognizes a bipolar disorder but cannot specify the subtype or current episode.

What is the ICD-10 code for F31.30?

F31.30 is the code for Bipolar disorder, current episode depressed, unspecified. It indicates a depressive episode without further specification regarding severity or psychotic features.

What causes bipolar?

Bipolar disorder is caused by a combination of genetic, neurobiological, and environmental factors. It often runs in families, and abnormalities in brain structure and function, neurotransmitter imbalances, and stressful life events can contribute to its development.