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F31.81 ICD-10-CM Code: Bipolar II disorder

F31.81 maps to CMS-HCC V28 154. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC Buddy coding tools

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Code lookupF31.81

FY 2026 Apr update / Mental, Behavioral and Neurodevelopmental disorders (F01-F99) / Mood [affective] disorders (F30-F39)

F31.81

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Bipolar II disorder

A specific type of bipolar disorder characterized by depressive episodes and hypomanic episodes (less severe elevated mood), but without full manic episodes.

Buddy the Bee presenting code insight

Buddy Insight

Bipolar II disorder is characterized by recurrent major depressive episodes alternating with hypomanic (not full manic) episodes.

OverviewRisk ModelsCode BookDocumentationAuditNotesEdition comparison

CMS-HCC V28

HCC 154

Code-level coefficient reference

CMS-HCC V24

Historical

Historical

Not used for CY2026 payment

ACA/HHS

N/A

—

Not mapped

ESRD/PACE

N/A

—

Not mapped

RXHCC

HCC 131

Code-level coefficient reference

Code Book Path

Official
F31Bipolar disorderF31.8Other bipolar disordersF31.81Bipolar II disorder

Inclusion Terms

Official
  • Bipolar disorder, type 2

Excludes 2

Official
  • symptoms, signs and abnormal clinical laboratory findings, not elsewhere classified (R00-R99)Inherited from F01-F99, F31
  • cyclothymia (F34.0)Inherited from F01-F99, F31

Related Codes

Official
F31.89Other bipolar disorder

Includes

Official
  • disorders of psychological developmentInherited from F01-F99, F31
  • bipolar I disorderInherited from F01-F99, F31
  • bipolar type I disorderInherited from F01-F99, F31
  • manic-depressive illnessInherited from F01-F99, F31
  • manic-depressive psychosisInherited from F01-F99, F31
  • manic-depressive reactionInherited from F01-F99, F31
  • seasonal bipolar disorderInherited from F01-F99, F31

Excludes 1

Official
  • bipolar disorder, single manic episode (F30.-)Inherited from F31
  • major depressive disorder, single episode (F32.-)Inherited from F31
  • major depressive disorder, recurrent (F33.-)Inherited from F31

Code First

Official

No Code First sequencing instructions are included in this display for F31.81. Check the code and parent instructions in the Code Book.

Use Additional

Official

No Use Additional Code instructions are included in this display for F31.81. Check the code and parent instructions in the Code Book.

Code Also

Official

No Code Also instructions are included in this display for F31.81. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance
Provider explicitly documents bipolar II disorder (not simply 'bipolar disorder')
History of at least one hypomanic episode documented
History of at least one major depressive episode documented
Absence of full manic episodes in the patient's history

MEAT Support

HCC Buddy guidance
Provider explicitly documents bipolar II disorder (not simply 'bipolar disorder')
History of at least one hypomanic episode documented
History of at least one major depressive episode documented
Absence of full manic episodes in the patient's history

Audit Caution

HCC Buddy guidance
Coding bipolar II as bipolar I — the distinction requires confirming no full manic episodes have ever occurred
Using recurrent major depressive disorder codes (F33.x) when hypomanic episodes are documented in the history
Defaulting to F31.9 (unspecified) when the provider has clearly documented bipolar II
Not recognizing that bipolar II is a specific code (F31.81) rather than part of the severity spectrum

Common Mistakes

HCC Buddy guidance
F31.0 — Bipolar disorder, current episode hypomanic: Bipolar I with current hypomanic episode, not bipolar II
F31.9 — Bipolar disorder, unspecified: Less specific, does not differentiate type I from type II
F33.x — Major depressive disorder, recurrent: No hypomanic episode history
F34.0 — Cyclothymic disorder: Subsyndromal mood fluctuations not meeting bipolar II criteria

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is F31.81 an HCC code?

Yes. F31.81 (Bipolar II disorder) maps to HCC 154, Bipolar Disorders without Psychosis under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.351. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: F31.81 is billable and maps to V28 HCC 154, Bipolar Disorders without Psychosis. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code
F31.81
Description
Bipolar II disorder
HCC (V28)
HCC 154 — Bipolar Disorders without Psychosis
RAF reference coefficient
0.351
Billable
Yes
Payment year
2026

HCC Category Mapping

V28HCC 154, Bipolar Disorders without Psychosis
0.351
RxHCCHCC 131, Bipolar Disorders
Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work F31.81 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for F31.81

For F31.81, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

  • MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
  • EEvaluate: test results, medication response, or physical findings reviewed by the provider
  • AAssess: explicit mention in the assessment or plan with acknowledgment of status
  • TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Coder workflow notes

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What This Code Means

F31.81 is the ICD-10-CM diagnosis code for bipolar ii disorder. A specific type of bipolar disorder characterized by depressive episodes and hypomanic episodes (less severe elevated mood), but without full manic episodes. F31.81 sits in the ICD-10-CM chapter for mental, behavioral and neurodevelopmental disorders (f01-f99), within the section covering mood [affective] disorders (f30-f39).

Under the CMS-HCC V28 risk adjustment model, F31.81 maps to Bipolar Disorders without Psychosis (HCC 154) with a source-labeled community, non-dual, aged reference coefficient of 0.351. No V24 mapping is shown for F31.81; use the applicable model and payment year when reviewing the V28 mapping. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

Bipolar II is distinct from Bipolar I; ensure documentation clearly indicates hypomanic rather than manic episodes. For F31.81, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for F31.81 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •Bipolar II is distinct from Bipolar I; ensure documentation clearly indicates hypomanic rather than manic episodes
  • •Verify that patient has never experienced a full manic episode to confirm Bipolar II diagnosis

Clinical Significance

Bipolar II disorder is characterized by recurrent major depressive episodes alternating with hypomanic (not full manic) episodes. This is a distinct diagnostic entity from bipolar I disorder and carries significant clinical importance due to the predominance of depressive episodes, which account for the majority of illness burden. Bipolar II patients spend more time in depressive states and have high rates of suicidality and functional impairment.

Documentation Requirements

  • ✓Provider explicitly documents bipolar II disorder (not simply 'bipolar disorder')
  • ✓History of at least one hypomanic episode documented
  • ✓History of at least one major depressive episode documented
  • ✓Absence of full manic episodes in the patient's history
  • ✓Current mood state and treatment plan
  • ✓Current medications including mood stabilizers and/or atypical antipsychotics

Commonly Confused Codes

  • •F31.0: Bipolar disorder, current episode hypomanic: Bipolar I with current hypomanic episode, not bipolar II
  • •F31.9: Bipolar disorder, unspecified: Less specific, does not differentiate type I from type II
  • •F33.x: Major depressive disorder, recurrent: No hypomanic episode history
  • •F34.0: Cyclothymic disorder: Subsyndromal mood fluctuations not meeting bipolar II criteria

Child Codes

F31.81Bipolar II disorder
HCC 154
F31.89Other bipolar disorder
HCC 154

Code Hierarchy

└F31Bipolar disorder└F31.8Other bipolar disorders└F31.81Bipolar II disorder
└F31.81Bipolar II disorder

For F31.81, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

F31.81 maps to CMS-HCC V28 category 154, Bipolar Disorders without Psychosis. See the ICD-10 to HCC mapping hub for how the V28 crosswalk works. The mapping identifies a payment HCC category for F31.81. Review its source-labeled HCC coefficient above, check the RAF Calculator with complete member context for CMS-HCC V28 PY2026, and confirm the documentation the chart needs before the code is submitted. HCC Buddy shows no RAF score unless every required source and calculation check passes.

More on F31.81

Referenced in blog posts

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