What is ICD-10 code F31.78?

F31.78 is the ICD-10-CM diagnosis code for Bipolar disorder, in full remission, most recent episode mixed. It belongs to the ICD-10-CM chapter for mental, behavioral and neurodevelopmental disorders (f01-f99). F31.78 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. F31.78 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. F31.78 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. F31.78 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

What is the V28 vs V24 difference for F31.78?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. F31.78 was a payment HCC under V24 (Major Depressive, Bipolar, and Paranoid Disorders) but the V28 recalibration removed it from the risk adjustment model. Both models can still appear in legacy data and in payer-specific lookback periods.

What should coders know when reporting F31.78?

Use this code only when documentation clearly states the patient is in 'full remission' or 'complete remission' - partial remission requires a different code (F31.77) The 'most recent episode mixed' component is important; verify the last bipolar episode involved both manic and depressive features before assigning this specific code Because F31.78 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

F31.78: Bipolar disorder, in full remission, most recent episode mixed — ICD-10 | Major

ICD-10-CM Code View

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Code lookupF31.78Effective periodFY2026 Apr Update (Apr 1-Sep 30)

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

F31.78

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

Bipolar disorder, in full remission, most recent episode mixed

This code describes bipolar disorder where the patient has completely recovered from their most recent mixed episode (which included both manic and depressive symptoms) and is currently experiencing no symptoms. The condition is in remission, meaning the patient is stable and symptom-free at this time.

Buddy Insight

Bipolar disorder in full remission with the most recent episode being mixed indicates complete resolution of symptoms from the last mixed mood episode.

CMS-HCC V28

Not risk-adjusted for this model/period.

RAF 0

CMS-HCC V24

Mapped

HCC 59

Major Depressive, Bipolar, an...

RAF 0.309

ACA/HHS

Not risk-adjusted for this model/period.

RAF 0

ESRD/PACE

Mapped

HCC 59

Major Depressive, Bipolar, an...

RAF 0.0

RXHCC

Mapped

HCC 131

Bipolar Disorders

RAF 0.0

Code Trumping

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Code Book Path

Official

F31Bipolar disorder

F31.7Bipolar disorder, currently in remission

F31.78Bipolar disorder, in full remission, most recent episode mixed

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for F31.78 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for F31.78 in this effective period.

Related Child Codes

Official

F31.70Bipolar disorder, currently in remission, most recent episode unspecified

F31.71Bipolar disorder, in partial remission, most recent episode hypomanic

F31.72Bipolar disorder, in full remission, most recent episode hypomanic

F31.73Bipolar disorder, in partial remission, most recent episode manic

F31.74Bipolar disorder, in full remission, most recent episode manic

Includes

Official

ICD-10-CM does not list Includes notes for F31.78 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for F31.78 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for F31.78 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for F31.78 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for F31.78 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Confirmed bipolar disorder diagnosis

Most recent episode identified as mixed

Full remission with complete absence of mood symptoms documented

Maintenance medication regimen

MEAT Support

HCC Buddy guidance

Confirmed bipolar disorder diagnosis

Most recent episode identified as mixed

Full remission with complete absence of mood symptoms documented

Maintenance medication regimen

Audit Caution

HCC Buddy guidance

Using full remission when any residual manic or depressive symptoms are present

Not identifying the most recent episode type correctly

Discontinuing bipolar coding during remission visits

Failing to differentiate mixed episode history from rapid cycling

Common Mistakes

HCC Buddy guidance

F31.77 — Bipolar disorder, partial remission, most recent mixed: Residual symptoms present

F31.74 — Bipolar disorder, full remission, most recent manic: Different episode type

F31.76 — Bipolar disorder, full remission, most recent depressed: Different episode type

F31.70 — Bipolar disorder, remission, unspecified: Less specific

Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.

Is F31.78 an HCC code?

Yes. F31.78 maps to Major Depressive, Bipolar, and Paranoid Disorders under the V24 model but is not retained in V28.

HCC Category Mapping

V24HCC 59, Major Depressive, Bipolar, and Paranoid Disorders

0.309

ESRDHCC 59, Major Depressive, Bipolar, and Paranoid Disorders

0.000

RxHCCHCC 131, Bipolar Disorders

0.000

RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.

Work F31.78 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for F31.78

For F31.78to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

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

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed F31.78 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

F31.78 is the ICD-10-CM diagnosis code for bipolar disorder, in full remission, most recent episode mixed. This code describes bipolar disorder where the patient has completely recovered from their most recent mixed episode (which included both manic and depressive symptoms) and is currently experiencing no symptoms. The condition is in remission, meaning the patient is stable and symptom-free at this time. F31.78 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 older CMS-HCC V24 model, F31.78 maps to Major Depressive, Bipolar, and Paranoid Disorders (HCC 59) with a community, non-dual, aged base RAF weight of 0.309. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.

Use this code only when documentation clearly states the patient is in 'full remission' or 'complete remission' - partial remission requires a different code (F31.77). Because F31.78 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. 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, RAF weights, and MEAT documentation criteria for F31.78 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Use this code only when documentation clearly states the patient is in 'full remission' or 'complete remission' - partial remission requires a different code (F31.77)
•The 'most recent episode mixed' component is important; verify the last bipolar episode involved both manic and depressive features before assigning this specific code

Clinical Significance

Bipolar disorder in full remission with the most recent episode being mixed indicates complete resolution of symptoms from the last mixed mood episode. Full remission from a mixed episode is a positive clinical milestone given the complexity and treatment resistance of mixed states. Continued monitoring is warranted due to the high recurrence rate.

Documentation Requirements

✓Confirmed bipolar disorder diagnosis
✓Most recent episode identified as mixed
✓Full remission with complete absence of mood symptoms documented
✓Maintenance medication regimen
✓Relapse monitoring plan

Commonly Confused Codes

•F31.77: Bipolar disorder, partial remission, most recent mixed: Residual symptoms present
•F31.74: Bipolar disorder, full remission, most recent manic: Different episode type
•F31.76: Bipolar disorder, full remission, most recent depressed: Different episode type
•F31.70: Bipolar disorder, remission, unspecified: Less specific