ICD-10 Codes for Bipolar Disorder: F31.9 and Related Codes

A chart may list bipolar disorder for years. That does not automatically make F31.9 the right code for every visit. F31.9 means bipolar disorder, unspecified. If the current note identifies the episode, severity, psychotic features, remission status, or Bipolar II disorder, a more specific code from the F31 family may be appropriate.

Coding problems begin when the diagnosis is clinically clear to the psychiatrist but too broad in the billing record. In another case, the opposite happens: a coder sees symptoms, medications, or an old diagnosis and fills in details that the current note never actually establishes.

For practices, accurate bipolar coding comes down to keeping those two situations separate. Report what the clinician documented for the encounter, at the level of specificity the record supports.

F31.9 Is Only One Part of the Bipolar Code Family

There are various codes that represent different bipolar disorders. The F31 category covers a range of diagnoses. It includes current hypomanic, manic, depressive, and mixed episodes. Several of those groups divide further according to severity or psychotic features. The category also contains remission codes, F31.81 for Bipolar II disorder, and F31.89 for other bipolar disorder.

That makes F31.9 a narrower answer than “the bipolar code.”

Use of F31.9 makes sense when the provider establishes bipolar disorder but the documentation does not support one of the more specific diagnoses. If the assessment contains enough information to move beyond “unspecified,” the record should be reviewed before defaulting to F31.9.

A few examples make the difference clearer

A psychiatrist might document:

• “Bipolar disorder, unspecified.”
• “Bipolar II disorder.”
• “Bipolar disorder, current episode hypomanic.”
• “Bipolar disorder, current episode manic, moderate, without psychotic features.”
• “Bipolar disorder, current episode depressed, severe with psychotic features.”
• “Bipolar disorder, in full remission, most recent episode manic.”

Those statements describe different clinical situations. They should not all collapse into F31.9.

CMS’s current psychiatry and psychology billing guidance includes the F31 remission codes, F31.81, F31.89, and F31.9 among the applicable diagnosis codes.

The F31 Code List for 2026

For a coding reference, the full F31 family is below.

The current CMS billing article lists the F31.73 through F31.78 remission codes as well as F31.81, F31.89, and F31.9.

Which code set applies right now?

As of September 25, 2026, FY2026 ICD-10-CM is still the code set used for current encounters. CMS issued an April 1, 2026 update that applies through September 30, 2026. The FY2027 ICD-10-CM files become effective on October 1, 2026. 

How to Choose the Right Bipolar Disorder ICD-10 Code 

The clinical documentation provided by the physician and code should always match. A long psychiatric history may include past mania, depression, medication changes, or hospitalizations, but those older records do not determine today’s code. 

If the note only says “bipolar disorder”

Suppose the assessment reads:

Bipolar disorder. Continue current medication.

The note does not identify a current episode or its severity. It also leaves out whether psychotic features are present and whether the patient is in remission.

In that situation, F31.9 may be the appropriate code if no other part of the documentation establishes additional specificity.

Now change the assessment to:

Bipolar disorder, current episode depressed, moderate. Continue medication and psychotherapy.

The clinician has now supplied information that points toward F31.32.

The difference did not come from the patient’s medication list. It came from the diagnosis documented in the encounter.

The current episode matters

When the clinician identifies an episode, look for the terminology used in the assessment.

A patient can be documented as having:

• A hypomanic episode
• A manic episode
• A depressive episode
• A mixed episode

The code family then narrows further in some circumstances.

Historical information can help the clinician understand the patient’s condition, but it should not be used to manufacture a current episode for the claim.

Severity should come from the clinician

Several F31 codes distinguish mild, moderate, and severe presentations.

That does not mean a coder should calculate severity from the number of symptoms in the note. A patient taking multiple psychiatric medications is not automatically “severe,” and a patient who once required hospitalization does not automatically qualify for a severe current episode.

If the clinician documents the severity, the coding process can use it. If the note does not establish it, the coder should not fill the gap independently.

Psychotic features need supporting documentation

The severe manic, depressive, and mixed groups contain separate options for cases with psychotic features. An antipsychotic prescription alone does not establish psychosis. Neither does a psychiatric admission.

Stable does not automatically mean unspecified

This is another area where a problem list can create confusion.

A patient may be stable on treatment while the clinician documents full remission. Another patient may simply have a stable chronic diagnosis without a documented remission status.

Those situations should not be treated as interchangeable.

The F31.7x codes provide separate options for partial and full remission and, where specified, the most recent episode.

Bipolar II has its own code

If the clinician writes Bipolar II disorder, the relevant code is F31.81.

That is worth checking whenever F31.9 appears repeatedly on claims for a patient whose psychiatric notes consistently identify Bipolar II.

What Does Good Documentation Look Like?

The difference between a difficult claim and a clean claim can sometimes be one sentence in the assessment.

Consider this:

Bipolar disorder. Doing well. Continue current medications.

It tells the reader that bipolar disorder remains part of the treatment picture, but it does not establish a current episode or remission status.

Now consider:

Bipolar II disorder. Symptoms remain controlled on the current regimen. No acute depressive symptoms reported today. Continue medication management.

The second note gives the coding process a documented subtype and additional clinical context.

That does not mean clinicians should write notes for the billing department. The purpose of the assessment remains patient care. But when the diagnosis is clearly stated, the coding process has much less room for interpretation.

For bipolar-related encounters, documentation may address:

• The diagnosed bipolar disorder or subtype
• Current episode, when applicable
• Severity, when applicable
• Psychotic features, when applicable
• Remission status
• Relevant changes since the previous visit
• Treatment decisions
• Medication management
• Clinical reasoning supporting the assessment

The FY2026 Official Guidelines emphasize assigning codes based on documentation and reporting the highest degree of specificity supported by the medical record.

The Diagnosis Code Is Only Half of the Claim

A bipolar diagnosis does not tell the payer which psychiatric service took place. That is where CPT coding enters the picture. Depending on the encounter, psychiatric claims may involve diagnostic evaluation, psychotherapy, crisis services, family psychotherapy, group psychotherapy, or psychotherapy performed with an E/M service.

CPT coding depends on the service provided. 90791/90792 cover psychiatric evaluations, while 90832, 90834, and 90837 cover psychotherapy without E/M. Psychotherapy with E/M may use 90833, 90836, or 90838. 90785 may apply when interactive complexity is documented.

Crisis psychotherapy is coded separately with 90839 for the first 60 minutes and 90840 for each additional 30 minutes. These crisis codes have specific billing restrictions and should not be reported with the related psychiatric codes listed by CMS.

So a claim should not be built around the diagnosis alone. The CPT selection needs to match what actually occurred during the encounter and what the documentation supports.

A Few Bipolar Coding Errors Are Particularly Easy to Repeat

The problem-list trap

A diagnosis can remain on a problem list long after the clinical picture changes. If billing staff pull the same diagnosis from the problem list for every encounter, they can miss a more specific diagnosis in the current assessment.

The medication trap

Lithium, mood stabilizers, or antipsychotic medications can be part of bipolar treatment. They do not tell the coder which F31 code to assign. Medication history is not a substitute for the provider’s diagnosis.

The symptom trap

Racing thoughts, reduced sleep, impulsivity, irritability, and depressed mood may all appear in psychiatric documentation. The coding staff should not turn those symptoms into a bipolar diagnosis independently.

The severity trap

“Complex patient” and “severe episode” are not interchangeable terms. If severity affects the selected F31 code, it needs support in the clinical documentation.

The historical-episode trap

A patient who previously experienced mania may later present in remission or with a depressive episode. The old episode should not automatically become today’s diagnosis.

The unspecified-code habit

F31.9 can be correct. The problem comes when it becomes the answer before anyone checks whether the note supports something more specific.

What About Outpatient and Inpatient Coding?

The setting matters when a bipolar diagnosis remains uncertain.

In outpatient coding, terms like probable, suspected, or rule-out do not support coding a condition as confirmed. Instead, code the highest level of certainty documented, such as the patient’s symptoms, signs, abnormal findings, or confirmed diagnosis. 

Inpatient coding has different rules for certain uncertain diagnoses.

That difference matters when a patient is undergoing an initial psychiatric evaluation. A note stating that bipolar disorder is being considered does not automatically justify F31.9 on an outpatient claim.

Can a Lab Test or Screening Tool Establish Bipolar Disorder?

The answer is no but laboratory tests can still be clinically valuable. A psychiatrist may order testing to investigate other possible causes of symptoms, monitor treatment, or assess medication safety.

The same applies to screening questionnaires. A positive screening result can prompt further evaluation, but it does not give billing staff the authority to assign F31.9 without appropriate provider documentation.

The same caution applies to medications. Seeing lithium or another psychiatric medication in the medication list is not enough to determine the patient’s bipolar subtype or current episode.

Does Bipolar Disorder Have a Special Sequencing Rule?

There is no universal instruction that makes F31.9 the first-listed diagnosis on every claim involving bipolar disorder.  The appropriate sequencing truly depends on the circumstances of the encounter, the mentioned conditions, the setting, the ICD-10-CM guidelines, and insurance requirements.

For example, a visit focused on managing a patient’s bipolar disorder may require a different diagnosis sequence than a visit where another condition is the main reason for care and bipolar disorder is also documented. 

Let’s take an example, 

The practice should therefore review the actual reason for the encounter instead of applying a permanent “bipolar first” rule.

Seven Documentation Examples Worth Reviewing

The examples also show why the phrase “bipolar disorder” by itself can be misleading. It may represent a genuinely unspecified diagnosis, or it may simply be a shortened problem-list label while the assessment contains more detail.

A Practical Claim Review for Medical Practices

Instead of waiting for a payer denial, practices can audit a sample of bipolar claims and compare three things:

• What did the clinician diagnose?

• What diagnosis reached the claim?

• What service did the clinician actually provide?

If those three pieces do not line up, the practice has a starting point for investigation.

A useful internal review can look for:

• Frequent use of F31.9 despite specific diagnoses in the notes
• Bipolar II documented clinically but not reflected on claims
• Acute episode codes continuing after remission is documented
• Severity appearing on claims without clear documentation
• Psychotic-feature codes without supporting assessment language
• Psychotherapy CPT codes without adequate time documentation
• Incorrect combinations of psychiatric CPT services
• Diagnosis codes pulled from outdated problem lists
• Claims using the wrong ICD-10-CM update for the date of service
• Recurring payer denials involving diagnosis or documentation

For an Oregon medical practice, this type of review can also separate a genuine coding problem from other revenue-cycle issues such as payer edits, authorization requirements, eligibility problems, or claim follow-up.

Frequently Asked Question

What is the Bipolar Disorder ICD-10 Code?

F31.9 is the ICD-10-CM code for bipolar disorder, unspecified. It is not the only bipolar diagnosis code. The F31 category includes codes for specific episodes, severity levels, psychotic features, remission, Bipolar II disorder, and other bipolar disorders.

Is F31.9 a billable code?

Yes. F31.9 is a specific ICD-10-CM code for bipolar disorder, unspecified. Whether it is the correct code for a particular claim depends on what the clinician documented.

What is F31.81 used for?

F31.81 is used for Bipolar II disorder. When the provider documents Bipolar II, the practice should review that code rather than automatically using F31.9.

When is F31.9 appropriate?

F31.9 is appropriate when bipolar disorder is established but the documentation does not provide enough information to assign a more specific F31 diagnosis.

Can a coder assign F31.9 from a patient’s medication list?

No. Medication history can provide clinical context, but it does not replace provider documentation of the diagnosis.

Which CPT codes may appear with a bipolar diagnosis?

Depending on the service, claims may include psychiatric evaluation, psychotherapy, interactive-complexity, family, group, or crisis codes. Common examples include 90791, 90792, 90785, 90832, 90833, 90834, 90836, 90837, 90838, 90839, 90840, 90846, 90847, and 90853. The correct code depends on the service and documentation.

Does every bipolar patient receive F31.9?

No. F31.9 is the unspecified option. A more specific F31 code may apply when the documentation supports one.

Can bipolar disorder be coded while the patient is in remission?

Yes. The F31.7x group includes codes for documented partial and full remission, with additional detail about the most recent episode.

Conclusion

F31.9 has a specific place in bipolar disorder coding, but it should not become a default code simply because “bipolar disorder” appears somewhere in the chart. The current assessment may support a much more specific diagnosis.

For cleaner claims, practices should connect the provider’s assessment, the selected F31 code, and the CPT service before submission and verify the ICD-10-CM version that applies to the date of service.