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Your guide to ICD-10 F codes

Learn more about how to use ICD-10 F codes for mental, behavioral, and neurodevelopmental disorders.

April 18, 2025 • Updated on October 16, 2026

By Ashley Abramson • Clinically reviewed by the Headway Clinical Team

8 min read

By Ashley Abramson • Clinically reviewed by the Headway Clinical Team

Billing for mental health services can be complicated, especially if you work with insurance companies. Let’s say you just finished a 60-minute talk therapy session for a client with major depressive disorder. Along with the CPT code to represent the type of service you provided, you’ll need to include an ICD-10 code that aligns with your client’s diagnosis. 

Using the right code the first time you bill a payer is a key component of compliance — and making sure you get paid for your work in a timely manner. Below, learn more about how to use ICD-10 F codes for mental, behavioral, and neurodevelopmental disorders.

Whart to know

1

ICD-10 F codes classify mental, behavioral, and neurodevelopmental disorders commonly diagnosed by mental health providers, from ADHD to substance use disorders.

2

ICD-10 F codes are organized by “family” (i.e., mood disorders), with more specific diagnoses nested within each family (i.e., major depression). Aim to choose the most specific defensible code.

3

ICD-10 and CPT codes go hand-in-hand, but they’re different. ICD-10 codes detail why you’re billing a payer (i.e., your client’s diagnosis), while CPT codes describe the services for which you’re billing.

4

Headway offers comprehensive billing and claims support, so you can spend less time deciphering ICD-10 codes and more time caring for your clients.

A simple breakdown of ICD-10 F codes

The ICD-10 is the International Classification of Diseases, 10th Revision, used by medical providers in medical records, billing, and treatment plannings. Specifically, ICD-10 F codes classify mental, behavioral, and neurodevelopmental disorders commonly diagnosed by mental health providers. Accurate coding helps ensure proper diagnosis and treatment and insurance reimbursement.

Annual ICD-10 code updates

ICD-10 codes are updated each year on the first day of October. Some codes may be removed altogether, while others are updated or added. You can refer to ICD-10 Diagnosis Code Changes for recent updates to ICD-10 coding conventions that may impact you as a therapist. 

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The full list of ICD-10 F codes by disorder category

ICD-10 F codes encompass mental, behavioral, and neurodevelopmental disorders. These codes are organized into specific diagnostic groupings that help clinicians and coders accurately classify a wide range of psychiatric and psychological conditions.

The main categories and their code ranges are as follows:

Code rangeCategoryWhat it covers
F01–F09Mental disorders due to known physiological conditionsCognitive and psychiatric symptoms caused by an underlying medical condition
F10–F19Mental and behavioral disorders due to psychoactive substance useUse, abuse, and dependence across alcohol and each drug class
F20–F29Schizophrenia, schizotypal, delusional, and other non-mood psychotic disordersSchizophrenia spectrum, delusional, and schizoaffective diagnoses
F30–F39Mood (affective) disordersDepressive, bipolar, and persistent mood diagnoses, with severity and episode in the code
F40–F48Anxiety, dissociative, stress-related, somatoform and other nonpsychotic mental disordersThe largest block for outpatient therapy — anxiety, OCD, PTSD, adjustment, dissociative, and grief diagnoses
F50–F59Behavioral syndromes associated with physiological disturbances and physical factorsEating, sleep, and sexual dysfunction diagnoses not caused by a substance or medical condition
F60–F69Disorders of adult personality and behaviorPersonality disorders, impulse-control disorders, and gender dysphoria
F70–F79Intellectual disabilitiesSeverity-graded intellectual disability diagnoses
F80–F89Pervasive and specific developmental disordersAutism spectrum, speech and language, and learning disorders
F90–F98Behavioral and emotional disorders with childhood or adolescent onsetADHD, conduct, separation anxiety, and tic disorders — usable at any patient age
F99Unspecified mental disorderA single catch-all code for when no more specific diagnosis can be established

The most frequently used ICD-10 F codes

Some ICD-10 F codes are used more frequently by therapists than others. The most common ICD-10 F codes at Headway include:

F41.1: Generalized Anxiety Disorder

Use this code for clients experiencing excessive and persistent worry and anxiety for at least six months. Along with difficult-to-control worry, symptoms of generalized anxiety disorder may include restlessness, difficulty concentration, irritability, muscle tension, and sleep problems.

F33.1: Major Depressive Disorder, Recurrent, Moderate

This code applies when a client has had at least one prior depressive episode and is currently experiencing moderate symptoms, including low mood, diminished interest in normal activities, and sleep and appetite changes.

It differs from mild or severe episodes based on symptom intensity. Whereas severe episodes interfere drastically with someone’s daily activities, mild episodes present with symptoms but do not significantly impair functioning.

F43.23: Adjustment Disorder With Mixed Anxiety and Depressed Mood

Use this code for clients struggling with a recent identifiable stressor, such as job loss or divorce, who exhibit both anxiety and depression symptoms that are out of proportion to the stressor but do not meet criteria for GAD or major depressive disorder. Adjustment disorder with only anxiety or depression can also be used.

F41.9: Anxiety Disorder, Unspecified

This is a general code that represents anxiety symptoms that don’t fit neatly into a specific anxiety disorder, such as GAD, panic disorder, OCD, or phobias. It can be useful when a client’s symptoms are unclear or evolving over time.

F43.12: Post-Traumatic Stress Disorder, Chronic

Use this code for clients who have experienced trauma and continue to struggle with symptoms such as intrusive thoughts, avoidance, and hyperarousal for more than three months. Chronic PTSD suggests prolonged stress beyond the acute phase.

F32.9: Major Depressive Disorder, Single Episode, Unspecified

This code is used when a client presents with depressive symptoms that seem like major depressive disorder, but the severity, recurrence status, or specific features aren’t clearly defined.

F90.2: ADHD, Combined Type

This code is used for clients whose attention-deficit/hyperactivity disorder is classified as “combined type,” meaning it includes features of both inattentiveness and hyperactivity. As the most commonly diagnosed form of ADHD, this is a code you’ll likely use often.

How are F codes related to other codes?

ICD-10 vs. CPT codes: What’s the difference?

ICD-10 and CPT codes go hand in hand for compliant billing. While ICD-10 codes indicate your client’s diagnosis, or why you’re billing the payer, CPT codes convey the service for which you’re billing.

For example, you’d use an ICD-10 code to communicate you’re treating a client with generalized anxiety disorder. A CPT code would represent the treatment for that client’s condition, such as a 60-minute psychotherapy session.

F codes vs. Z codes: which one do you bill?

ICD-10 F codes are used for mental, behavioral, and neurodevelopmental disorders diagnosed by mental health providers.

ICD-10 Z codes, by contrast, add context about specific circumstances that caused someone to seek mental health care, beyond their official diagnosis. For example, you might use a Z code if a patient’s condition was shaped by housing issues, a problem at work, or a specific family crisis. An ICD-10 Z code may also be appropriate if a client needs support while dealing with a particular stressor, but doesn’t meet criteria for a specific diagnosis.

By definition, Z codes refer to problems outside of a specific injury or illness. That means you generally cannot bill insurance using a Z code alone, because it’s not enough to establish medical necessity. You will typically have to pair a Z code with another ICD-10 code, such as an F code, if you’re seeking insurance reimbursement.

Are F codes the same as DSM-5 codes?

Yes, the diagnostic codes printed in the DSM-5-TR are ICD-10-CM codes.

The DSM-5-TR, published by the American Psychiatric Association, is a manual that details diagnostic criteria for mental health conditions. The ICD-10-CM, meanwhile, is the coding system derived from the World Health Organization’s ICD-10 framework that’s used in the United States. Although the two systems were developed by different organizations, they are meant to work together.

How to choose the most specific F code

There’s a time and a place for unspecified codes. For example, they can be useful early in your relationship with a new client, when you’ve determined their broad diagnosis but are still trying to understand their specific presentation.

An unspecified code should not be used as a permanent substitute for a more granular code, though. In fact, using an unspecified code may be grounds for a claim denial, just like using the wrong code entirely. To make sure you’re selecting the right code every time, use this general process.

  1. Determine the correct ICD-10 F code family: Rule out other medical conditions, mental health diagnoses, or substance use that could explain symptoms
  2. Assess specifiers: Duration and severity of symptoms are two of the most common specifiers to watch for
  3. Verify diagnostic and coding requirements: Make sure your client meets all DSM-5-TR criteria for your chosen diagnosis, then double check you’ve selected the corresponding ICD-10 F code
  4. Document your decision-making: Note everything that went into your decision, including criteria met, diagnoses ruled out (and why), and relevant specifiers assessed

Common F code mistakes that trigger denials

You can’t avoid mistakes if you don’t know they’re mistakes. Watch out for these common F code mishaps to avoid denials, delays, and audits.

  • Choosing the wrong ICD-10 F code: Assess diagnostic criteria carefully, rule out differential diagnoses, and double check that your diagnosis and ICD-10 F code match.
  • Not getting specific enough: Choosing a general ICD-10 F code may seem like the safest route—but it can backfire. Always choose the most specific defensible code and back it up with thorough documentation.
  • Using an ICD-10 Z code without an F code: Remember, you usually can’t bill insurance with a Z code alone. Make sure to pair ICD-10 F and Z codes where relevant.

FAQs about F codes

Are all F codes mental health diagnoses?

No. While many F codes are mental health diagnoses, this chapter also includes developmental disorders and intellectual disabilities.

What is the F code for no diagnosis?

There is no F code for “no diagnosis,” as these codes are used for diagnosable mental health, behavioral, and neurodevelopmental disorders. An ICD-10 Z code may be more appropriate if your client does not meet criteria for an F code—but remember that you generally can’t bill insurance using a Z code alone.

How often do F codes change?

ICD-10 codes are updated annually, with changes effective each year on October 1.

Get more coding and billing help with Headway

Compliant coding and billing are essential parts of a successful practice, but they can be stressful and time-consuming. Headway makes getting paid a breeze by taking the administrative load of coding and billing off of mental health providers. Instead of spending time looking up codes and submitting insurance claims, you can focus your energy on helping your clients thrive.

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This content is for general informational and educational purposes only and does not constitute clinical, legal, financial, or professional advice. All decisions should be made at the discretion of the individual or organization, in consultation with qualified clinical, legal, or other appropriate professionals.

© 2026 Therapymatch, Inc. dba Headway. All rights reserved. No part of this publication may be reproduced without permission.

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