20 Most Commonly Used ICD-10 Codes in Mental Health in 2021

If you’re wondering about trends in mental health over the past year, you’re not the only one. To get more insight into the usage and trends of the behavioral health community in 2021, we identified the most common ICD-10 codes used by SimplePractice customers. 

This data on the most frequently used ICD-10 codes is pulled from SimplePractice customers who have billed insurance over the last calendar year, so this report represents common diagnostic codes used by solo or small group providers in the behavioral health space across the country. 

What Are ICD Codes?

ICD codes, or International Classification of Disease codes, are used to describe a diagnosis when billing insurance. ICD codes are developed by the World Health Organization, and are used across the medical field to describe a huge variety of conditions. Aside from being used to bill for healthcare services, they’re also a way to identify health and disease trends across countries using a standard diagnostic language. 

Top Billed ICD-10 Codes

Here, we’ve compiled a list of the most frequently used ICD-10 codes used for mental health conditions in 2021. 

RankCodeDiagnosis
1F41.1Generalized anxiety disorder
2F43.23Adjustment disorder with mixed anxiety and depressive mood
3F33.1Major depressive disorder, recurrent, moderate
4F43.22Adjustment disorder with anxiety
5F43.20Adjustment disorder, unspecified
6F41.9Anxiety disorder, unspecified
7F43.10Post traumatic stress disorder, unspecified 
8F43.21Adjustment disorder with depressed mood
9F43.12Post traumatic stress disorder, chronic
10Z63.0Problem in relationship with spouse or partner
11F33.0Major depressive disorder, recurrent, mild
12F90.2Attention-deficit hyperactivity disorder, combined type
13F32.1Major depressive disorder, single episode, moderate
14F34.1Dysthymic disorder
15F90.0Attention-deficit disorder, predominantly inattentive type
16F33.2Major depressive disorder, recurrent, without psychotic features
17F32.0Major depressive disorder, single episode, mild 
18F43.25Adjustment disorder with mixed disturbance of emotions and conduct
19F41.0Panic disorder (episodic paroxysmal anxiety)
20F84.0Autistic disorder


The most used ICD-10 code for anxiety was for F41.1—generalized anxiety disorder. This continues trends from the top billed codes in 2019 and even from 2017 as well. 

Top Diagnoses Categories

To get a better understanding of the top diagnoses made in 2021, we took the 20 codes listed above and rolled them up into 4 corresponding categories, as shown below. 

RankCategory% of total diagnoses
1Adjustment disorders20% 
2Major depressive disorders20%
3PTSD8%
4Attention-deficit hyperactivity disorders8%


Changes to ICD Codes in 2022

On January 1, 2022, the ICD-10 updated to the ICD-11, as mandated by the WHO. The ICD-11 reflects advances in science and medicine, and aligns classifications with the latest knowledge of disease prevention and treatment. Some notable changes in the ICD-11 include: 

  • New core chapters for “diseases of the immune system,” “sleep-wake disorders,” and “conditions related to sexual health.” 
  • Overall coding improvements to allow more precise data collection, including new codes for antimicrobial resistance, specific coding for clinical stages of HIV, codes for common skin cancers, and more. 
  • Improved ease of coding requires less user-training, and new availability for online and offline functioning 

To learn more about the updates to ICD-11, you can visit the WHO’s website dedicated to the update, where you’ll find more resources on the changes and how to implement them in your practice. 

When Do You Have to Actually Start Using ICD-11?

There’s often a delay between when ICD updates are published and when they actually start being used, and the ICD-11 is no exception. Although the updates officially became available to member states of the WHO as of January 1, 2022, the US doesn’t have an official implementation plan for rollout, and they may not be implemented until 2025. It’s up to each country to make the shift, and it’ll take some time for the US to update from the ICD-10. 

How the ICD Updates Impact Your Practice

Since the ICD codes are used across multiple healthcare fields, there’ll probably be a lot of codes in each update that don’t apply to your billing. But, you do want to review the annual updates carefully—if you use a deleted code that’s no longer recognized, or try to use an old version of a code, the reimbursement for that service may be denied. 

If you have a list of the previous codes that you use frequently in your practice, you can use the “Search” Function in documents from CMS to only look directly for what you need. That way you can quickly determine what changes, if any, have been made to your most regularly used codes and make the necessary adjustments to your billing documents. 

The world of insurance billing can get complicated pretty quickly. To avoid getting stuck in endless billing conversations, set aside a block of time to go through all the new information thoroughly one time, and get all the relevant information. Then you can be confident that your billing is set up correctly, and spend that time with your clients instead.

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