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Top ICD 10 Codes for Occupational Therapy

Because there are many different occupational therapy ICD-10 codes, some of which are quite similar, it can be challenging to know which to use when assessing and treating patients. This post will explore the common mistakes to avoid when assigning ICD-10 codes and tips for selecting the most accurate code for billing purposes. We’ll close with a list of common ICD-10 codes that occupational therapists use most frequently.

What is ICD-10 Coding?

ICD-10 is the 10th revision of the International Statistical Classification of Diseases and Related Health Problems. This framework is the World Health Organization’s medical and therapeutic classification system. It’s a standardized system that allows medical and therapy professionals to code a wide variety of diseases, external causes of injury, treatment of conditions, and more.


The United States was the last country with a modernized health care system to adopt ICD-10 coding standards. On October 1, 2015, the U.S. officially moved away from ICD-9, the older code set that had been in use since 1979. The use of ICD-10 is now mandatory for all entities covered under HIPAA.

ICD-10 codes are a combination of three to seven alphanumeric characters. There are two types of ICD-10 codes: medical diagnosis codes and treatment diagnosis codes. The patient’s physician assigns medical diagnosis codes. A therapist can assign treatment diagnosis codes. ICD-10 codes don’t replace CPT codes — it’s important to note that you much include them both on billing claim forms.

Common ICD-10 Coding Mistakes

The move to ICD-10 was a double-edged sword for occupational therapists. The new code set contains over five-and-a-half times more codes than its predecessor. More specific codes allow you to select the code that accurately and clearly describes a patient’s current deficit area. But with more similar-but-slightly-different codes available, the chances of incorrectly coding a treatment diagnosis have increased. Here are some of the most common ICD-10 coding mistakes and how to avoid them.

1. Using Outdated Codes

ICD-9 was replaced in 2015. Although it’s been several years, if you were familiar with the old way of coding, it may be easy to inadvertently revert to outdated codes, especially if you’re rushing or tired. If you use an old code, your chances of an insurer rejecting your billing claim are all but assured.

2. Confusing Similar Letters and Numbers

ICD-10 codes are made up of alternating series of letters and numbers, separated by periods. If you’re not paying close attention or are in a hurry, it’s easy to place an O where a zero should be or swap a 1 for an I. Accidentally subbing in the wrong letter or number in a coding sequence can change the therapeutic diagnosis code entirely, sending up a red flag to insurers as they process your claim.

3. Leaving Out Laterality and Specificity 

ICD-10  focuses heavily on identifying the laterality and coding to the highest specificity. This focus can make finding the best code a little more time-consuming. But finding the code that’s the best fit for the therapeutic diagnosis and designates which side of the body is affected will help you avoid rejections or denials.

4. Selecting an Incorrect Code 

Lack of familiarity with the full menu of ICD-10 codes that could describe a particular diagnosis can result in choosing the wrong code. You don’t have to know them all, but being well-versed in the codes most frequently used with occupational therapy patients can help avoid time-consuming resubmissions.

5. Incomplete Documentation  

If you enter a treatment diagnosis code, you need to have documentation to justify your choice. Keeping detailed notes of your therapy sessions and recording data from objective assessments of their current levels of functioning makes it easier to justify your choice if it’s ever challenged by an insurer.

Tips for Choosing the Best ICD-10 Code for Occupational Therapy

When you choose the wrong ICD-10 code, incorrect information about a patient goes on the record, making it difficult to show the medical necessity of the treatment you provided. This can lead to billing claims rejections, time-consuming resubmission, and payment delays. Here are some helpful tips to ensure you choose the best ICD-10 code for every patient the first time.

Begin with Documentation 

Assess your patient’s impairments using objective measures and document their current level of functioning in the area you’ll be providing service. Create and document your short and long-term goals for the patient related to the targeted impairment and include them as part of the patient’s plan of care. Select your treatment codes, consulting the code definitions to ensure they match up with the impairment.

Be Sure Treatment is Medically Necessary for the Diagnosis

The code you choose must be medically necessary and directly relate to the service you provided to the patient.

Use Therapy Notes to Support Your ICD-10 Code Choice

Documentation from your therapy notes should support your ICD-10 coding choice. Include information such as dominant side, anatomical details, site specificity, and the affected body part.

Order the Codes by Amount and Complexity of Care

As mentioned before, code to the highest level of specificity, including all of the patient’s current medical conditions and comorbidities related to the current therapy services you’re providing. Order the codes sequentially by the amount and complexity of therapy being provided.

Use Unspecified Codes Sparingly 

There’s certainly a place for using unspecified codes if there’s insufficient information in the patient’s medical record. But unspecified codes tend to get overused in favor of less common, but more specific codes. Using an unspecified code too often can be a red flag for insurers.

Commonly-Used OT ICD-10 Codes

Some ICD-10 codes are more commonly used by occupational therapists than others. Here are ten codes you’re likely to come back to again and again.

Wrapping Up

ICD-10 is the most comprehensive diagnostic coding system to date. It gives occupational therapists the freedom to select diagnostic codes that include a high level of detail about their patient’s condition. But with expanded choices comes an increased risk for coding mistakes. By paying careful attention, becoming familiar with the codes most often used by occupational therapists, and keeping good documentation, you’ll be able to avoid many of the common ICD-10 coding pitfalls.

Check out our Complete Guide to Occupational Therapy Billing to learn more about how to simplify and improve your billing processes.