Occupational therapy billing units

Occupational therapy billing units, OT billing units, billing units for OT, billing units for occupational therapy

Occupational therapy billing units (OT billing units) are one of the many responsibilities of clinicians in practice. Occupational therapy practice is defined by the American Occupational Therapy Association (AOTA) as ‘the therapeutic use of everyday occupations with clients to support participation.’

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These services, generally provided in healthcare settings, will require proper documentation and billing procedures to ensure clients receive quality treatment and that services are reimbursable. 

Billing procedures are frequently updated annually to help therapists ensure their services are medically necessary and reimbursable. 

Billing process basics include:
  • Adequate documentation of services
  • Correct ICD-10 diagnosis
  • Current Procedural Terminology (CPT) codes
  • Charging the correct OT billing units
  • Using the appropriate claim form per insurance provider

Let’s look at the basics of OT billing units and common mistakes to avoid.

OT billing units

Two types of OT billing units used are timed and untimed codes. Untimed codes are commonly used for evaluations and revaluations. Using an untimed code means that you will only charge one unit for the service, no matter how long the service duration.

If your evaluation requires 30 minutes or one hour, you will only charge one unit for the evaluation.

There are three different evaluation codes:
  • Low Complexity (97165) 
  • Moderate Complexity (97166) and 
  • High Complexity (97167)

For all evaluation codes, an occupational profile, medical history, and therapy history needs to be included in the therapy documentation with the code reflecting complexity of the evaluation. 

Definitions used in CPT descriptions for this article can be found in the CPT manual on the CMS website. Insurance companies have respective fee schedules that will provide what your rate is for each of the services commonly billed.

CPT code




Low complexity evaluation

Brief medical history described and current clinical presentation requiring skilled service. Assessments administered identify 1-3 performance deficits that are limiting participation. Typical duration of 30 minutes to complete face to face evaluation. 


Moderate complexity evaluation

Expanded medical history included, and current clinical presentation with additional information provided about cognitive, physical, and psychosocial factors that limit overall functional participation. Assessments administered identify 3-5 performance deficits that are limiting participation. Typical duration of 45 minutes to complete face to face evaluation.


High complexity evaluation

Extensive medical history review with cognitive, physical, and psychosocial factors that limit overall functional participation. Assessments administered identify 5 or more performance deficits that are limiting participation. Typical duration of 60 minutes to complete face to face evaluation.



Untimed code CPT 97168. This is based and established on the current plan of care. Often performed once every 6 months within the same plan of care established at corresponding initial evaluation. Re-evaluation is necessary if functional status changes, significant progress is made, or goals or treatment frequency need to be updated

Timed Billing Units generally follow the “8-minute rule” recognized by CMS. You will need to verify with each insurance provider for timed unit requirements when modifiers are required and if an 8- minute rule is recognized for each timed unit. 

The 8-minute rule means that treatments must have a duration of at least 8 minutes of direct service to be considered billable. OT billing units in the same day are measured in 15-minute increments and follow the limitations listed below. 

The table below lists parameters provided on the Centers for Medicare and Medicaid Services (CMS) website. 

1 unit

8-22 minutes

2 units

23-37 minutes

3 units

38-52 minutes

4 units

53 -67 minutes

Modifiers are used in billing to provide additional information about service units and CPT codes documented in the claim. Modifiers play a crucial element in billing and therapists should remain current on payor requirements for service to support your practice. Some insurance companies require frequent use of modifiers and can result in a claim denial or reduction of payment. Verify with your respective insurance providers on when modifiers are required.

Occupational therapy billing codes

CPT codes stand for Current Procedural Terminology and are updated annually and serve as a standard for reporting procedures using the Healthcare Common Procedural Coding System (HCPCS). Common codes used in occupational therapy practice are listed below. Additional occupational therapy billing codes can be found in more detail within the 2023 CPT.

CPT code




Therapeutic Activity

Direct one-on-one patient contact with use of dynamic activity to improve functional performance, each 15 minutes. 


Self–care/home management training

ADL and IADL training, meal preparation, safety procedures, and assistive technology instruction for each 15 minutes. 


Neuromuscular Re-education

Re-education of movement, balance, coordination, kinesthetic sense, posture, and/or proprioception for seated or standing tasks


Therapeutic Procedure

Therapeutic procedure of one or more areas, for each 15 minutes of therapeutic exercise to develop strength, endurance, range of motion and/or flexibility. 


Manual Therapy Techniques

Including but limited to mobilization, manipulation, and lymphatic drainage to 1 or more regions, each 15 minutes. 


Community/Work Reintegration Training

Shopping, transportation, money management, and work environment analysis, work task analysis and assistive technology training during direct one on one contact each 15 minutes. 

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OT billing units documentation

Once we have the correct codes identified, we need to make sure our OT billing units documentation meets standard requirements. Insurance reviewers need to see your services are medically necessary per the patient's diagnosis and goals. 

Clear documentation uses:
  • Correct codes 

  • Identifies goals addressed during the session

  • Any progress toward set goals

  • Benefits of the intervention

  • Patient response to treatment 

  • Why services should continue to reach full potential 

Describing the whole picture of your session using unclear communication can lead to denial if the reviewer interprets the documentation as services not medically necessary or not supportive of units billed in the claim. 

Documentation should also be completed and signed on time and protected using HIPPA-compliant methods for patient protection. In case of an audit, you must submit requested documentation to prove your services were medically necessary. Additional documentation tips can be found by searching CMS resources for provider guidelines.

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OT billing units guidelines

A great resource for information about standard billing guidelines can be found on the CMS website. Guidelines emphasize proper coding, documentation, and billing to be utilized along with using correct claim forms before reimbursement is rendered. 

Luckily there are software platforms like Theraplatform to assist in the billing process to help therapists manage their own billing. Next, we will discuss common errors to avoid in your claims to increase your chances of reimbursement. 

Frequent OT billing units errors include:
  • Entering incorrect patient data 

  • Wrong claim forms

  • Insufficient documentation 

  • Misspelled patient name

  • Incorrect birthdate

  • Incorrect insurance information 

  • Fortunately, all of these OT billing units errors can be corrected if caught before submission and rejection.

Other common OT billing units errors include duplicate claims submitted on the same day. Ensure your dates of service are correct and aligned with ethical standards. You cannot backdate services on documentation and documentation submitted promptly to avoid two therapists accidentally billing the same treatment codes for the same day. 

Additional guidelines for coding and documenting correctly can be found in your professional organization’s ethical standards resources. These mistakes are avoidable by auditing documentation and informing staff of errors or payment denials.


Tips for successful occupational therapy billing

The tips listed above should help you feel better about OT billing units. If you still have questions about your claims, call the insurance company to confirm if your codes and units are acceptable. 

CPT codes are updated annually, so frequently review changes on the CMS website, American Medical Association Website (AMA), and your professional organization for up-to-date information.

Occupational therapy billing varies across settings, and requirements are updated annually, so be sure to search your specific plan and practice setting requirements when applying the information provided above. 


Theraplatform is a HIPAA-compliant, fully integrated software to help manage your documentation and billing process. TheraPlatform, an all-in-one EHR, practice management and teletherapy tool was built for therapists to help them save time on admin tasks. They offer a free, 30-day trial with no credit card required. Cancel anytime.

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