Most Common Codes and Billing Modifiers in Rehab Therapy

Choose the right CPT codes and billing modifiers to increase reimbursements with our guide for physical therapy, occupational therapy, and SLP.
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Adding new therapy services, treating a wider range of patient populations, and expanding to new locations are all good signs for rehabilitation therapy practices. But these markers of growth also mean added complexity when it comes time to get paid.

If you’re here, it’s probably your job to tackle that complexity head-on. Using the right codes and billing modifiers from the start can reduce errors and claim denials, and secure prompt reimbursements for your practice.

You’re not alone! We’ve put together this guide to billing and coding for outpatient occupational therapy, speech-language pathology, and physical therapy.

Understanding Rehabilitation Therapy Billing

Some types of billing are simple. For example, when you order in a restaurant, you expect your check to reflect exactly what you selected. There’s a finite menu of choices and customizations, so it’s easy to map your bill to what you purchased.

Unfortunately, that’s not how things work in healthcare. There are thousands of conditions and vast numbers of treatment possibilities—and no two patients are alike. Physical therapists, occupational therapists, and speech-language pathologists who serve varied demographics and treat a breadth of conditions may find billing especially arduous.

The good news is that the billing process itself follows a predictable flow of events. 

The billing cycle kicks off when your patients register for services and provide insurance information. Often, insurances will require a physician referral and prior authorization for service coverage. However, the tide is changing in some states that allow direct access, in which referrals are not required for a certain number of appointments.

When a patient attends an appointment, your practice must determine financial responsibility by assessing what services insurance covers. If some services are not covered, you should inform the patient to expect a bill for any outstanding balance.

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After a patient’s visit is complete, your team translates medical reports detailing services provided into diagnostic and treatment codes for billing. This is where things start to get tricky. Medical billing codes cover almost every type of ailment and treatment imaginable so that bills can get very detailed very quickly.

On a typical bill for US healthcare consumers, you may find one or more of three types of standard billing codes:

  • International Classification of Diseases (ICD) codes, developed by the World Health Organization (WHO), with a US version created by the Centers for Medicare and Medicaid Services (CMS) and the National Center for Healthcare Statistics (NCHS).

  • Current Procedure Terminology (CPT) codes developed by the American Medical Association (AMA)

  • Healthcare Common Procedure Coding System (HCPCS) codes, developed by CMS.

After coding is complete, you are then ready to generate a claim and submit it to the patient’s insurer for processing. The insurer will then review the claim, determine what services are covered, and pay for those services. Patients are responsible for any services not covered by their insurance.

Commonly Used Modifiers in Rehabilitation Therapy Billing

PT, OT, and SLP practitioners use CPT and HCPCS codes to bill for specific procedures or services. While CPT codes include five numbers, HCPCS codes are alphanumeric, with one letter and four numbers. 

Both CPT and HCPCS codes may include a modifier: a two-digit number affixed to the end of the code that gives the insurers more information to adjust payments. Modifiers indicate that a service or procedure has been altered for some reason but not fundamentally changed in definition or scope. They appear at the end of CPT or HCPCS codes. 

Rehabilitation therapy practices use these types of modifiers most frequently: 

  • GP/GO/GCN Modifier. These modifiers apply only to codes for physical, occupational, and speech-language therapy.

  • KX Modifier. This modifier indicates that services for the patient have met the annual Medicare capped amount but that the clinician attests to the medical necessity of continued care.

  • GA Modifier. A GA modifier indicates that a provider believes that the service may not meet Medicare standards for medically necessary care and that an Advance Beneficiary Notice (ABN) is on file, allowing the provider to bill the patient if Medicare denies the claim.

  • 59 Modifier. This modifier indicates that the noted service is separate and distinct from another service provided on the same day.

Knowing how to apply common codes and billing modifiers can simplify your revenue processes and help you maximize your therapy payments.

Using CPT Codes for Rehabilitation Therapy Billing

There are over 10,000 CPT codes—but, thankfully, you don’t need to know them all. Instead, you should familiarize yourself with the most commonly used codes and billing modifiers for rehabilitation therapy.

Physical and Occupational Therapy CPT Codes

  • 95992 Canalith repositioning procedure

  • 97012 Mechanical traction therapy

  • 97016 Vasopneumatic device therapy

  • 97018 Paraffin bath therapy

  • 97022 Whirlpool therapy

  • 97024 Diathermy 

  • 97028 Ultraviolet therapy

  • 97032 Electrical stimulation

  • 97033 Electric current therapy

  • 97034 Contrast bath therapy

  • 97035 Ultrasound therapy

  • 97036 Hydrotherapy

  • 97039 Unlisted modality

  • 97110 Therapeutic exercises

  • 97112 Neuromuscular reeducation

  • 97113 Aquatic therapy/exercises

  • 97116 Gait training therapy

  • 97124 Massage therapy

  • 97129 Therapeutic interventions 1st 15 minutes

  • 97130 Therapeutic interventions each additional 15 minutes

  • 97139 Unlisted therapeutic procedures

  • 97140 Manual therapy 1/> regions

  • 97150 Group therapeutic procedures

  • 97161 Physical therapy evaluation low complexity; 20 minutes

  • 97162 Physical therapy evaluation moderate complexity; 30 minutes

  • 97163 Physical therapy evaluation high complexity; 45 minutes

  • 97164 Physical therapy re-evaluation to establish a plan of care

  • 97165 Occupational therapy evaluation low complexity; 30 min

  • 97166 Occupational therapy evaluation moderate complexity; 45 minutes

  • 97167 Occupational evaluation high complexity; 60 minutes

  • 97168 Occupational therapy re-evaluation to establish a plan of care

  • 97530 Therapeutic activities

  • 97533 Sensory integration

  • 97535 Self-care management training

  • 97537 Community/work reintegration

  • 97542 Wheelchair management training

  • 97750 Physical performance test

  • 97755 Assistive technology assessment

  • 97760 Orthotic management and training; 1st encounter

  • 97761 Prosthetic training; 1st encounter

  • 97763 Orthotic/prosthetic management subsequent encounter

  • 97799 Unlisted physical medical/rehabilitation procedure

  • G0283 Electrical stimulation other than wound

Speech Therapy CPT Codes

  • 92507 Speech/hearing therapy (individual)

  • 92508 Speech/hearing therapy (group)

  • 92521 Evaluation of speech fluency

  • 92522 Evaluate speech production

  • 92523 Speech sound language comprehension

  • 92524 Behavioral quality analysis voice

  • 92597 Oral speech device evaluation

  • 92607 Evaluation for a prescription for speech-generating augmentative and alternative communication device, face-to-face with the patient; first hour

  • 92608 Evaluation for a prescription for speech-generating augmentative and alternative communication device, face-to-face with the patient

  • 92609 Use of speech device service

  • 96105 Assessment of aphasia

  • 96112 Developmental test administration; first hour

  • 96113 Developmental test administration; additional 30 minutes

  • 96125 Standardized cognitive performance testing per hour

  • 97110 Therapeutic exercises

  • 97129 Therapeutic interventions that focus on cognitive function; initial 15 minutes.

  • 97130 Therapeutic interventions that focus on cognitive function; each additional 15 minutes

  • 97530 Therapeutic activities

  • 97533 Sensory integration

  • 97535 Self-care management training 

What Are CCI Edits?

The Centers for Medicare and Medicaid Services (CMS) National Correct Coding Initiative (NCCI) advocates proper medical coding to reduce errors and decrease improper payments. The automated NCCI system manages Correct Coding Initiative (CCI) edits, which are CPT code pairs that identify when a provider can not bill for services performed for the same patient on the same day.

The NCCI system address billing of two categories of CPT code pairs:

  • Mutually exclusive code pairs. These represent services that cannot reasonably be performed on a patient during a single care encounter.

  • Component services. These may not be reported with CPT codes that indicate more comprehensive services.

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Telehealth Billing in Rehabilitation Therapy

During the global Covid-19 pandemic, telehealth took off. When the US public health emergency (PHE) ended on May 11, 2023, some uncertainty emerged around the future of telehealth in rehabilitation therapy. Fortunately, the Consolidation Appropriations Act (CAA) of 2023 allows many of the pandemic-era waivers for telehealth services to remain in place through the end of calendar year 2024 for Medicare patients

Telehealth coverage for Medicaid patients varies by state, and private insurers set their own policies regarding telehealth. Before billing any payer for telehealth, you should confirm their specific processes and coding requirements to minimize the risk of denial.

Telehealth has its own set of unique CPT modifiers. Here are the ones rehabilitation therapists are most likely to use:

  • 95. Synchronous telemedicine service rendered via a real-time interactive audio and video communications system.

  • GQ. Telehealth service rendered via asynchronous telecommunications system.

  • GT. Telehealth service rendered via interactive audio and video telecommunications systems.

  • FQ. A telehealth service was furnished using real-time audio-only communication technology.

Common Mistakes in Billing for PT, OT, and SLP Services

Billing mistakes can increase administrative hassles, slow payments, or harm relationships with patients. That’s why knowing common billing pitfalls and how to avoid them is essential.

  • Missing Modifiers. Some insurers may want you to append GP, GO, and GN modifiers to every code to specify the type of therapy performed. Overlooking these codes can result in denials or delays. You also need to apply the 59 modifier indicating linked services to one code in a pair. Also, suppose you’re using the KX modifier to indicate medically necessary services above an annual Medicare cap. In that case, you should apply it to all billed services above the cap to gain reimbursement.

  • Overusing the Therapeutic Exercise Code. Many therapists use code 97110 as a catch-all since it’s broad enough to cover a wide range of activities. But there are a few problems with this approach. First, the services you’re providing might be a better fit for the therapeutic activity code (97530), which has a higher reimbursement rate. Note: Payers may question your use of 97110 if they feel you are over-reliant on it.

  • Lack of Verification. It’s wise to re-verify insurance coverage frequently—and always if a patient has had a gap in care. You never want to provide services while believing a patient has coverage, only to find out that’s not the case. Otherwise, you’re on the path to claim denial, and may even risk losing your patient over an avoidable snafu.

  • Administrative Errors. Something as simple as two transposed digits in a claim code can lead to major billing headaches. You face frustrating denials and tedious manual work to uncover the issue. Instead of quick payments, you must play a waiting game until your well-earned reimbursements arrive. Using specialized billing software with automated claim scrubbing can help you avoid these missteps.

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Frequently Asked Questions about Billing for Outpatient Therapy Services

Governed by the American Medical Association, CPT codes identify specific services or procedures performed. The AMA has a CPT editorial panel that reviews requests for additions or revisions to CPT codes.


ICD-10 refers to codes in the International Classification of Diseases, 10th edition. Practitioners use ICD-10 codes to report conditions and diagnoses.

Healthcare providers use CPT codes to report on diagnostic, medical, or surgical services or procedures provided. Segmented into three categories (Level I, Level II, Level III), CPT codes are used universally for medical billing and are recognized by both private and government payors.

In addition, healthcare practitioners use HCPCS codes to report medical procedures to Medicare, Medicaid, and other health insurance providers. While Level I HCPCS codes are used universally, Level II codes cover products, supplies, and services not addressed by CPT codes and are primarily used for billing to Medicare and Medicaid. Some private insurers recognize Level II HCPCS codes. 

Timed CPT codes represent skilled time spent working one-on-one with a patient and can be billed multiple times per session. Each timed code represents 15-minute increments of care.

Practitioners may only bill one untimed CPT code per session—regardless of the time spent with the patient. In these scenarios, the practitioner bills a pre-determined fee that does not reflect the actual time spent providing care.

The 8-minute rule is related to to timed CPT codes. Since care does not always fit into precise 15-minute service blocks, the 8-minute rule helps providers clarify appropriate billing scenarios. When providers spend more than eight minutes providing a service to patients, they can bill for the full 15 minutes.

To understand how to bill for a timed session of care, total up the entire time spent and divide by 15. If the remainder is greater than eight, providers can bill for an additional service unit.

CPT codes are the designated standard for electronic reporting by care providers under the Health Insurance Portability and Accountability Act (HIPAA). As such, the AMA actively reviews and updates them to maintain currency and accuracy. The AMA CPT Editorial Panel meets three times per year to evaluate potential CPT code changes and updates. 

The AMA updates CPT codes once yearly, with new codes taking effect on January 1. The AMA publishes a new CPT code book each fall to ensure a smooth implementation of any new or changed codes. 

Billing Software for Rehabilitation Therapy

As a billing specialist, your role isn’t going to get any less complex any time soon.

But you can simplify your workflows with Raintree’s advanced billing software for PT, OT, SLP, and multi-specialty therapy practices.

Created specifically to reduce the administrative burden on outpatient therapy practices, Raintree drives up to 40% billing cycle improvement with features like auto-coding edits by location, payor, provider, and more. We also provide an all-in-one payment processing solution that helps practices eliminate manual entry tasks, secure revenue faster, and create a modern patient experience.

Ready to see what Raintree can do? Let’s connect.

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