Medical coding modifiers serve as specialized tools to communicate the precise circumstances under which a procedure or service was performed. These two-character codes, often appended to a primary Current Procedural Terminology (CPT) code, provide additional information without altering the definition of the original service. This critical layer of detail informs payers, such as Medicare, about variations in service provision, including the professional who delivered the service. In the context of rehabilitation, a specific set of modifiers signals unique conditions related to the delivery of physical, occupational, and speech-language therapy.
Defining Modifier 97 and Applicable Services
Modifier 97 is officially defined as “Rehabilitative Services” within the CPT coding system, used to differentiate rehabilitative care from habilitative care (Modifier 96). Rehabilitative services aim to restore a patient’s function or skill that was lost or impaired due to injury or illness. However, the billing policy for therapy assistants does not use the two-digit Modifier 97 for payment reduction, but rather two separate HCPCS modifiers.
The two modifiers implemented by the Centers for Medicare & Medicaid Services (CMS) to track services provided by therapy assistants are CQ for physical therapist assistants (PTAs) and CO for occupational therapy assistants (OTAs). These modifiers apply specifically to CPT codes designated for outpatient physical therapy and occupational therapy services. The requirement for these payment modifiers does not currently extend to speech-language pathology assistant (SLPA) services under the same federal mandate.
The CQ and CO modifiers must be applied to all applicable physical and occupational therapy CPT codes, including therapeutic exercises (97110), therapeutic activities (97530), and manual therapy techniques (97140). Their function is to signal that the service was furnished “in whole or in part” by a PTA or OTA. This reporting requirement arose from the Bipartisan Budget Act of 2018, which mandated a payment adjustment for these specific services.
Understanding Supervision Requirements for Use
The application of the CQ and CO modifiers is directly tied to the concept of independent service provision by the assistant, rather than the general supervision level required by the state. The modifier is mandated when the therapy assistant performs more than a minimal portion of a service independently of the supervising therapist. CMS established a “de minimis” standard to define this threshold of independent performance.
For a timed CPT code, the modifier is required when the PTA or OTA independently furnishes more than 10 percent of the total time for a specific 15-minute unit of service. For example, if a timed service is billed for one unit, the assistant must have provided more than 1.5 minutes of that unit without the therapist’s concurrent involvement. This standard applies to the minutes of the service delivered solely by the assistant.
The core trigger for the modifier is the assistant’s independent action, not the overall level of supervision, such as “general” or “direct.” These are separate regulatory requirements that govern the practice setting. State practice acts define the level of supervision the therapist must maintain over the assistant, such as being available by phone (general supervision) or physically present in the clinic (direct supervision).
The CQ/CO modifiers are applied in addition to the discipline-specific modifiers—GP for physical therapy or GO for occupational therapy. These modifiers indicate the service was performed under a plan of care.
To prevent the modifier from being applied to a final unit of a multi-unit service, CMS introduced an exception based on the “8-minute rule” for timed services. If the supervising therapist provides eight or more minutes of the final 15-minute unit, that unit is billed without the assistant modifier. This policy ensures that the therapist’s professional time, which is more than half of the unit, determines the billing status of that final unit.
Impact on Claim Submission and Reimbursement
The primary consequence of appending the CQ or CO modifier to a claim line is the mandated reduction in payment from Medicare. Services identified with the assistant modifier are subject to a payment rate of 85 percent of the amount that would otherwise be paid for the service. This reduction, effective since January 1, 2022, is a direct result of the Bipartisan Budget Act of 2018 legislation.
When submitting a claim, the modifier must be attached to the specific CPT code line that meets the de minimis standard for the assistant’s independent service. For instance, a physical therapy service provided by a PTA that exceeds the 10 percent threshold must be billed with both the GP and CQ modifiers. The use of this dual-modifier system signals to the payer the discipline of the service and the professional who delivered it, thereby triggering the 15 percent payment adjustment.
Other payers, including private insurance companies, often adopt or mirror Medicare’s coding and reimbursement policies. Proper application of these modifiers is necessary not only for compliance with federal law but also to ensure the correct calculation of the allowed amount for the service.