Modifier CQ is a HCPCS Level II payment modifier used to identify outpatient physical therapy services furnished in whole or in part by a Physical Therapist Assistant (PTA).

The modifier was created following the Bipartisan Budget Act of 2018. Beginning January 1, 2020, Medicare required reporting of Modifier CQ when applicable, and beginning January 1, 2022, applicable services furnished in whole or in part by a PTA became subject to the Medicare payment reduction established by law.

Modifier CQ is not used to identify physical therapy services alone—that is the role of Modifier GP. Instead, CQ identifies that a PTA furnished all or part of the service under a physical therapy plan of care.

Modifier

Modifier Name

Outpatient Physical Therapy Services Furnished in Whole or in Part by a Physical Therapist Assistant (PTA)

Plain English Explanation

Modifier CQ tells Medicare:

“This physical therapy service was furnished entirely or partially by a Physical Therapist Assistant (PTA).”

This allows Medicare to apply the appropriate payment policy.

Purpose of Modifier CQ

Modifier CQ is used to:

Identify services furnished by a PTA.
Apply Medicare’s PTA payment adjustment.
Distinguish PT services performed by a Physical Therapist from those furnished in whole or in part by a PTA.
Ensure compliance with CMS outpatient therapy billing requirements.
Support accurate reimbursement.

Understanding Modifier CQ

A Physical Therapist Assistant (PTA) works under the direction and supervision required by applicable federal and state laws.

When a PTA performs:

The entire therapy service, or
More than the de minimis portion of a service,

Modifier CQ is generally required.

Under current CMS policy, the de minimis standard is generally more than 10% of a service or unit of service furnished by the PTA.

When to Use Modifier CQ

Append Modifier CQ when:

Services are furnished under a physical therapy plan of care.
A PTA furnishes the entire service.
A PTA furnishes more than 10% of a service or unit under the Medicare de minimis policy.
Medicare or another payer requires CQ reporting.

Modifier CQ is reported together with Modifier GP on applicable Medicare claims.

Common CPT codes include:

CPT Code	Description
97110	Therapeutic exercises
97112	Neuromuscular reeducation
97116	Gait training
97140	Manual therapy
97530	Therapeutic activities
97535	Self-care/home management training
97750	Physical performance testing

When NOT to Use Modifier CQ

Do not use Modifier CQ when:

The service is performed entirely by the Physical Therapist.
The PTA’s involvement does not exceed the Medicare de minimis threshold.
The service is occupational therapy (use CO, if applicable).
The service is speech-language pathology.
The service is unrelated to a physical therapy plan of care.

Medicare Rules

Under Medicare:

Modifier CQ must be reported when applicable for outpatient physical therapy services furnished in whole or in part by a PTA.
CQ must be paired with Modifier GP.
The de minimis policy generally applies when the PTA furnishes more than 10% of a service or unit.
Applicable services may receive the statutory PTA payment adjustment under the Medicare Physician Fee Schedule.

Commercial Insurance Rules

Commercial payer policies vary.

Some commercial insurers:

Require Modifier CQ.
Follow Medicare rules.
Do not apply Medicare’s payment adjustment.
Require payer-specific documentation.

Always verify payer requirements before billing.

Documentation Requirements

Documentation should include:

Certified physical therapy plan of care.
Initial evaluation.
Daily treatment notes.
Progress reports.
Minutes performed by the PT and PTA.
Documentation supporting application (or non-application) of the de minimis standard.
Therapist and PTA signatures, where required.

Real Billing Examples

Example 1 – Entire Service by PTA

A PTA performs 30 minutes of therapeutic exercise under a certified physical therapy plan of care.

Billing

CPT 97110
Modifiers GP CQ

Example 2 – Shared Treatment

A Physical Therapist performs 12 minutes of therapeutic exercise and the PTA performs 18 minutes of the same service.

Because the PTA furnished more than 10% of the service, the applicable unit(s) require Modifier CQ according to CMS de minimis rules.

Example 3 – Gait Training

A PTA independently performs gait training.

Billing

CPT 97116
Modifiers GP CQ

Example 4 – Manual Therapy

A PTA performs manual therapy during an outpatient visit.

Billing

CPT 97140
Modifiers GP CQ

Example 5 – Incorrect Use

A licensed Physical Therapist performs the entire treatment session without PTA involvement.

Billing:

CPT 97110
Modifier CQ

This is incorrect because no PTA furnished any portion of the service.

CMS-1500 Claim Example

Field	Example
CPT	97110
Modifier 1	GP
Modifier 2	CQ
Diagnosis Pointer	M25.561 (Example)
Units	2

Common Denial Reasons

Missing Modifier CQ.
Missing Modifier GP.
Incorrect modifier combination.
PTA involvement not documented.
Incorrect application of the de minimis standard.
Documentation inconsistent with billing.
Invalid provider type.

How to Correct the Denial

Review therapist and PTA treatment documentation.
Verify the minutes furnished by each provider.
Apply the Medicare de minimis standard correctly.
Ensure GP and CQ are reported together when required.
Correct the claim and resubmit if appropriate.
Appeal with supporting documentation when necessary.

Coding Tips

Always report GP with CQ for applicable Medicare PT claims.
Document PTA and PT treatment minutes separately.
Understand the Medicare de minimis calculation.
Verify payer-specific requirements for non-Medicare claims.
Maintain detailed treatment records supporting skilled therapy.

Modifier CQ vs Modifier GP

Modifier	Description
CQ	Indicates the PTA furnished all or part of the service
GP	Indicates the service was furnished under a physical therapy plan of care

Modifier CQ vs Modifier CO

Modifier	Description
CQ	Physical Therapist Assistant (PTA)
CO	Occupational Therapy Assistant (OTA)

Modifier CQ vs Modifier GO

Modifier	Description
CQ	PTA services
GO	Occupational therapy plan of care

Modifier CQ vs Modifier GN

Modifier	Description
CQ	Physical therapy assistant services
GN	Speech-language pathology plan of care

Frequently Asked Questions (FAQs)

Q1. What does Modifier CQ mean?

Answer: It identifies outpatient physical therapy services furnished in whole or in part by a Physical Therapist Assistant (PTA).

Q2. Is Modifier CQ always billed with GP?

Answer: Yes. For applicable Medicare physical therapy claims, CQ is reported with GP because GP identifies the physical therapy plan of care, while CQ identifies PTA involvement.

Q3. What is the Medicare de minimis rule?

Answer: Generally, the CQ modifier applies when the PTA furnishes more than 10% of a service or unit of service, as defined by CMS.

Q4. Does Modifier CQ apply to occupational therapy?

Answer: No. Occupational therapy assistant services use Modifier CO.

Q5. Does Modifier CQ affect Medicare payment?

Answer: Yes. Applicable services furnished in whole or in part by a PTA are subject to the Medicare payment adjustment established by federal law.

AR Caller Tips

When following up on claims billed with Modifier CQ:

Verify that GP and CQ were reported together.
Confirm PTA involvement in the medical record.
Review therapist and PTA treatment minutes.
Determine whether the payer applies Medicare PTA payment rules.
Document the payer representative’s name, reference number, and appeal instructions.

Interview Questions

Question 1

What does Modifier CQ indicate?

Answer: It identifies outpatient physical therapy services furnished in whole or in part by a Physical Therapist Assistant (PTA).

Question 2

Which modifier must accompany CQ on Medicare PT claims?

Answer: Modifier GP.

Question 3

What is the Medicare de minimis threshold?

Answer: Generally, when the PTA furnishes more than 10% of a service or unit of service, Modifier CQ applies.

Question 4

Does CQ apply to occupational therapy?

Answer: No. Occupational therapy assistant services require Modifier CO.

Practice Scenario

Scenario

A Medicare beneficiary receives 30 minutes of therapeutic exercise. The Physical Therapist provides 10 minutes, and the PTA provides 20 minutes of the same timed service.

Question

Which modifiers should be appended?

Answer

Report CPT 97110 with Modifiers GP and CQ, because the service was furnished under a physical therapy plan of care and the PTA furnished more than the Medicare de minimis portion of the service.

Related Therapy Modifiers

GP – Services Delivered Under an Outpatient Physical Therapy Plan of Care
GO – Services Delivered Under an Outpatient Occupational Therapy Plan of Care
GN – Services Delivered Under an Outpatient Speech-Language Pathology Plan of Care
CO – Services Furnished in Whole or in Part by an Occupational Therapy Assistant (OTA)
KX – Requirements Specified in the Medical Policy Have Been Met (when applicable)

Common Billing Mistakes

Reporting CQ without GP.
Applying CQ when the PTA did not exceed the de minimis threshold.
Using CQ for occupational therapy services.
Failing to document PT/PTA treatment minutes.
Incorrectly calculating timed units.
Omitting CQ when required.

Key Takeaways

Modifier CQ identifies outpatient physical therapy services furnished in whole or in part by a Physical Therapist Assistant (PTA).
It must be paired with Modifier GP on applicable Medicare claims.
Medicare generally applies CQ when the PTA furnishes more than 10% of a service or unit under the de minimis policy.
Accurate minute tracking and documentation are essential for compliant billing.
Proper use of Modifier CQ helps prevent claim denials and supports correct Medicare reimbursement.

References

CMS Therapy Services
CMS Billing Examples Using CQ/CO Modifiers
CMS Medicare Claims Processing Manual, Chapter 5.
HCPCS Level II Code Book.
CPT® Professional Edition (American Medical Association).

Conclusion

Modifier CQ is an important Medicare payment modifier used to identify outpatient physical therapy services furnished in whole or in part by a Physical Therapist Assistant. Correct application requires understanding the de minimis standard, accurate documentation of therapist and assistant treatment time, and proper pairing with Modifier GP. Consistent compliance with CMS guidelines helps ensure accurate reimbursement, minimizes denials, and supports high-quality outpatient rehabilitation billing.

Educational Disclaimer

This article was prepared with the assistance of artificial intelligence (AI) for educational and informational purposes. It is based on publicly available CMS guidance, Medicare outpatient therapy billing policies, HCPCS Level II guidance, and general medical coding principles. It is not an official publication of CMS or the American Medical Association (AMA). Always consult the latest CMS Medicare Claims Processing Manual, Medicare Benefit Policy Manual, HCPCS Level II Code Book, applicable Local Coverage Determinations (LCDs), National Coverage Determinations (NCDs), and payer-specific billing policies before coding, billing, or submitting claims.