Modifier GO is a HCPCS Level II informational modifier used to identify services that are provided under an outpatient Occupational Therapy (OT) plan of care. Medicare, Medicare Advantage plans, Medicaid programs, and many commercial insurers require Modifier GO on applicable therapy claims to distinguish occupational therapy services from physical therapy and speech-language pathology services.

Modifier GO does not change the payment amount by itself. Instead, it tells the payer that the billed service is part of a certified outpatient occupational therapy plan of care and should be processed under the appropriate occupational therapy benefit.

Failure to append Modifier GO when required may result in claim denials, claim rejections, payment delays, or incorrect processing.

Modifier

Modifier Name

Services Delivered Under an Outpatient Occupational Therapy Plan of Care

Plain English Explanation

Modifier GO tells the payer:

“This service was furnished under an outpatient occupational therapy plan of care.”

It identifies the therapy discipline responsible for the service and helps the payer apply the correct occupational therapy billing rules.

Purpose of Modifier GO

Modifier GO is used to:

Identify outpatient occupational therapy services.
Distinguish occupational therapy from physical therapy and speech-language pathology.
Apply Medicare outpatient rehabilitation billing policies.
Route claims through the correct therapy benefit.
Support accurate reimbursement and regulatory compliance.

Understanding Modifier GO

Occupational therapy helps patients improve or regain the ability to perform activities of daily living (ADLs) and instrumental activities of daily living (IADLs) after illness, injury, surgery, or disability.

Occupational therapists focus on improving:

Dressing
Bathing
Grooming
Feeding
Fine motor coordination
Upper extremity function
Cognitive skills
Home safety
Adaptive equipment use
Functional independence

Modifier GO identifies that the billed CPT or HCPCS service is furnished as part of an occupational therapy treatment program.

When to Use Modifier GO

Append Modifier GO when:

The service is furnished under an outpatient occupational therapy plan of care.
The treatment is provided by a qualified occupational therapist or under applicable supervision rules.
Medicare or another payer requires therapy discipline modifiers.
Medical necessity and skilled therapy requirements are met.

Common CPT codes billed with Modifier GO include:

CPT Code	Description
97165	Occupational therapy evaluation – low complexity
97166	Occupational therapy evaluation – moderate complexity
97167	Occupational therapy evaluation – high complexity
97168	Occupational therapy re-evaluation
97110	Therapeutic exercises
97530	Therapeutic activities
97535	Self-care/home management training
97112	Neuromuscular reeducation

Important: Some CPT codes (such as 97110 or 97530) may be reported by different therapy disciplines. The therapy modifier (GP, GO, or GN) identifies the applicable plan of care.

When NOT to Use Modifier GO

Do not use Modifier GO when:

The service is provided under a physical therapy plan of care (use GP).
The service is provided under a speech-language pathology plan of care (use GN).
The service is not therapy.
The payer does not require therapy modifiers (if applicable under payer policy).

Medicare Rules

Under Medicare:

Modifier GO identifies outpatient occupational therapy services.
Services must be furnished under a certified occupational therapy plan of care.
Documentation must support medical necessity.
Occupational therapists must establish, maintain, and update treatment goals.
Progress reports and treatment documentation must comply with Medicare rehabilitation requirements.
Claims remain subject to Medicare therapy documentation standards and targeted medical review policies, when applicable.

Commercial Insurance Rules

Commercial payer requirements vary.

Many insurers:

Require Modifier GO.
Follow Medicare rehabilitation policies.
Require prior authorization.
Apply visit limitations.
Require physician referrals.
Have payer-specific documentation standards.

Always verify payer-specific billing requirements.

Documentation Requirements

Documentation should include:

Initial occupational therapy evaluation.
Certified plan of care (when required).
Physician or qualified practitioner certification.
Functional goals.
Progress reports.
Daily treatment notes.
Objective outcome measurements.
Medical necessity documentation.
Therapist signature and credentials.

Real Billing Examples

Example 1 – Occupational Therapy Evaluation

A patient undergoes an initial occupational therapy evaluation following a wrist fracture.

Billing

CPT 97166
Modifier GO

Example 2 – Self-Care Training

An occupational therapist teaches dressing and bathing techniques after shoulder surgery.

Billing

CPT 97535
Modifier GO

Example 3 – Therapeutic Activities

An occupational therapist provides therapeutic activities to improve fine motor coordination after a stroke.

Billing

CPT 97530
Modifier GO

Example 4 – Neuromuscular Reeducation

A patient receives neuromuscular reeducation to improve upper extremity coordination.

Billing

CPT 97112
Modifier GO

Example 5 – Incorrect Use

A physical therapist bills:

CPT 97110
Modifier GO

This is incorrect because the service was furnished under a physical therapy plan of care. Modifier GP should be reported instead.

CMS-1500 Claim Example

Field	Example
CPT	97535
Modifier	GO
Diagnosis Pointer	S52.501D (Example)
Units	2

Common Denial Reasons

Missing Modifier GO.
Incorrect therapy modifier.
Plan of care not certified.
Insufficient medical necessity documentation.
Missing progress reports.
Prior authorization not obtained.
Therapy visits exceed payer limitations.
Incorrect provider specialty.

How to Correct the Denial

Verify the therapy discipline.
Confirm that the occupational therapy plan of care is complete.
Add Modifier GO if omitted.
Verify medical necessity documentation.
Obtain missing authorization if applicable.
Submit a corrected claim.
Appeal with supporting therapy documentation when appropriate.

Coding Tips

Use GO only for occupational therapy services.
Verify the therapy discipline before billing.
Maintain complete treatment documentation.
Document measurable functional improvement.
Verify payer-specific therapy modifier requirements.
Keep evaluations and progress reports current.

Modifier GO vs Modifier GP

Modifier	Description
GO	Occupational Therapy
GP	Physical Therapy

Modifier GO vs Modifier GN

Modifier	Description
GO	Occupational Therapy
GN	Speech-Language Pathology

Modifier GO vs Modifier CO

Modifier	Description
GO	Occupational Therapy Plan of Care
CO	Services furnished in whole or in part by an Occupational Therapy Assistant (OTA)

Important: GO and CO may both be required when occupational therapy services are furnished in whole or in part by an OTA, subject to Medicare and payer-specific billing rules.

Modifier GO vs Modifier CQ

Modifier	Description
GO	Occupational Therapy
CQ	Services furnished in whole or in part by a Physical Therapist Assistant (PTA)

Frequently Asked Questions (FAQs)

Q1. What does Modifier GO mean?

Answer: It identifies services furnished under an outpatient occupational therapy plan of care.

Q2. Is Modifier GO required by Medicare?

Answer: Yes. Medicare generally requires Modifier GO on applicable outpatient occupational therapy services.

Q3. Can GO and CO be billed together?

Answer: Yes. When an occupational therapy service is furnished in whole or in part by an Occupational Therapy Assistant (OTA), both GO and CO may be required depending on Medicare and payer rules.

Q4. Does Modifier GO affect payment?

Answer: Modifier GO is primarily informational. It identifies the therapy discipline so the payer can apply the correct therapy benefit and reimbursement rules.

Q5. Can Modifier GO be used for physical therapy?

Answer: No. Physical therapy services require Modifier GP.

AR Caller Tips

When working claims involving Modifier GO:

Verify the therapy discipline.
Confirm the occupational therapy plan of care is certified.
Review prior authorization status.
Check visit limitations.
Verify documentation supports medical necessity.
Record the payer representative’s name, reference number, and appeal instructions.

Interview Questions

Question 1

What does Modifier GO indicate?

Answer: The service was furnished under an outpatient occupational therapy plan of care.

Question 2

Which modifier identifies physical therapy services?

Answer: Modifier GP.

Question 3

Which modifier identifies services furnished in whole or in part by an Occupational Therapy Assistant (OTA)?

Answer: Modifier CO.

Question 4

Can the same CPT code be billed with different therapy modifiers?

Answer: Yes. CPT codes such as 97110, 97112, and 97530 may be billed by different therapy disciplines. The modifier (GP, GO, or GN) identifies the applicable plan of care.

Practice Scenario

Scenario

A patient recovering from a hand injury attends occupational therapy. The occupational therapist performs therapeutic activities and self-care training to improve fine motor coordination and independence with daily activities.

Question

Which modifier should be appended?

Answer

Report the applicable CPT codes (97530 and 97535) with Modifier GO because the services were furnished under an outpatient occupational therapy plan of care.

Related Therapy Modifiers

GP – Services Delivered Under an Outpatient Physical 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)
CQ – Services Furnished in Whole or in Part by a Physical Therapist Assistant (PTA)
KX – Requirements Specified in the Medical Policy Have Been Met (when applicable)
59 – Distinct Procedural Service (when appropriate)

Common Billing Mistakes

Omitting Modifier GO.
Using GP instead of GO.
Using GN instead of GO.
Missing plan of care certification.
Insufficient documentation of skilled therapy.
Missing progress reports.
Incorrect provider specialty.
Billing non-therapy services with GO.

Key Takeaways

Modifier GO identifies services furnished under an outpatient occupational therapy plan of care.
It distinguishes occupational therapy from physical therapy and speech-language pathology.
Medicare generally requires GO on applicable outpatient occupational therapy services.
Complete documentation and a certified plan of care are essential for compliant billing.
Proper use of Modifier GO helps reduce denials and supports accurate reimbursement.

References

CMS Medicare Claims Processing Manual, Chapter 5 – Part B Outpatient Rehabilitation Services.
CMS Medicare Benefit Policy Manual, Chapter 15 – Covered Medical and Other Health Services.
CMS Therapy Services Educational Materials.
HCPCS Level II Code Book.
CPT® Professional Edition (American Medical Association).

Conclusion

Modifier GO is an essential therapy modifier that identifies services furnished under an outpatient occupational therapy plan of care. It enables Medicare and other payers to recognize the therapy discipline, apply the correct coverage rules, and process claims accurately. Proper documentation, adherence to the certified plan of care, and correct use of Modifier GO help ensure regulatory compliance, timely reimbursement, and high-quality patient care.

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 rehabilitation 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, CPT® Professional Edition, 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.