Medicare • Speech-Language Pathology • Rehabilitation

Modifier GN

Speech-Language Pathology Plan of Care

A complete practical guide to Modifier GN for medical billers, coders, AR callers, speech-language pathology practices and Revenue Cycle Management teams.

Learn what GN means, when it is used, how it differs from GO and GP, common billing mistakes, documentation considerations and how to investigate Medicare SLP denials.

Start Learning Quick Cheat Sheet

Speech-Language Pathology Services delivered under an outpatient speech-language pathology plan of care

Modifier GN at a Glance

The essential facts every Medicare billing professional should know.

Speech-Language Pathology

GN identifies applicable services delivered under an outpatient speech-language pathology plan of care.

POC

Plan of Care

The modifier identifies the speech-language pathology discipline under which the applicable service is delivered.

CMS

Medicare Rule

CMS uses discipline-specific modifiers for applicable outpatient rehabilitation therapy services.

Denial Tool

AR teams can use GN knowledge to investigate therapy modifier, discipline and claim-processing denials.

What Is Modifier GN?

Understand the Medicare definition first, then apply it to actual billing situations.

Official Medicare Meaning

Services delivered under an outpatient speech-language pathology plan of care.

Plain-English Explanation

Modifier GN tells Medicare that the applicable therapy service is being furnished under an outpatient speech-language pathology plan of care.

It is a discipline-specific modifier. It does not mean that every service performed by an SLP automatically requires GN.

Easy memory: GN = Speech-Language Pathology Plan of Care.

GN vs GO vs GP

Medicare uses discipline-specific modifiers for the three major outpatient rehabilitation therapy disciplines.

Speech-Language Pathology

Services delivered under an outpatient speech-language pathology plan of care.

Occupational Therapy

Services delivered under an outpatient occupational therapy plan of care.

Physical Therapy

Services delivered under an outpatient physical therapy plan of care.

GN = SLP | GO = OT | GP = PT

Four Core Concepts Behind GN

Master these points before working a speech-language pathology claim.

Therapy Service

The billed service must be an applicable Medicare therapy service.

SLP Discipline

GN identifies the speech-language pathology discipline under the applicable plan of care.

Correct Modifier

GN distinguishes SLP services from occupational and physical therapy services.

Correct Claim

The claim must also meet Medicare’s applicable coding, documentation and payment requirements.

When Should Modifier GN Be Used?

Use GN when the applicable service is delivered under an outpatient speech-language pathology plan of care.

✓

Outpatient SLP

The service is furnished as part of an outpatient speech-language pathology plan of care.

✓

Applicable Therapy Code

The billed CPT or HCPCS code is included in the applicable Medicare therapy requirements.

✓

SLP Discipline

The service belongs to speech-language pathology rather than physical or occupational therapy.

✓

Medicare Therapy Billing

The claim is being submitted under Medicare rules that require the applicable discipline-specific modifier.

Important

GN should not be added simply because a speech-language pathologist performed a service. Verify the exact CPT/HCPCS code against the current Medicare therapy code list and confirm the applicable plan of care.

When Should You NOT Use Modifier GN?

Do not use GN as a generic label for every service involving communication, cognition or speech.

Not an SLP Plan of Care

Do not use GN when the service is not furnished under an applicable speech-language pathology plan of care.

Physical Therapy

PT services under a PT plan of care use GP rather than GN.

Occupational Therapy

OT services under an OT plan of care use GO rather than GN.

Non-Therapy Service

A non-therapy code does not become an SLP service simply because GN is appended.

Nutrition Therapy

Nutrition services are not represented as SLP therapy services by adding GN.

Respiratory Therapy

Respiratory therapy services should not be represented using GN as an SLP therapy modifier.

Modifier GN Decision Path

A quick decision process for speech-language pathology billing.

Service?

Identify the exact CPT/HCPCS code.

Therapy Code?

Verify applicable Medicare therapy status.

SLP POC?

Confirm speech-language pathology plan of care.

GN?

Apply GN when required.

Verify

Check CMS and MAC requirements.

GN vs Other Common Therapy Modifiers

The discipline modifier should match the applicable plan of care.

GN

Speech-language pathology plan of care.

Identifies SLP discipline.
Used with applicable therapy services.
Not interchangeable with GO or GP.

GO

Occupational therapy plan of care.

Identifies OT discipline.
Used with applicable OT services.
Not interchangeable with GN.

GP

Physical therapy plan of care.

Identifies PT discipline.
Used with applicable PT services.
Not interchangeable with GN.

KX

Therapy threshold / medical necessity.

Different purpose from GN.
Does not identify therapy discipline.
Must meet separate CMS requirements.

GN identifies the SLP plan of care. KX does not replace GN.

Therapy Modifier Comparison Table

Quick reference for Medicare outpatient rehabilitation billing.

Modifier	Discipline / Purpose	Meaning	Key Reminder
GN	Speech-Language Pathology	Services delivered under an outpatient speech-language pathology plan of care.	SLP discipline.
GO	Occupational Therapy	Services delivered under an outpatient occupational therapy plan of care.	OT discipline.
GP	Physical Therapy	Services delivered under an outpatient physical therapy plan of care.	PT discipline.
KX	Therapy threshold / medical necessity	Indicates that applicable medical-necessity and documentation requirements for services above the therapy threshold have been met.	Does not identify SLP discipline.
CO	Occupational Therapy Assistant	Identifies applicable outpatient OT services furnished in whole or in part by an OTA.	OT assistant modifier, not SLP.

Complete Modifier GN Billing Workflow

A practical workflow for speech-language pathology billing teams.

1 Identify the patient’s Medicare coverage and claim setting.

2 Confirm that the service is speech-language pathology.

3 Verify the exact CPT/HCPCS code.

4 Confirm that the service is furnished under the outpatient speech-language pathology plan of care.

5 Verify the current Medicare therapy code list.

6 Apply GN when required.

7 Verify other applicable modifiers and claim requirements.

8 Submit the claim and monitor adjudication.

9 Review ERA/EOB and identify the exact denial reason.

10 Correct, rebill or appeal based on the actual root cause.

Modifier GN Practical Examples

Real-world scenarios for medical billing and AR teams.

Example 1 — SLP Plan of Care

A Medicare beneficiary receives an applicable outpatient speech-language pathology service under the established SLP plan of care.

Billing Concept

Report the applicable therapy service with GN when Medicare requires the discipline-specific therapy modifier.

Example 2 — Physical Therapy

The patient receives an applicable service under a physical therapy plan of care.

Do Not Use GN

The applicable discipline-specific modifier is GP, not GN.

Example 3 — Occupational Therapy

An applicable service is furnished under an outpatient occupational therapy plan of care.

Use the Correct Discipline

GO represents the OT plan of care. GN should not be substituted.

Example 4 — Applicable SLP Code

An SLP furnishes an applicable therapy service under the outpatient SLP plan of care.

Modifier Concept

GN identifies the service as being delivered under the SLP plan of care.

Example 5 — Non-Therapy Code

A non-therapy service is submitted with GN simply because an SLP performed the service.

Modifier Alone Does Not Change the Service

GN should not be used to convert a non-therapy service into an SLP therapy service.

Example 6 — Wrong Discipline Modifier

A claim contains GO even though the service was furnished under a speech-language pathology plan of care.

Root Cause

The discipline-specific modifier does not match the plan of care. The billing team should verify the actual therapy discipline before correcting the claim.

AR Caller Workflow for a GN Denial

A practical process for investigating Medicare speech-language pathology claims.

Review ERA/EOB

Identify the denied claim line and exact Medicare message.

Capture CARC/RARC

Document the adjustment and remark codes before deciding on the next action.

Verify GN

Confirm whether GN was reported on the affected therapy line.

Check CPT/HCPCS

Verify whether the code is an applicable Medicare therapy service.

Verify Plan of Care

Confirm that the service was furnished under the speech-language pathology plan of care.

Check Discipline

Make sure the service belongs to SLP and not PT or OT.

Review KX

If applicable, determine whether therapy threshold and KX requirements are relevant to the denial.

Review CMS/MAC Policy

Verify the current Medicare therapy rule for the exact code and setting.

Correct or Appeal

Select the appropriate action based on the actual denial cause.

Medicare AR Call Script — Modifier GN

Questions to use when investigating an SLP claim.

“I’m calling regarding a Medicare outpatient speech-language pathology claim.”

“Could you please confirm the exact reason the therapy claim line was denied?”

“Can you provide the CARC and RARC codes associated with the denial?”

“Can you confirm whether the denial is related to the GN therapy modifier?”

“Can you confirm whether the billed HCPCS/CPT code requires a discipline-specific therapy modifier?”

“Can you confirm whether GN is the correct modifier for this speech-language pathology plan of care?”

“Can you confirm whether the claim was processed under the appropriate outpatient therapy benefit?”

“Is the denial related to the therapy threshold or KX modifier requirement?”

“Would Medicare require a corrected claim or an appeal for this denial?”

“May I have the call reference number and representative ID for our documentation?”

Common Root Causes of GN-Related Denials

Find the process failure instead of simply rebilling.

GN Missing

An applicable speech-language pathology service was submitted without the required discipline-specific modifier.

Wrong Therapy Modifier

GO or GP was used even though the service was delivered under an SLP plan of care.

Non-Therapy Code

GN was appended to a service that is not an applicable therapy service.

Wrong Plan of Care

Documentation does not support the service being furnished under the SLP plan of care.

KX Issue

Applicable therapy-threshold requirements may not have been properly addressed.

Claim Setting Error

The service may have been billed under a setting or claim configuration that does not match the applicable Medicare requirements.

Common Modifier GN Mistakes

Errors that can lead to claim rejection, denial or unnecessary AR.

Thinking GN Means Any SLP Service

GN identifies applicable services delivered under an outpatient SLP plan of care.

Using GN for PT

Physical therapy services use GP when the applicable Medicare therapy modifier is required.

Using GN for OT

Occupational therapy services use GO when the applicable Medicare therapy modifier is required.

Ignoring the Therapy Code List

Not every CPT or HCPCS code becomes a therapy service simply because GN is appended.

Confusing GN With KX

GN identifies the SLP discipline. KX addresses separate therapy-threshold requirements.

Rebilling Without Root Cause

A corrected claim should address the actual error rather than simply repeat the original submission.

Ignoring Documentation

The claim modifier does not replace the need for documentation supporting the service.

Ignoring MAC Guidance

Medicare contractors can publish additional local billing and coverage guidance.

Using Multiple Discipline Modifiers

CMS contractor edits require the applicable discipline modifier and do not permit multiple GN/GO/GP modifiers on the same institutional service line.

Modifier GN Documentation Checklist

What billing and AR teams should verify.

Before Claim Submission

Patient Medicare coverage verified.
CPT/HCPCS code verified.
Code checked against applicable therapy requirements.
Speech-language pathology plan of care confirmed.
GN applied when required.
Other applicable modifiers reviewed.
Units and dates of service checked.
Claim setting verified.

After Denial

ERA/EOB reviewed.
CARC/RARC documented.
Modifier sequence verified.
Therapy code list checked.
SLP plan of care reviewed.
KX requirement reviewed when applicable.
MAC guidance checked.
Corrected claim or appeal decision documented.

Simplified Claim-Line Examples

Examples are for understanding modifier relationships, not payment-rate calculation.

Scenario	Therapy Discipline	Example Modifier	Why
Outpatient SLP service under SLP plan of care	Speech-Language Pathology	GN	Identifies the SLP plan of care.
Outpatient PT service under PT plan of care	Physical Therapy	GP	Identifies the PT plan of care.
Outpatient OT service under OT plan of care	Occupational Therapy	GO	Identifies the OT plan of care.
Applicable SLP service above therapy threshold	Speech-Language Pathology	GN + KX	Only when the separate KX requirements are met.

Billing Reminder

GN and KX serve different purposes. The presence of GN does not automatically mean KX is required. Verify the current Medicare therapy threshold and medical-necessity requirements for the specific claim.

2026 Medicare SLP Points

Current-year information useful for billing and AR teams.

2026

SLP KX Threshold

For CY 2026, CMS lists a $2,480 KX modifier threshold amount for physical therapy and speech-language pathology services combined.

SLP Discipline

GN identifies applicable services delivered under an outpatient speech-language pathology plan of care.

CMS

2026 Therapy List

CMS maintains a 2026 Therapy Code List and Dispositions identifying codes that sometimes or always describe therapy services.

Important: GN itself does not establish medical necessity, guarantee payment or replace documentation requirements. The complete Medicare speech-language pathology requirements must be met.

Modifier GN + KX: Do Not Confuse Them

Two modifiers can appear in the same therapy claim but perform very different functions.

What GN Identifies

GN identifies the applicable service as being delivered under an outpatient speech-language pathology plan of care.

GN = SLP plan of care

What KX Addresses

KX is associated with Medicare therapy-threshold requirements and indicates that the applicable documentation and medical-necessity requirements have been met.

KX = applicable therapy threshold requirements

GN and KX are not interchangeable.
GN identifies the SLP plan of care; KX addresses separate therapy-threshold requirements.

How to Prevent GN Denials

Build modifier accuracy into the front-end billing workflow.

Verify Discipline

Confirm that the service is being delivered under an SLP plan of care.

Verify Code

Check the current Medicare therapy code list.

Audit Modifiers

Check GN, KX and other applicable modifiers before transmission.

Train AR

Teach AR callers to separate modifier errors from medical-necessity and documentation denials.

Modifier GN Quick Cheat Sheet

A fast reference for medical billing and AR teams.

    
        GN = Services delivered under an outpatient
        speech-language pathology plan of care.
      
        GO = Occupational therapy plan of care.
      
        GP = Physical therapy plan of care.
      
        GN is a discipline-specific therapy modifier.
      
        Do not use GN with codes that are not on the applicable
        therapy services list.
      
        Do not use GN to turn a non-therapy service into an SLP
        therapy service.
      
        GN does not automatically mean KX is required.
      
        For CY 2026, CMS lists $2,480 as the combined PT and SLP
        KX threshold.
      
        Verify the SLP plan of care.
      
        Check the current CMS therapy code list.
      
        Review CMS and MAC guidance for unusual cases.
      
        Always investigate the actual CARC/RARC before rebilling.

Official Medicare References

Primary sources for verifying current Modifier GN requirements.

CMS Medicare Claims Processing Manual — Chapter 5 CMS defines GN as the modifier for services delivered under an outpatient speech-language pathology plan of care and explains the discipline-specific therapy modifier requirements.

CMS Therapy Services — CY 2026 CMS’s current therapy-services resource includes the CY 2026 therapy code list, current therapy-threshold information and other Medicare therapy billing updates.

CMS Annual Therapy Update CMS publishes the annual Therapy Code List and Dispositions, identifying codes that sometimes or always describe therapy services.

CMS Speech-Language Pathology Billing Guidance CMS Medicare Coverage Database articles provide speech-language pathology-specific billing and coding guidance and refer providers to the Medicare Claims Processing Manual for the GN requirement.

Educational Disclaimer

This page is intended for US medical billing, coding and Revenue Cycle Management education. Modifier requirements can depend on the exact CPT/HCPCS code, claim type, provider setting, date of service and Medicare policy. Always verify current CMS and MAC guidance before billing, correcting or appealing a claim.

Modifier GN FAQs

Common questions from medical billers, coders and AR callers.

What does Modifier GN mean?

Modifier GN means services delivered under an outpatient speech-language pathology plan of care.

Is GN a speech-language pathology modifier?

Yes. GN is the Medicare discipline-specific modifier used for applicable speech-language pathology services delivered under an outpatient SLP plan of care.

What is the difference between GN and GO?

GN identifies speech-language pathology. GO identifies occupational therapy. They represent different therapy disciplines and are not interchangeable.

What is the difference between GN and GP?

GN identifies speech-language pathology. GP identifies physical therapy.

Is GN required on every speech therapy claim?

Medicare requires the applicable discipline-specific therapy modifier for applicable therapy services. However, the exact requirement depends on the service and current Medicare therapy rules. Verify the current therapy code list.

Can GN be used with any CPT code?

No. CMS states that GN, GO and GP should not be used with codes that are not on the applicable therapy services list.

Does GN mean an SLP personally performed the service?

CMS describes GN as identifying services delivered under an outpatient speech-language pathology plan of care. The modifier should not be interpreted as a blanket statement that every service was personally performed by the SLP.

Can GN be used for physical therapy?

No. Physical therapy services use GP when the applicable Medicare therapy modifier is required.

Can GN be used for occupational therapy?

No. Occupational therapy services use GO when the applicable Medicare therapy modifier is required.

Does GN guarantee Medicare payment?

No. GN identifies the applicable SLP discipline. It does not by itself establish medical necessity, coverage or payment.

What should an AR caller check for a GN denial?

Review the ERA/EOB, CARC, RARC, CPT/HCPCS code, GN modifier, therapy code status, SLP plan of care, documentation, claim setting and any applicable KX requirement.

What is the 2026 Medicare SLP KX threshold?

CMS lists $2,480 for CY 2026 for physical therapy and speech-language pathology services combined. KX is separate from GN and should only be reported when its applicable Medicare requirements are satisfied.

Where can I verify current GN requirements?

Start with the current CMS Medicare Claims Processing Manual Chapter 5, the CMS Therapy Services resources, the annual therapy code list and the applicable Medicare Administrative Contractor guidance.

Can multiple GN, GO and GP modifiers be reported on one line?

CMS contractor edits for institutional claims require the applicable discipline modifier and do not permit more than one GN, GO or GP modifier on the same service line.

What happens if the wrong therapy modifier is billed?

The claim may be rejected, returned or denied depending on the claim type and applicable Medicare edits. The billing team should identify the actual root cause, verify CMS/MAC requirements and submit a corrected claim or appeal when appropriate.

Master Medicare Therapy Modifiers

Continue learning GN, GO, GP, KX, CO, CQ, 25, 59, GY, GZ and other practical modifiers used in US medical billing and Revenue Cycle Management.

Explore LearnMedicalBilling.in