Medicare Modifiers

Browse Medicare modifiers used for coverage determinations, compliance requirements, and payer-specific billing scenarios.

A Modifiers

AT

Active Chiropractic Treatment

Identifies active chiropractic treatment for qualifying acute or chronic subluxations

AV

Prosthetic or Orthotic Item

Identifies items furnished with qualifying prosthetic devices, prosthetics, or orthotics

AW

Surgical Dressing Item

Identifies eligible items used with surgical dressings.

AX

Dialysis-Related Item

Identifies eligible items used with dialysis services.

AY

Non-ESRD Item or Service

Identifies services unrelated to an ESRD patient's treatment

AB

Direct Access Audiology

Identifies qualifying audiology services furnished without physician orders

AC

ACCESS Model Participant

Identifies qualifying services furnished through Medicare's ACCESS Model

AE

Registered Dietitian Services

Identifies services furnished by registered dietitians or nutrition professionals

AG

Identifies professional services furnished by a primary physician.

Primary Physician

AK

Nonparticipating Physician

Identifies services furnished by Medicare nonparticipating physicians

AO

Physician Team Member

Alternate Payment Declined

Identifies applicable alternate payment method election circumstances

Identifies physician services furnished as a team member

AQ

Refractive State Not Determined

Identifies eye services performed without refractive-state determination

Identifies physician services in qualifying unlisted HPSA locations

Unlisted HPSA

AR

Identifies services under the former physician scarcity program

Physician Scarcity Area

G Medicare Modifiers

GA

Waiver of Liability Statement on File

Required waiver is on file for an expected denial

GX

Notice of Liability Issued

A voluntary notice of liability was issued for a non-covered service.

GY

Item or Service Statutorily Excluded

Used when an item or service is statutorily excluded from Medicare coverage

GZ

Item or Service Expected to Be Denied as Not Necessary

Used when a provider expects Medicare to deny a service because it is not considered reasonable

GQ

Telehealth services provided through an asynchronous telecommunications

Via Asynchronous Telecommunications System

GG

Identifies screening converted to diagnostic mammography

Screening Mammogram Converted to Diagnostic

GC

Resident Service Under Teaching Physician

Identifies resident services directed by a teaching physician

GE

Resident Service Under Primary Care Exception

Identifies resident services under the primary care exception.

GB

Waiver of Liability Statement on File

Identifies eligible nonphysician practitioner services in a CAH

GF

Nonphysician Practitioner Service in a CAH

Identifies eligible nonphysician practitioner services in a CAH

GJ

Opt-Out Practitioner Emergency or Urgent Service

Identifies opt-out practitioner emergency or urgent services

GK

Necessary Service With GA or GZ

Identifies necessary services associated with GA or GZ

K Medicare Modifiers

KX

Medical Policy Requirements Met

Indicates medical policy requirements and documentation are met

KZ

Identifies services subject to specific Medicare implementation guidance

New Coverage Pending MAC Implementation

Q Medicare Modifiers

QW

CLIA Waived Test

Identifies laboratory tests meeting CLIA-waived requirements

Q6

Fee-for-Time Substitute Services

Identifies substitute physician services under fee-for-time arrangements

Q6

Reciprocal Billing Arrangement

Identifies substitute physician services through reciprocal billing

About Medicare Modifiers

Medicare modifiers provide additional information about services, procedures, supplies, and billing circumstances reported on Medicare claims. They are reported with CPT or HCPCS codes when additional information is necessary to accurately describe how an item or service was furnished.

CMS explains that modifiers may function as pricing indicators or informational and tracking indicators for Medicare. Depending on the modifier, it may affect payment, communicate coverage circumstances, identify a provider's role, or supply information Medicare needs to process the claim correctly.

Medicare modifier requirements vary considerably. Some apply to Advance Beneficiary Notice situations, others indicate that medical policy requirements have been met, and still others identify specific practitioners, geographic circumstances, or services.

The underlying CPT or HCPCS code should always accurately represent the service before a modifier is selected. For additional procedure-code information, billing examples, and documentation guidance, visit CPTCodeGuide.com.

Common Uses of Medicare Modifiers

Coverage Information: Certain modifiers communicate whether a service is expected to be covered or denied under Medicare requirements.

Beneficiary Liability: Modifiers such as GA, GX, GY, and GZ can provide important information about noncovered services, Advance Beneficiary Notices, and potential financial responsibility.

Medical Policy Requirements: Some modifiers indicate that specified Medicare coverage or medical policy requirements have been satisfied.

Provider Identification: Medicare uses certain modifiers to identify the type or role of the physician or qualified healthcare professional furnishing a service.

Geographic Requirements: Some modifiers provide information about services furnished in qualifying geographic areas, including certain Health Professional Shortage Area circumstances.

Claim Processing: Modifiers can provide information Medicare needs to correctly price, review, or otherwise process a reported service.

Billing and Documentation Considerations

Medicare modifiers should only be reported when the circumstances represented by the modifier actually apply to the service. The medical record and other required supporting information should substantiate the modifier when documentation is necessary.

Providers should also verify that the modifier is appropriate for the specific CPT or HCPCS code. A valid Medicare modifier is not necessarily appropriate with every procedure code, service type, provider, or claim setting.

When multiple modifiers are necessary, order can also matter. For hospital outpatient claims, CMS instructs providers to report the most specific applicable modifiers first in certain situations. CMS-1500 professional claims can accommodate up to four modifiers with a HCPCS code.

Medicare modifier requirements can also change. Current CMS guidance, Medicare Administrative Contractor instructions, coverage policies, and applicable code updates should be reviewed rather than assuming that historical modifier instructions remain current.

Common Medicare Modifier Billing Mistakes

Using a Modifier Without Support: A modifier should accurately represent the documented circumstances of the service rather than being added simply to obtain payment.

Using the Wrong Liability Modifier: GA, GX, GY, and GZ communicate different coverage and beneficiary-notice circumstances and should not be treated as interchangeable.

Ignoring Code Compatibility: A modifier may be valid but inappropriate with the particular CPT or HCPCS code being reported.

Using Outdated Requirements: Medicare coding and payment policies change, making current CMS and MAC guidance important when determining modifier use.

Incorrect Modifier Order: When several modifiers apply, incorrect sequencing can affect how Medicare interprets or processes the claim.

Assuming a Modifier Guarantees Payment: Correct modifier reporting does not override medical necessity, coverage, provider eligibility, or other Medicare payment requirements.

Medicare Modifier Documentation Checklist

Before submitting a Medicare claim with a modifier, verify that the record and applicable claim information support:

The CPT or HCPCS code reported
The patient's diagnosis and reason for the service
Medical necessity when required
The specific circumstance represented by the modifier
The physician or practitioner who furnished the service
Applicable provider qualifications or roles
Required notices or beneficiary-liability information
Relevant dates, locations, units, and quantities
Any applicable Medicare coverage criteria
Required orders, certifications, or plans of care
The correct modifier combination and sequence
Current CMS or Medicare Administrative Contractor requirements

Documentation should support the service and explain the circumstance communicated by the modifier when that circumstance is not apparent from the procedure code itself.

Medicare Modifier Denials

Missing, incorrect, or unsupported modifiers can contribute to Medicare claim denials, rejections, or payment adjustments.

For example, CMS distinguishes between GA, GX, GY, and GZ based on why a service may not be covered and whether applicable beneficiary notice requirements have been addressed. Reporting the wrong modifier can therefore communicate substantially different information to Medicare.

Modifier-related problems may also involve incorrect code combinations, medical necessity, missing documentation, provider eligibility, or services that do not satisfy applicable Medicare coverage policies.

When a Medicare claim is denied, the modifier should not automatically be changed simply to obtain payment. Review the procedure code, modifier, documentation, Medicare policy, and denial reason before submitting a corrected claim or appeal.

For explanations of common claim adjustment and denial codes, visit DenialCodeLookup.com.

Medicare Modifiers and NCCI Edits

Medicare's National Correct Coding Initiative uses coding edits to help prevent improper reporting of services that should not ordinarily be billed together.

Certain modifiers may be appropriate when documentation establishes that services are legitimately distinct. CMS specifically provides guidance for Modifier 59 and the XE, XP, XS, and XU modifiers in connection with NCCI coding.

A modifier should not be appended merely because an NCCI edit prevents payment. The clinical circumstances and documentation must support separate reporting under applicable Medicare requirements.

Understanding Medicare Modifier Types

Coverage and Liability Modifiers: Modifiers such as GA, GX, GY, and GZ communicate specific circumstances involving expected noncoverage, beneficiary notices, or liability.

Medical Policy Modifiers: Modifiers such as KX may communicate that specified coverage or medical policy requirements have been satisfied when applicable.

Provider and Practitioner Modifiers: Certain modifiers identify the physician, practitioner type, or professional role associated with a service.

Geographic Modifiers: Modifiers such as AQ may be used under specific Medicare rules involving qualifying Health Professional Shortage Areas.

Distinct Service Modifiers: Modifier 59 and the XE, XP, XS, and XU modifiers can communicate distinct circumstances when Medicare's requirements for separate reporting are satisfied.

Service-Specific Modifiers: Some Medicare modifiers apply only to particular services, supplies, payment systems, or coverage policies.

Frequently Asked Questions

Are Medicare modifiers required on every Medicare claim?
No. A modifier should be reported when it is necessary to accurately describe the service or when Medicare billing requirements specifically require it. Many services can be correctly submitted without a modifier.

Can more than one Medicare modifier be reported with the same code?
Yes. Multiple modifiers may be appropriate when separate circumstances apply to the same service. Each modifier should be valid for the code and supported by applicable documentation and Medicare requirements.

Does adding a Medicare modifier guarantee payment?
No. A modifier provides additional claim information but does not independently establish coverage or medical necessity. Medicare payment remains subject to applicable benefit, coding, documentation, provider, and payment requirements.

Medicare Billing Resources

CMS maintains the Medicare Claims Processing Manual, NCCI guidance, HCPCS information, coverage policies, and other resources used to determine appropriate claim reporting. The Medicare Claims Processing Manual contains detailed instructions covering different provider types and services.

When researching a claim, start with the underlying CPT or HCPCS code, determine whether a Medicare modifier is required, verify that the documentation supports it, and then review applicable Medicare or MAC requirements before submission.