How to Bill with GY, GA, and GZ Modifiers: Complete Guide to Medicare Modifier Usage

How to Bill with GY, GA, and GZ Modifiers

In medical billing, modifiers clarify the details of a service and influence how a claim is processed. Among them, the GY modifier holds a specific role: it tells Medicare that a service is statutorily excluded—in other words, not covered by Medicare under any circumstances. This helps ensure correct denial handling and clarifies that the patient—not Medicare—is responsible for the full cost.

Let’s explore what the GY modifier in medical billing really means, when to use it, how to apply it, and how it fits into a clean and compliant billing and coding strategy.

What Is the GY Modifier in the Medicare Program?

The GY modifier is a two-character HCPCS modifier appended to CPT or HCPCS codes to indicate that the item or service is statutorily excluded. It does not qualify as a Medicare benefit because Medicare does not pay for it under any condition.

When a provider adds the modifier to a CPT code, they intentionally notify Medicare that the medical service should be automatically denied. This gives the provider the ability to bill the patient or submit the claim to secondary insurance.

📌 Modifier indicates: “This is not a Medicare benefit, and Medicare will deny the claim.”

This is different from services denied for lack of medical necessity, which require the GZ modifier.

When to Use the GY Modifier

Use the GY modifier when a medical service is excluded by statute—not just due to necessity or coding. Common examples include:

  • Routine eye exams

  • Cosmetic procedures

  • Personal comfort items

  • Dental cleanings

  • Services provided outside the U.S.

These are Medicare benefits that are never covered. So, you use this modifier to communicate clear exclusion. Medicare will automatically reject claims with GY, making it easier to bill the patient or secondary insurer.

Comparing GY and GZ Modifiers

Modifier When to Use ABN Required
GY Service is statutorily excluded ❌ No
GZ Service lacks medical necessity and ABN was not issued ✅ Yes (if applicable)

While GY and GZ may seem similar, they are not interchangeable. Modifier GZ is used when medical necessity is in question, and GY is used when Medicare doesn’t cover the service at all.

Understanding GA Modifier and ABN Use

The GA modifier is used when an ABN was issued for services that Medicare might deny due to lack of medical necessity. In contrast to GY, use the GA modifier only when an Advance Beneficiary Notice (ABN) is signed.

When a voluntary ABN was issued, the GX modifier is appropriate instead. If you append modifier GA on the claim, it tells Medicare to process it with potential denial logic.

Use GA if you’ve prepared for a likely denial but have documented the patient’s awareness. Medicare will still deny the claim, but your practice is protected.

Step-by-Step: How to Use the GY Modifier

  1. Identify that the item or service is excluded and not covered by Medicare.

  2. Add the GY modifier to the CPT or HCPCS code.

  3. Do NOT issue an ABN—it’s not required for statutorily excluded services.

  4. Submit the claim.

  5. Once denied, bill the patient or file to a secondary payer.

Using the correct modifiers reduces confusion and improves payment turnaround. Without the GY, your claim would be without GY logic and potentially delayed.

Billing and Documentation Guidelines

  • Document that the item or service is excluded by law.

  • Make it clear that the patient is not responsible until Medicare denies the claim.

  • If ABN was issued in error, correct the claim with the appropriate modifier to a corrected claim.

  • Use modifiers while billing Medicare only if applicable.

CMS created two modifiers that allow proper denial flow: GA (with ABN) and GY (no ABN, statutory exclusion). These can be combined with modifiers like GX or TS in certain scenarios.

Services Commonly Submitted with GY

Service Reason for GY
Eye exam (92014) Routine exam; Medicare does not cover
Liposuction (15877) Cosmetic procedure
TV rental (A9270) Personal comfort item
Dental cleaning (D1110) Otherwise not a Medicare benefit
International treatment Medicare does not cover services outside the U.S.

These examples show when the GY modifier is used—not for questionable coverage, but for services that do not meet the definition of Medicare.

Compliance Strategy: Using GY, GA, and GZ Correctly

  • Use a GA modifier when you have a signed ABN and anticipate a denial.

  • Use the GZ modifier when you believe Medicare may deny but have no ABN.

  • Use the GY modifier when the item or service is simply not a Medicare benefit.

By understanding the correct use of modifiers, practices can:

  • Avoid audits

  • Bill Medicare correctly

  • Bill the patient confidently

  • Trigger reimbursement by Medicare where secondary insurance applies

Even though the modifier is present, it doesn’t guarantee payment—it only sets the logic for rejection or approval.

FAQs

Is the patient responsible when GY is used?

Yes, Medicare will automatically deny, and the provider can bill the patient.

Should I use GA or GY?

If the service is statutorily excluded, use GY. If it’s potentially denied for medical necessity, use the GA modifier.

Can I bill both GA and GZ together?

No. Two modifiers like GA modifier and modifier GZ should never appear on the same line.

Can GY be used for covered services?

No. Modifier applied to any covered service by mistake will result in incorrect processing.

Does Medicare ever pay when GY is used?

No. Medicare will not pay for services submitted with a GY modifier, but the denial can be used to bill secondary or the patient if not covered.

Conclusion: Mastering the Use of Modifiers in Medicare Claims

Understanding modifier GY, modifier GA, and modifier GZ is critical for modern medical billing and coding teams. These codes define financial responsibility, streamline denial handling, and ensure compliance with Medicare Part B policy.

Whether your goal is to document a non-covered service, issue an ABN, or use this modifier to trigger proper denial logic, accuracy matters.

If your team needs support applying these codes correctly, our team is here to help.

Work with a Medical Billing Company That Gets It Right

At Swift Medical Billing, we help providers bill Medicare, apply modifiers properly, and optimize denial workflows.

Let us show you how to use the modifier GY and other Medicare modifiers GA, GZ, and GX in a way that keeps your cash flow strong and your claims compliant.

Schedule your consultation now and simplify your revenue cycle.