Everything You Need to Know About ABN-Related Modifiers: GA, GX, GY, and GZ

Last month, WebPT hosted a webinar all about modifiers. During that presentation, compliance expert Tom Ambury and I discussed these sometimes confusing billing add-ons. And while yes, they are merely add-ons, they are anything but easy. So we can’t—and shouldn’t—brush them off. After all, they’re the tools we have to work with to tell our patients’ complete stories, demonstrate our value, and get paid for the services we provide—which is especially important in today’s environment of ever-declining payments.

During the webinar, we received quite a few questions—some really good ones and some pretty scary ones. For that reason, I thought it would be helpful to write a few modifier Q and A posts as a resource for the entire PT community.

Without further ado, here’s everything you need to know about the Advanced Beneficiary Notice of Noncoverage (ABN) modifiers: GA, GX, GY, and GZ. (Check back next month when I’ll cover the KX modifier and modifier 59.)

Q. What are GA, GX, GY, and GZ modifiers?

A.  GA, GX, GY, and GZ modifiers all relate to uncovered or non-medically necessary services. Here’s the low-down on each:

  • GA: Indicates that a required ABN is on file for a service or item not considered reasonable and medically necessary
    • Allows a provider to bill the patient or a secondary insurance if Medicare doesn’t cover services
    • Ensures Medicare will automatically assign liability to the beneficiary upon denial
    • Signals Medicare to use claim adjustment reason code 50 when denying lines containing the GA modifier (e.g., “These are noncovered services because this is not deemed a ‘medical necessity’ by the payer.”)
  • GX: Indicates a voluntary ABN was issued for non-covered services
    • Prompts automatic rejection from Medicare
    • If used on any line reporting covered charges, will prompt Medicare to return the claim
    • Can be combined with modifiers GY and TS (to indicate beneficiary liability) but not EY, GA, GL, GZ, KB, QL, or TQ
      • TS: Follow-up service
      • EY: No doctor’s order on file
      • GL: Medically unnecessary upgrade provided instead of non-upgraded item; no charge and no ABN
      • KB: Beneficiary requested upgrade for ABN; more than four modifiers identified on claim
      • QL: Patient pronounced dead after ambulance is called
      • TQ: Basic life support transport by a volunteer ambulance provider
  • GY: Indicates a non-covered service
    • Used when an ABN is not on file; patient is inherently liable for charges because it’s a non-covered service
    • GZ: Indicates that you expect the service to be denied because it isn’t medically necessary
    • Used when an ABN may be necessary but was not issued; patient is not responsible for payment

Q. What is the difference between a required ABN and a voluntary one?

A. According to CMS, “therapists are required to issue the ABN to original (fee-for-service) Medicare beneficiaries prior to providing therapy that is not medically reasonable and necessary regardless of the therapy cap.” However, “…when a provider/supplier provides a service that Medicare never covers, such as a service that fails to meet the definition of a Medicare benefit or a service that is explicitly excluded from coverage under §1862 of the Act, the limitation of liability protections in §1879 of the Act don’t apply. So, there is no requirement for suppliers/providers to alert beneficiaries to forthcoming financial liability prior to providing a never covered service. However, suppliers/providers may issue the ABN, Form CMS-R-131 as an optional notice to alert the beneficiary to liability.” Essentially, ABNs are required when the services in question may not be covered because they are not medically necessary; but they are not required—in other words, they are “voluntary”—when the services in question are never covered.

Q. What services does Medicare not cover?

A. Medicare will not cover therapy services if:

  • The therapist provides services for prevention, wellness, or fitness
  • The documentation or claim lacks something required, such as the plan of care
  • Medicare does not consider the services reasonable and medically necessary

Q. How do I know if the services I want to provide are medically necessary?

A. According to the APTA:

“Physical therapy, as part of an individual’s health care, is considered medically necessary as determined by the licensed physical therapist based on the results of a physical therapy evaluation and when provided for the purpose of preventing, minimizing, or eliminating impairments, activity limitations, or participation restrictions. Physical therapy is delivered throughout the episode of care by the physical therapist or under his or her direction and supervision; requires the knowledge, clinical judgment, and abilities of the therapist; takes into consideration the potential benefits and harms to the patient/client; and is not provided exclusively for the convenience of the patient/client. Physical therapy is provided using evidence of effectiveness and applicable physical therapy standards of practice and is considered medically necessary if the type, amount, and duration of services outlined in the plan of care increase the likelihood of meeting one or more of these stated goals: to improve function, minimize loss of function, or decrease risk of injury and disease.”

Q. Should I have all of my Medicare patients sign an ABN in case Medicare doesn’t pay?

A. Most definitely not. By having a patient sign an ABN, you are acknowleding that the services you are providing are either not medically necessary or not covered by Medicare—and that shouldn’t be the case for most of your patients. Besides, simply having an ABN on file does not give you permission to charge the patient for any unpaid claims, and too many ABNs can be a definite red flag for Medicare.

Now, if you obtain an ABN from a patient and include modifier GA or GX on your claim, then Medicare will know to deny the claim and assign financial responsibility to the patient. If you submit a claim to Medicare for non-medically necessary services without a modifier indicating that you and your patient are aware of the situation, Medicare will deny the claim and you may not go to the patient for payment.

In other words, it’s in your best interest to know the difference between covered and noncovered and medically necessary and unnecessary services—and to always document and bill appropriately.

Q. Do I really need to bill a non-covered charge to Medicare? Can’t I just collect payment directly from the patient?

You still need to bill Medicare for non-covered services. In this situation, you’d file a voluntary ABN with the patient, attach the appropriate G modifier to your claim. Then, once you receive a denial from Medicare, you can collect from the patient.


Have more ABN-related modifier questions? Send ’em my way in the comments section below, and I’ll respond with answers as soon as I can. Also, if you missed out on our webinar, you can watch a recorded version for free here.

About the Author

Heidi Jannenga, PT, MPT, ATC/L, Founder and COO of WebPT

As Chief Operating Officer, Heidi leads the product strategy and oversees the WebPT brand vision. She co-founded WebPT after recognizing the need for a more sophisticated industry-specific EMR platform and has guided the company through exponential growth, while garnering national recognition. Heidi brings with her more than 15 years of experience as a physical therapist and multi-clinic site director as well as a passion for healthcare innovation, entrepreneurship, and leadership.

An active member of the sports and private practice sections of the APTA, Heidi advocates for independent small businesses, speaks as a subject matter expert at industry conferences and events, and participates in local and national technology, entrepreneurship, and women-in-leadership seminars. Heidi is a mentor to physical therapy students and local entrepreneurs and leverages her platform to promote the importance of diversity, company culture, and overall business acumen for private practice physical therapy clinics.

Heidi was a collegiate basketball player at the University of California, Davis, and remains a life-long fan of the Aggies. She graduated with a BS in Biological Sciences and Exercise Physiology and went on to earn her MPT at the Institute of Physical Therapy in St. Augustine, Florida. When she’s not enjoying time with her daughter Ava, Heidi is perfecting her Spanish, practicing yoga, or hiking one of her favorite Phoenix trails.