GA Modifier – Definition and Example of How to Use

What is a Modifier?

A coding modifier is often used in medical billing. It adds extra information about the procedure code being used, without changing the definition of the code. 

If billing on a CMS-1500 form, medical modifiers go in box 24D, next to the CPT code. The form has spaces available for up to four modifiers.

CMS1500 form with box 24 highlighted with GA in the modifier section

GA Modifier Definition

The GA modifier is defined as, “waiver of liability statement issued, as required by payer policy.”

When to Use the GA Modifier

The GA modifier is to be used in certain situations when seeing a patient with Medicare. 

If Medicare does not cover a service, the Medicare beneficiary must fill out an Advance Beneficiary Notice (ABN), to be financially liable. This is done to protect the patient and help them make informed decisions. ABN forms can be obtained via the Center for Medicare & Medicaid Services (CMS) website.

When a claim will not be paid by Medicare because the procedure is seen as, “not reasonable and necessary,” the patient must fill out an ABN. If the claim is then sent to Medicare, the GA modifier should be added to indicate that the mandatory ABN was issued and is being kept on file. 

An example of a service that is “not reasonable and necessary” is when the service is continued beyond Medicare frequency limits. Another example would be when a service is covered by Medicare, but not for the reason or diagnosis the patient is getting the service for. 

When using the GA modifier, Medicare will deny the claim as patient responsibility, rather than provider responsibility. If an ABN is not issued and therefore the GA modifier is not used, the claim will be denied as provider responsibility. In this situation, collecting payment from the patient directly or from their secondary insurance will no longer be possible. 

Example of When and How to Use the GA Modifier

Medicare covers medical nutrition therapy by a dietitian for diabetes and chronic kidney disease for 3 hours for the first year and 2 hours for every subsequent year. 

If the patient’s situation meets the requirements to use procedure codes G0270 or G0271 in order to bill Medicare beyond this limit, Medicare will continue to pay for services as long as these specific codes are used. 

If the patient’s situation does not meet the criteria to use either G0270 or G0271, and the patient wants to continue medical nutrition therapy, this service is now considered to be, “not reasonable and necessary,” per Medicare’s frequency limit.

It is now the dietitian’s responsibility to have the patient sign an ABN and to collect payment from them. If the patient checks the box next to Option 1 on the ABN form, they are stating that they want Medicare to be billed. Payment can be collected upfront, but the provider must still send the claim to Medicare, per the patient’s request. Adding the GA modifier will ensure the claim is denied as patient responsibility, therefore payment will not need to be refunded to the patient.

If the patient has a secondary insurance that will pay for additional medical nutrition therapy appointments, Medicare needs to be billed first. Adding the GA modifier will deny the claim as patient responsibility so the secondary insurance can pay the claim. If the GA modifier is not added, the claim will be denied as provider responsibility and the secondary insurance will not pay the claim.

Other ABN Claim Reporting Modifiers


CPT 2021 Professional Edition

What are medical coding modifiers

Medicare Advance Written Notices of Non-Coverage

Memorandum Report: Medicare Payments for Part B Claim with G Modifiers

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