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Correct Billing Instructions for Modifiers GA, GX, GY and GZ


CMS allows Medicare Advantage (MA) plans to create billing and payment rules that are different from Original Medicare rules. For further information, go to Section 10.2, Chapter 4 of the Medicare Managed Care Manual.


In order for HMSA to know if contracting providers have given proper notice of non-coverage to our Medicare Advantage plan members, providers must follow our billing rules and use the modifiers as follows.


GA - Pre-service notice of non-coverage was provided by the plan.


Use this modifier to tell us that:


The claim will go to patient liability and you may bill the member.


If you bill us for non-covered services without using the GA modifier, HMSA will deny your claim. It will go to provider liability.


GZ - Service is not covered by Medicare.


The GZ modifier identifies that 1) an item or service is expected to be denied as not reasonable and necessary, and 2) no advance notice of non-coverage was supplied to the member.


If you bill us for services using the GZ modifier, the claim will go to provider liability and you may not bill the member.


Unless the service is clearly excluded in a member's EOC or other related materials, providers must request a pre-service organization determination if they know or have reason to know that a service they are rendering or referring may not be covered.

The GX and GY modifiers no longer need to be included on claims for non-covered services.


HMSA QUEST Integration

The GY modifier is recognized by QUEST Integration plans, however, providers should follow the HMSA QUEST Integration correct billing instructions for this modifier, refer to QUEST Integration - Third Party Liability - Coordination of Benefits - QUEST Integration and Medicare.



[i] A copy of the signed Agreement of Financial Responsibility must be submitted with the service in addition to modifier GA.



To see the previous version of this page, see CMS Requirement for Modifier Use.

First Published:07/11/2016
Latest Revision:03/19/2018
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