Medicare screening services are limited to a specific frequency (e.g., once every 2 years, once every year). A physician may not know whether a patient is eligible for this service in a given year. If she is not eligible, the service will be denied. Therefore, the physician should ask the patient to sign an advance beneficiary notice of noncoverage (ABN) using the form provided by Medicare.

Claims for Medicare patients should be submitted with the appropriate HCPCS modifier.

GA modifier indicates that an ABN form has been signed.
GZ modifier indicates that an ABN form has not been signed. (Item or service expected to be denied as not reasonable and necessary)
GY modifier indicates that the service provided is not a covered Medicare benefit. The service is being reported to Medicare in order to receive a denial.

Using the appropriate modifier ensures that the patient will receive the correct information on her Explanation of Benefits (EOB). For example, when a service is reported with a GY modifier, the EOB will state that it is not covered and therefore is the patient’s responsibility.