In Medicare coding, what does the GY modifier indicate?

• A. That the treatment is not covered by Medicare
• B. Requires prior authorization
• C. Indicates a service is preventive
• D. Indicates patient liability before payment

Answer: (A)

The GY modifier signals that the item or service is not covered by Medicare. It indicates a statutorily non-covered service, so Medicare will not reimburse the claim. Because Medicare won’t pay, the provider may bill the patient for the service according to their policy. This is different from requiring prior authorization, indicating a preventive service, or showing patient liability by itself. The key idea is that the service is not payable by Medicare under the rules, hence no Medicare payment.