New Prosthetic Billing Modifiers

What You Need to Know

Prior to September 1, 2024, Medicare required the following modifiers on all prosthetic claims:

• LT or RT
• K0, K1, K2, K3, or K4 (K-level specific HCPCS codes only)

To facilitate claims processing and assist in the prevention of improper payments, Medicare now requires the addition of a third modifier on every prosthetic claim line:

• KX - Requirements specified in the medical policy have been met
• GA - Waiver of Liability statement (ABN) issued as required by payer policy
• GY - Item or service statutorily excluded or does not meet the definition of any Medicare benefit
• GZ - Item or service expected to be denied as not reasonable or necessary

 All prosthetic HCPCS codes submitted to the DME MACs with date of service on or after September 1, 2024 must be billed with a KX, GA, GY, or GZ modifier in the first position. Any claim lines billed without one of these modifiers will be rejected as missing information. Conversely, if more than one of these four modifiers is used on the same claim line together, the claim will deny as unprocessable. In both situations, the claim would need to be corrected and rebilled to Medicare.

What this Means for You

While the KX, GA, GY, and GZ modifiers are already required for lower limb orthotic claims (including AFOs, KAFOs, and knee braces), this protocol is new for lower limb prosthetic claims. Therefore, it is important to educate your billing staff on these new modifier requirements to help prevent claim processing delays and denials. Before billing a lower extremity prosthesis to Medicare, providers need to review the patient's medical records, including the physician's notes and prosthetist's notes. If the LCD coverage criteria are met and documented for all codes, then bill with the KX modifier on each claim line followed by the LT/RT modifier and K-level modifier, if applicable. If you expect a medical necessity denial for any of the codes, then it is not appropriate to use the KX modifier. Instead, bill that individual claim line with either the GA modifier (if you have a properly executed ABN on file) or the GZ modifier (without an ABN on file). Items submitted with the GZ modifier are automatically denied and not subject to complex medical review. Lastly, if the billed code is not a covered Medicare benefit, such as donning sleeves (L7600) or an adjustable heel height feature (L5990), use the GY modifier instead of KX. 

For more information, review the Modifiers section of the Lower Limb Prostheses Policy Article and Noridian's article on Modifiers.