CGS Administrators, the Jurisdictions B and C DME MAC, has issued guidance on nebulizer claims rejected because of missing modifiers.
In a March 11 bulletin, CGS said, “For dates of service on or after Feb. 1, 2026, suppliers must add one of the KX, GA or GZ modifiers to claims for all nebulizers, nebulizer-related drugs, nebulizer-related supplies [and] nebulizer dispensing fees.”
In one common scenario, CGS said, suppliers’ claims are missing the KX, GA or GZ modifier “on any drugs, dispensing fees, supplies, etc. The entire claim was rejected with ANSI Reason Code CO-4.” Those rejected claims can be submitted with the appropriate modifier included.
If suppliers billed the KX, GA or GZ modifier “on the drug and suppliers, but not on the dispensing fee,” CGS said it “split the claim, rejected the dispensing fee with CO-4, and processed the rest of the claim correctly.”
In those cases, suppliers can submit a written reopening request using the myCGS web portal, or they can mail or fax a Medicare reopening request form.
