Effective for dates of service on or after April 13, 2026, Medicare requires that certain oxygen equipment HCPCS codes (E0424, E0431, E0433, E0434, E0439, E1390, E1391, and E1392) require both a face-to-face (F2F) encounter and a Written Order Prior to Delivery (WOPD) as conditions of Medicare payment. The F2F visit must occur within six months prior to the order, and the completed written order must be in place before the equipment is delivered—otherwise, the claim may be denied.