When traveling to a CBA, the beneficiary can choose to either:

- Receive oxygen and rent oxygen equipment from a contract supplier in the traveling CBA, or
- Continue to receive oxygen and rent oxygen equipment from the grandfathered supplier.

Upon returning to the home CBA, the beneficiary may return to the grandfathered supplier or start renting equipment or services from a contract supplier.

Suppliers of oxygen and oxygen equipment (which includes grandfathered suppliers) must directly furnish, or subcontract with a non-billing supplier to furnish, oxygen and oxygen equipment to the beneficiary for the entirety of each month it receives payment (i.e., up to the next anniversary date for the beneficiary's oxygen and oxygen equipment). For subsequent rental months that the beneficiary is outside the service area, the home supplier must either provide the equipment and related items/services or assist the beneficiary in finding another supplier in the new location. The home supplier may not bill for or be reimbursed by Medicare if it is not providing oxygen equipment or has not made arrangements with a different supplier to provide the equipment on the anniversary billing date. Medicare will pay only one supplier to provide oxygen during any one rental month.

Note: The grandfathering requirement described above applies to other competitively bid rental items with one exception: The supplier that furnishes the oxygen or oxygen equipment in the 36th month of continuous use is prohibited from transferring its ongoing obligations to a contract supplier, regardless of whether it has elected to become a grandfathered supplier and regardless of whether the beneficiary remains in the CBA.