Rural Ambulance Reimbursement Fairness Act This bill applies a higher payment rate for ambulance services under Medicare that are provided by certain critical access hospitals (CAHs) or CAH-owned entities in mountainous terrain or in areas with only secondary roads. Currently, the Centers for Medicare & Medicaid Services must pay 101% of the reasonable costs incurred for ambulance services provided by a CAH or by a CAH-owned entity if the CAH or entity is the only provider or supplier of ambulance services within a 35-mile drive of such CAH. The bill applies this payment rate to services provided by a CAH or entity that is the only provider or supplier of ambulance services within a 15-mile drive of such CAH in mountainous terrain or an area with only secondary roads.