Part D Off-Label Prescription Parity Act - Amends part D (Voluntary Prescription Drug Benefit Program) of title XVIII (Medicare) of the Social Security Act to permit a prescription drug plan (PDP) sponsor offering a PDP or a MedicareAdvantage (MA) organization offering an MA-PD plan to offer coverage of covered part D drugs for uses that are determined to be for medically accepted indications based upon: (1) guidance provided by the Secretary of Health and Human Services (HHS) for determining accepted uses of covered part D drugs; and (2) supportive clinical evidence in peer reviewed medical literature.