; and (II) with respect to each cost-sharing tier described in subclause (I) on the formulary, either apply no cost-sharing requirement or a copayment that is— (aa) in the case where the lowest branded drug tier of such formulary bases cost-sharing on a copayment amount, an amount at least $20 lower than the copayment for such lowest branded drug tier (but in no case may such copayment amount be less than zero); or (bb) in the case where the lowest branded drug tier of such formulary bases cost-sharing on a coinsurance percentage, an amount at least $20 lower than the actuarially expected average cost-sharing amount payable for the covered part D drugs included on such lowest branded drug tier, determined using processes and methods established under section 1860D–11(c) (but in no case may such copayment amount be less than zero). (ii) Specialty generic drug and biosimilar biological product cost-sharing tier With respect to a plan year beginning on or after January 1, 2025, if the PDP sponsor offering the prescription drug plan has a specialty tier, the PDP sponsor shall— (I) have a second specialty tier on such formulary that only includes part D generic drugs and part D biosimilar biological products— (aa) for which the cost (as defined by the Secretary) is greater than a cost threshold specified by the Secretary; and (bb) with respect to which the part D reference drug for such a part D generic drug or the part D reference biological product for such a part D biosimilar biological product is either included on a cost-sharing tier on such formulary with a cost-sharing requirement that is greater than the cost-sharing requirement applied under subclause (II), or excluded from such formulary