; and (II) apply a cost-sharing requirement with respect to each cost-sharing tier described in subclause (I) on the formulary that is meaningfully lesser than the lowest cost-sharing requirement applicable with respect to any cost-sharing tier on such formulary that includes a brand drug (referred to in this subparagraph as the lowest brand drug cost-sharing tier ). (ii) Specialty generic drug cost-Sharing tier With respect to a plan year beginning on or after January 1, 2021, if the PDP sponsor offering the prescription drug plan has a cost-sharing tier for specialty brand drugs on the formulary, the PDP sponsor shall— (I) have a cost-sharing tier on such formulary that only includes covered generic drugs and covered biosimilar biological products— (aa) for which the wholesale acquisition cost is greater than a threshold specified by the Secretary; and (bb) with respect to which the reference drug for such a covered generic drug or the reference biological product for such a covered 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