 The lower the tier, the lower the co-pay.For example, Tier 1 might include all of the Plan's preferred generic drugs, and each drug within this tier might have a co-pay of $5 to $10 per prescription.Tier 2 might include the Plan's preferred brand drugs with a co-pay of $40 to $50, while Tier 3 may be reserved for non-preferred brand drugs which are covered by the plan at a higher co-pay, perhaps $70 to $100.