Provides that, for individual health insurance coverage, the defined cost sharing for a prescription drug be calculated at the point of sale and based on a price that is reduced by an amount equal to at least 85% of all rebates received by the insurer in connection with the dispensing or administration of the prescription drug. Requires that, for group health insurance coverage, an insurer: (1) pass through to a plan sponsor 100% of all rebates received or estimated to be received by the insurer concerning the dispensing or administration of prescription drugs to the covered individuals of the plan sponsor; (2) provide a plan sponsor, at the time of contracting, the option of calculating defined cost sharing for covered individuals of the plan sponsor at the point of sale based on a price that is reduced by some or all of the rebates received or estimated to be received by the insurer concerning the dispensing or administration of the prescription drug; and (3) disclose specified information to the plan sponsor. Allows the department of insurance to enforce the provisions and impose a civil penalty.