; (B) fully disclosed and enumerated to the group health plan sponsor, as described in paragraphs (1) and (4) of subsection (b); (C) available for audit by the plan sponsor, or a third-party designated by a plan sponsor not less than once per plan year; and (D) returned to the issuer or entity providing pharmaceutical benefit management services by the group health plan if audits by such issuer or entity indicate that the amounts received are incorrect after such amounts have been paid to the group health plan. (3) Audit of rebate contracts A third-party administrator of a group health plan, a health insurance issuer offering group health insurance coverage, or an entity providing pharmacy benefit management services under such health plan or health insurance coverage shall make rebate contracts with rebate aggregators or drug manufacturers available for audit by such plan sponsor or designated third-party, subject to confidentiality agreements to prevent re-disclosure of such contracts. (4) Auditors The applicable plan sponsor may select an auditor for purposes of carrying out audits under paragraphs (2)(C) and (3). (5) Rule of construction Nothing in this subsection shall be construed to prohibit payments to entities offering pharmacy benefit management services for bona fide services using a fee structure not contemplated by this subsection, provided that such fees are transparent to group health plans and health insurance issuers. (e) Enforcement (1) In general The Secretary, in consultation with the Secretary of Health and Human Services and the Secretary of the Treasury, shall enforce this section. (2) Failure to provide timely information A health insurance issuer or an entity providing pharmacy benefit management services that violates subsection (a) or fails to provide information required under subsection (b); a group health plan, health insurance issuer, or entity providing pharmacy benefit management services that violates subsection (c)