; and (ii) 1 percent in the case of each subsequent plan year. (C) Determinations by actuaries Determinations as to increases in actual costs under a plan (or coverage) for purposes of this section shall be made and certified by a qualified and licensed actuary who is a member in good standing of the American Academy of Actuaries. All such determinations shall be in a written report prepared by the actuary. The report, and all underlying documentation relied upon by the actuary, shall be maintained by the group health plan or health insurance issuer for a period of 6 years following the notification made under subparagraph (E). (D) 6-month determinations If a group health plan (or a health insurance issuer offering coverage in connection with a group health plan) seeks an exemption under this paragraph, determinations under subparagraph (A) shall be made after such plan (or coverage) has complied with this section for the first 6 months of the plan year involved. (E) Notification (i) In general A group health plan (or a health insurance issuer offering coverage in connection with a group health plan) that, based upon a certification described under subparagraph (C), qualifies for an exemption under this paragraph, and elects to implement the exemption, shall promptly notify the Secretary, the appropriate State agencies, and participants and beneficiaries in the plan of such election. (ii) Requirement A notification to the Secretary under clause (i) shall include— (I) a description of the number of covered lives under the plan (or coverage) involved at the time of the notification, and as applicable, at the time of any prior election of the cost-exemption under this paragraph by such plan (or coverage); (II) for both the plan year upon which a cost exemption is sought and the year prior, a description of the actual total costs of coverage with respect to medical and surgical benefits and mental health and substance use disorder benefits under the plan