((a)) The Administrator, on such terms and conditions as he may from time to time prescribe, shall make periodic payments to the pool formed or otherwise created under , in recognition of such reductions in chargeable premium rates under below estimated premium rates under as are required in order to make flood insurance available on reasonable terms and conditions.
((b)) Designated periods under this section and the methods for determining the sum of premiums paid or payable during such periods shall be established by the Administrator.