(A) Calculation of household income on a prospective basis is the calculation of income on the basis of the income reasonably anticipated to be received by the household during the period for which eligibility or benefits are being determined. Such calculation shall be made in accordance with regulations prescribed by the Secretary which shall provide for taking into account both the income reasonably anticipated to be received by the household during the period for which eligibility or benefits are being determined and the income received by the household during the preceding thirty days.

(B) Calculation of household income on a retrospective basis is the calculation of income for the period for which eligibility or benefits are being determined on the basis of income received in a previous period. Such calculation shall be made in accordance with regulations prescribed by the Secretary which may provide for the determination of eligibility on a prospective basis in some or all cases in which benefits are calculated under this paragraph. Such regulations shall provide for supplementing the initial allotments of newly applying households in those cases in which the determination of income under this paragraph causes serious hardship.