The commissioner may delay the repayment requirement for recipients enrolled on at least a half-time basis at an eligible institution. These deferment periods are not included when calculating the maximum repayment period. The commissioner may also waive or delay repayment for recipients who give evidence of extreme financial hardship, in which case the period of postponement will be included in determining the maximum repayment periods. The board may require payments on the interest being accrued during the time of a postponement.