56.—(1) The amount of repayments, if any, which is deducted by the employer must, subject to paragraph (2), be calculated by reference to the amount of earnings paid to, or provided to or for the benefit of, the borrower in respect of the employment, in the earnings period specified or determined in respect of those earnings for the purposes of the Contributions Regulations.
(2) Where earnings in respect of two or more employments—
(a)fall to be aggregated for the purposes of the Contributions Regulations; and
(b)the earnings periods in respect of those earnings are, by virtue of the Contributions Regulations, of different lengths,
the earnings period specified in respect of the aggregated earnings will be the shorter or shortest of those earnings periods.