The Authority may recover the amount of any increased premium resulting from an adjustment under section 473 only if the premium relates to one or more of the following—
(a) the premium period to which the notice under section 473 relates;
(b) any of the 4 premium periods immediately before that period;
(c) any other premium period if the Authority reasonably believes that there is, or was, fraud on the part of the employer or of any person acting, or apparently acting, on the employer's behalf in relation to the calculation or payment of the premium.