52.1. Where an operator sustains an annual loss in a fiscal year, the duties payable for a previous fiscal year in respect of which a claim was directly or indirectly filed under section 43.2 are deemed, for the purposes of computing the interest payable under sections 50 and 51, to be equal to the duties the operator would have had to pay if no claim had been directly or indirectly filed under section 43.2 in respect of a previous fiscal year.
The duties referred to in the first paragraph are, however, deemed to be payable only in respect of the period ending on the latest of the following dates:
(a) the day on which the claim was directly or indirectly filed for the previous fiscal year;
(b) the day on or before which a return was required to be filed for the fiscal year in which the operator sustained the annual loss;
(c) the day on which the return was filed.