(a) Every distributor and unclassified exporter, as defined in paragraphs (c) and (j) of section one of chapter sixty-four A, shall, on or before the twentieth day of each month file with the commissioner a return stating the number of gallons and the selling price of fuel sold by him in the commonwealth or exported or caused to be exported from the commonwealth during the preceding calendar month and such other information as the commissioner may deem necessary.

Every unclassified importer, as defined in paragraph (i) of section one of chapter sixty-four A, shall, on or before the twentieth day of each month file with the commissioner a return stating the number of gallons of fuel imported or caused to be imported into the commonwealth during the preceding calendar month, and such other information as the commissioner may deem necessary, including information relative to the cost of such fuel by type.

[There is no subsection (b).]