Every packer, live poultry dealer, stockyard owner, market agency, and dealer (except a packer buyer registered to purchase livestock for slaughter only) shall file annually with the Administration a report on prescribed forms not later than April 15 following the calendar year end or, if the records are kept on a fiscal year basis, not later than 90 days after the close of his fiscal year. The Administrator on good cause shown, or on his own motion, may grant a reasonable extension of the filing date or may waive the filing of such reports in particular cases.