The designated payor of each plan shall pay the premiums imposed by the corporation under this subchapter with respect to that plan when they are due. Premiums under this subchapter are payable at the time, and on an estimated, advance, or other basis, as determined by the corporation. Premiums imposed by this subchapter on September 2, 1974 (applicable to that portion of any plan year during which such date occurs) are due within 30 days after such date. Premiums imposed by this subchapter on the first plan year commencing after September 2, 1974, are due within 30 days after such plan year commences. Premiums shall continue to accrue until a plan’s assets are distributed pursuant to a termination procedure, or until a trustee is appointed pursuant to section
of this title, whichever is earlier. The corporation may waive or reduce premiums for a multiemployer plan for any plan year during which such plan receives financial assistance from the corporation under section
of this title, except that any amount so waived or reduced shall be treated as financial assistance under such section.