(a) Reportable event. Advance notice is required for a change in a plan's contributing sponsor or controlled group, as described in § 4043.29(a).

(b) Waivers—(1) Small and mid-size plans. Notice under this section is waived with respect to a change of contributing sponsor if the transferred plan has fewer than 500 participants.

(2) De minimis 5-percent segment. Notice under this section is waived if the person or persons that will cease to be members of the plan's controlled group represent a de minimis 5-percent segment of the plan's old controlled group for the most recent fiscal year(s) ending on or before the effective date of the reportable event.