(a) Reportable event. A reportable event occurs for a plan:
(1) Single-cause event. On the date in a plan year when, as a result of a single cause - such as a reorganization, the discontinuance of an operation, a natural disaster, a mass layoff, or an early retirement incentive program - the number of active participants is reduced to less than 80 percent of the number of active participants at the beginning of such plan year or less than 75 percent of the number of active participants at the beginning of the plan year preceding such plan year.
(2) Attrition event. At the end of a plan year if the number of active participants covered by the plan at the end of such plan year is less than 80 percent of the number of active participants at the beginning of such plan year, or less than 75 percent of the number of active participants at the beginning of the plan year preceding such plan year.
(b) Determination rules - (1) Determination dates. The number of active participants at the beginning of a plan year may be determined by using the number of active participants at the end of the previous plan year, and the number of active participants at the end of a plan year may be determined by using the number of active participants at the beginning of the next plan year.
(2) Active participant. “Active participant” means a participant who -
(i) Is receiving compensation for work performed;
(ii) Is on paid or unpaid leave granted for a reason other than a layoff;
(iii) Is laid off from work for a period of time that has lasted less than 30 days; or
(iv) Is absent from work due to a recurring reduction in employment that occurs at least annually.
(3) Employment relationship. The employment relationship referred to in this paragraph (b) is between the participant and all members of the plan's controlled group.
(c) Reductions due to cessations and withdrawals. For purposes of paragraph (a)(1) of this section, a reduction in the number of active participants is to be disregarded to the extent that it -
(1) Is attributable to an event described in ERISA section 4062(e) or 4063(a), and
(2) Is timely reported to PBGC under ERISA section 4063(a).
(d) Waivers - (1) Small plan. Notice under this section is waived if the plan had 100 or fewer participants for whom flat-rate premiums were payable for the plan year preceding the event year.
(2) Low-default-risk. Notice under this section is waived if each contributing sponsor of the plan and the highest level U.S. parent of each contributing sponsor are low-default-risk on the date of the event.
(3) Well-funded plan. Notice under this section is waived if the plan is in the well-funded plan safe harbor for the event year.
(4) Public company. Notice under this section is waived if any contributing sponsor of the plan before the transaction is a public company and the contributing sponsor timely files a SEC Form 8-K disclosing the event under an item of the Form 8-K other than under Item 2.02 (Results of Operations and Financial Condition) or in financial statements under Item 9.01 (Financial Statements and Exhibits).
(e) Extension - attrition event. For an event described in paragraph (a)(2) of this section, the notice date is extended until the premium due date for the plan year following the event year.