(i) A plan's defined benefit formula provides that the annual retirement benefit shall be 2 percent of the average compensation in all years of participation multiplied by the number of years of participation. Employee A is a full-time employee who has completed 2,000 hours during each of 20 accrual computation periods. A's average hourly rate was $5 an hour. Thus, A's average compensation for each year during participation in the plan is $10,000 ($5 per hour multiplied by 2,000 hours). If the plan states that a full year of participation is 2,000 hours, then A's annual retirement benefits, if he retired at that time, would be $4,000 ($10,000 per year of compensation × .02 × 20 years of participation). Employee B, however, is a part-time employee who completes 1,000 hours of service during each of 20 accrual computation periods. Like A, B's average hourly rate is $5 per hour. B's average compensation for his total years of participation is $5,000 ($5 per hour multiplied by 1,000 hours). Thus, the plan's benefit formula, by basing benefits on an employee's average compensation in all years of participation, in effect prorates benefits to reflect the fact that during B's participation in the plan, he has earned less than the maximum compensation that a full-time employee paid at the same rate could earn during the same period of participation in the plan. Under the rule of subparagraph (1), therefore, the plan is not permitted to prorate B's years of participation to reflect B's less than full-time employment throughout his participation in the plan. Therefore, B's annual retirement benefit would be $2,000 ($5,000 average compensation × .02 × 20 years of participation). (If double proration were permitted, then B's total years of participation would be only 10 since he would be credited with only one-half of a year of participation during each of the accrual computation periods (1,000/2,000). Thus, B's annual retirement benefit would be $1,000—i.e., $5,000 average compensation × .02 × 10 years of participation.)
(ii) If the plan adjusts the average compensation during plan participation to reflect full compensation, then the plan may prorate years of participation. Thus, the average full annual compensation for B would be $10,000 rather than the $5,000 actually paid. Employee B's annual retirement benefit would then be $2,000 ($10,000 average full compensation × .02 × 10 years of participation).