(1) In calculating an employee's period of service for purposes of benefit accrual under a defined benefit pension plan, section 204(b)(3) of the Act and section 411(b)(3) of the Code permit the following service to be disregarded: service before an employee first becomes a participant in the plan; service which is not required to be taken into account under section 202(b) of the Act and section 410(b)(5) of the Code (relating to one-year breaks in service for purposes of eligibility to participate); and service which is not required to be taken into account under section 204(b)(3)(C) of the Act and section 411(b)(3)(C) of the Code (relating to 12-consecutive-month periods during which an employee's service is less than 1,000 hours). In addition, in calculating an employee's period of service for purposes of benefit accrual, a defined benefit plan shall not be required to take into account service before the conclusion of a series of consecutive 1-year breaks in service occurs which permits a plan to disregard prior service under section 203(b)(3)(D) of the Act and section 411(a)(6)(D) of the Code.

(2) Example. The following example illustrates paragraph (b)(1) of this section. A plan has a calendar year vesting and accrual computation period and, under § 2530.202-2 (a) and (b)(1), uses eligibility computation periods beginning on an employee's employment commencement date and anniversaries thereof. The plan provides that an employee who has at least 10 years of service has a vested right to 100 percent of his accrued benefit derived from employer contributions. The plan provides that an employee who is credited with at least 1,000 hours of service in a calendar year accrual computation period is credited with at least partial year of participation for purposes of benefit accrual. An employee whose birthday is October 16, 1956, begins employment with an employer maintaining the plan on January 1, 1977. Under § 2530.202-2(a)(1), January 1, 1977 is the employee's employment commencement date and the calendar year 1977 is the employee's initial eligibility computation period. The employee completes at least 1,000 hours of service in each of the calendar years from 1977 through 1981. On January 1, 1982 the employee is admitted to participation in the plan, having met the plan's age requirement (25 years) and service requirement (one year of service) for eligibility to participate. In 1982, the employee is credited with the number of hours of service required for a full year of participation (i.e., more than 1,000 hours of service). Under § 2530.202-2(c), for purposes of applying section 202(b)(4) of the Act and section 410(a)(5)(D) of the Code (relating to years of service completed before a break in service for purposes of eligibility to participate), eligibility computation periods beginning on the employee's employment commencement date and anniversaries thereof are used under the plan to measure service prior to a break in service (in addition, under § 2530.200b-4(a)(2), the same eligibility computation periods are used in measuring one-year breaks in service for purposes of eligibility to participate). Thus, as of January 1, 1983, the employee is credited with six years of service for purposes of eligibility to participate and is credited with one year of participation. In accordance with section 203(b)(1)(A) of the Act and section 411(a)(4)(A) of the Code, the plan provides that years of service completed before age 22 are disregarded for purposes of vesting. As of January 1, 1983, therefore, the employee is credited with four years of service for purposes of vesting. In 1983 the employee terminates employment with the employer, incurring one-year breaks in service in each of the calendar years from 1983 through 1986. As of December 31, 1986, the employee's consecutive one-year breaks in service equal the employee's four years of service for vesting before such breaks. Under section 203(b)(3)(D) of the Act and section 410(a)(5)(D) of the Code and the terms of the plan, the four years of service for vesting completed by the employee before his four consecutive one-year breaks in service are not taken into account for purposes of vesting. Under paragraph (b)(1) of this section, therefore, in calculating the employee's period of service for purposes of benefit accrual, the plan may disregard the year of participation completed by the employee before his four consecutive one-year breaks in service for vesting, because the four consecutive one-year breaks in service equal the four years of service credited to the employee for vesting. The employee is re-employed by the employer on January 1, 1987 completing an hour of service on that date. Under § 2530.200b-4(b)(1), therefore, January 1, 1987 is the employee's reemployment commencement date. In 1987, the employee completes the number of hours of service required for a full year of participation (i.e., more than 1,000 hours of service). For 1987, therefore, the employee is credited with a year of service for purposes of eligibility to participate and vesting, and with a year of participation. As of December 31, 1987, the employee is credited with one year of service for purposes of vesting, since service before the employee's four consecutive one-year breaks in service - including the year of service completed in 1982 - is not taken into account. Because under paragraph (b)(1) of this section, the year of participation credited to the employee for 1982 is not required to be taken into account for purposes of benefit accrual, the employee is credited with one year of participation as of December 31, 1987.