(3) (A) For purposes of this paragraph, the term “1-year break in service” means a calendar year, plan year, or other 12-consecutive-month period designated by the plan (and not prohibited under regulations prescribed by the Secretary) during which the participant has not completed more than 500 hours of service. (B) For purposes of paragraph (1), in the case of any employee who has any 1-year break in service, years of service before such break shall not be required to be taken into account until he has completed a year of service after his return. (C) For purposes of paragraph (1), in the case of any participant in an individual account plan or an insured defined benefit plan which satisfies the requirements of sub section 1054(b)(1)(F) of this title who has 5 consecutive 1-year breaks in service, years of service after such 5-year period shall not be required to be taken into account for purposes of determining the nonforfeitable percentage of his accrued benefit derived from employer contributions which accrued before such 5-year period. (D) (i) For purposes of paragraph (1), in the case of a nonvested participant, years of service with the employer or employers maintaining the plan before any period of consecutive 1-year breaks in service shall not be required to be taken into account if the number of consecutive 1-year breaks in service within such period equals or exceeds the greater of— (I) 5, or (II) the aggregate number of years of service before such period. (ii) If any years of service are not required to be taken into account by reason of a period of breaks in service to which clause (i) applies, such years of service shall not be taken into account in applying clause (i) to a subsequent period of breaks in service. (iii) For purposes of clause (i), the term “nonvested participant” means a participant who does not have any nonforfeitable right under the plan to an accrued benefit derived from employer contributions. (E) (i) In the case of each individual who is absent from work for any period— (I) by reason of the pregnancy of the individual, (II) by reason of the birth of a child of the individual, (III) by reason of the placement of a child with the individual in connection with the adoption of such child by such individual, or (IV) for purposes of caring for such child for a period beginning immediately following such birth or placement, the plan shall treat as hours of service, solely for purposes of determining under this paragraph whether a 1-year break in service has occurred, the hours described in clause (ii). (ii) The hours described in this clause are— (I) the hours of service which otherwise would normally have been credited to such individual but for such absence, or (II) in any case in which the plan is unable to determine the hours described in subclause (I), 8 hours of service per day of absence, except that the total number of hours treated as hours of service under this clause by reason of such pregnancy or placement shall not exceed 501 hours. (iii) The hours described in clause (ii) shall be treated as hours of service as provided in this subparagraph— (I) only in the year in which the absence from work begins, if a participant would be prevented from incurring a 1-year break in service in such year solely because the period of absence is treated as hours of service as provided in clause (i); or (II) in any other case, in the immediately following year. (iv) For purposes of this subparagraph, the term “year” means the period used in computations pursuant to paragraph (2). (v) A plan may provide that no credit will be given pursuant to this subparagraph unless the individual furnishes to the plan administrator such timely information as the plan may reasonably require to establish— (I) that the absence from work is for reasons referred to in clause (i), and (II) the number of days for which there was such an absence.