hour of service
(3) Definition of year of service (A) General rule For purposes of this subsection, the term “year of service” means a 12-month period during which the employee has not less than 1,000 hours of service. For purposes of this paragraph, computation of any 12-month period shall be made with reference to the date on which the employee’s employment commenced, except that, under regulations prescribed by the Secretary of Labor, such computation may be made by reference to the first day of a plan year in the case of an employee who does not complete 1,000 hours of service during the 12-month period beginning on the date his employment commenced. (B) Seasonal industries In the case of any seasonal industry where the customary period of employment is less than 1,000 hours during a calendar year, the term “year of service” shall be such period as may be determined under regulations prescribed by the Secretary of Labor. (C) Hours of service For purposes of this subsection, the term “hour of service” means a time of service determined under regulations prescribed by the Secretary of Labor. (D) Maritime industries For purposes of this subsection, in the case of any maritime industry, 125 days of service shall be treated as 1,000 hours of service. The Secretary of Labor may prescribe regulations to carry out this subparagraph.