5.1. The contributory period of an employee who simultaneously holds, for the first time during a year, more than one employment under the plan is established, for the part of the year where more than one employment is simultaneously held, by retaining a reference employment from among the employments simultaneously held. The reference employment is the employment held by the employee on the day before the day on which more than one employment begin to be held simultaneously or, if none of those employments is held on that preceding day, the employment with the highest annual basic salary.
For each subsequent year, the reference employment retained to establish the contributory period remains the same as long as the employee continues to hold that employment.
The annual basic salary considered is the salary paid or that would have been paid to the employee according to the employment conditions applicable to the employee on the last credited day of the year.