Civil Service Personnel Rule 55

55. The following periods are to be included in calculating the increment:
(a) the duration of full time service at the post for which the increment is entitled;
(b) the duration of fulltime service at the post similar to or higher than the past for which the increment is entitled;
(c) if the promotion occurs during on duty period or study period abroad, the period of increment shall be calculated from the starting date of promotion;
(d) temporary suspension period which is treated as on duty;
(e) leave periods on leave pay;
(f) the period of leave without pay allowed to be included in calculating the increment by the authorized person in case of leave without pay was on ground of illness or for any unavoidable cause;
(g) the period of deputation on external service regulations;
(h) the period calculated from the starting date of promotion if being promoted at the parent department during deputation on external service regulations;
(i) periods treated as full time service in particular cases by the relevant service personnel organization in accordance with the laws, regulations and by-laws;
(j) when calculating increments, only the eligible periods will be counted after leaving out the ineligible ones.