(a) The effective date on which an employee (otherwise eligible thereunder) becomes subject to section 6304(b) of title 5, United States Code, is the:

(1) Date of his entry on duty when he is employed locally;

(2) Date of his arrival at a post of regular assignment for duty; or

(3) Date on which he begins to perform duty in an area outside the United States and the area of recruitment or from which transferred, when the employee is required to perform duty en route to his post of regular assignment for duty.

(b) Subject to section 6304(c) of title 5, United States Code, the maximum amount of annual leave that may be carried forward into the next leave year by an employee who is transferred or reassigned to a position in which he is no longer subject to section 6304(b) of that title is determined as follows:

(1) When, on the date prescribed by paragraph (c) of this section, the amount of an employee's accumulated and accrued annual leave is 30 days or less, he may carry forward the amount prescribed by section 6304(a) of title 5, United States Code;

(2) When, on the date prescribed by paragraph (c) of this section, the amount of an employee's accumulated and accrued annual leave is more than 30 days but not more than 45 days, he may carry forward the full amount thereof that is unused at the end of the current leave year;

(3) When, on the date prescribed by paragraph (c) of this section, the amount of an employee's accumulated and accrued annual leave is more than 45 days, he may carry forward the amount of unused annual leave to his credit at the end of the current leave year that does not exceed:

(i) 45 days, if he is not entitled to a greater accumulation under section 6304(c) of title 5, United States Code; or

(ii) The amount he is entitled to accumulate under section 6304(c) of that title, if that amount is greater than 45 days.

(c) For the purposes of paragraph (b) of this section, an agency shall determine the amount of an employee's accumulated and accrued annual leave at the end of the pay period which includes:

(1) The date on which the employee departs from his post of regular assignment for transfer or reassignment, except that when the employee is required to perform duty en route in an area in which he would be subject to section 6304(b) of title 5, United States Code, if assigned there, it is the date on which he ceases to perform the duty; or

(2) The date on which final administrative approval is given to effect a change in the employee's duty station when he is on detail or leave in the United States, or in an area (the Commonwealth of Puerto Rico or a territory or possession of the United States) from which he was recruited or transferred.