5 C.F.R. § 630.606 – Grant of home leave.

(a) Entitlement. Except as otherwise authorized by statute, an employee is entitled to home leave only when he has completed a basic service period of 24 months of continuous service abroad. This basic service period is terminated by (1) a break in service of 1 or more workdays, or (2) an assignment (other than a detail) to a position in which an employee is no longer subject to section 6305(a) of title 5, United States Code.
(b) Agency authority. A grant of home leave is at the discretion of an agency. An agency may grant home leave in combination with other leaves of absence in accordance with established agency policy.
(c) Limitations. An agency may grant home leave only:
1. (1) For use in the United States, the Commonwealth of Puerto Rico, or a territory or possession of the United States; and
2. (2) During an employee's period of service abroad, or within a reasonable period after his return from service abroad when it is contemplated that he will return to service abroad immediately or on completion of an assignment in the United States.
  Home leave not granted during a period named in paragraph (c)(2) of this section may be granted only when the employee has completed a further substantial period of service abroad. This further substantial period of service abroad may not be less than the tour of duty prescribed for the employee's post of assignment, except when the agency determines that an earlier grant of home leave is warranted in an individual case.
(d) Charging of home leave. The minimum charge for home leave is 1 day and additional charges are in multiples thereof.
(e) Refund for home leave. An employee is indebted for the home leave used by him when he fails to return to service abroad after the period of home leave, or after the completion of an assignment in the United States. However, a refund for this indebtedness is not required when (1) the employee has completed not less than 6 months' service in an assignment in the United States following the period of home leave; (2) the agency determines that the employee's failure to return was due to compelling personal reasons of a humanitarian or compassionate nature, such as may involve physical or mental health or circumstances over which the employee has no control; or (3) the agency which granted the home leave determines that it is in the public interest not to return the employee to his overseas assignment.