5 CFR § 630.209 - Refund for unearned leave.
(1) Require him to refund the amount paid him for the period covering the leave for which he is indebted; or
(2) Deduct that amount from any pay due him.
(b) This section does not apply when an employee:
(2) Retires for disability; or
(3) Resigns or is separated because of disability which prevents him from returning to duty or continuing in the service, and which is the basis of the separation as determined by his agency on medical evidence acceptable to it.