At the end of each payroll calendar year employees with leave balances over the allowed amount are placed in a "use or lose" status. Often times the leave is in fact lost if they do not make arrangements to carry over their balance, donate the leave, or use it; however each of these options requires action on the employees' part including the option to donate the leave.
I believe the unused time should automatically be rolled into a leave bank, accessible by individuals in the agency leave donation programs. This would ensure that each leave donation eligible participant would have at least a predetermined amount of donated leave to use, i.e. 40 or 80 hours while colleagues, friends, and family members took steps to donate their own leave.
By doing so, the government would "save" in increased employee morale, as employees' morale has proven to have a direct correlation to their performance; reduced need for possible government assistance requests by employees in financial hardships; reduced taxpayer/employee default on federally insured debts, i.e. student loans, mortgages, etc..due to financial crisis; reduction in time off if the employee is able to take the extended time needed to handle their emergency collective it may reduce the need for prolonged absences, which decrease overall productivity.
The implementation of such a policy would cost little if anything to implement, as the software to transfer leave is already in place, it would only be a matter of writing a script to automatically transfer balances over a certain amount.