From USPS News Link:
Employees planning to retire or leave the Postal Service should review their electronic earnings statements for a complete listing of annual leave used and earned.
Employees who have taken leave that has not been earned will have to reimburse USPS when they leave or retire. Electronic statements — not the earnings statements USPS mails to employees — include “Annual Leave Advanced, year-to-date” as a separate line.
Employees can review their electronic earnings statements LiteBlue under My HR, Access ePayroll.