From USPS News Link:
Employees working under the Federal Employees Retirement System (FERS) who are planning to retire this year are advised to review how unused sick leave will be credited as service when calculating retiree benefits.
FERS employees who retire between now and Dec. 31, 2013 will have 50 percent of their earned sick leave credited toward service time. Those who retire after Dec. 31, 2013, will have all unused sick leave credited.
As of Jan. 1, 2014, FERS retirees will join Civil Service Retirement System (CSRS) retirees in having all unused sick leave credited.
When unused sick leave is computed in an annuity, it can add to the amount an employee receives every month in an annuity.
Employees should note that unused sick leave does not count towards the time required for retirement eligibility, and is not credited for deferred retirements.