FERS creditable service can include:
(for more

specific details, see the related articles listed below)

- generally the period of time from each date of appointment to date of

separation (when deductions were paid into the retirement system)

- Leave without pay (LWOP) if it does not exceed six months within a calendar

year

- Part-time service

- Intermittent service (time actually served, WAE

[when-actually-employed]) - up to 260 days a year.

- workers compensation is creditable if the employee returns to duty

- breaks in service of up to 3 days

- Deposit service  (time employee worked for federal government but

there were no dedeductions for FERS retirement, if performed before January

1, 1989). 

- Military service

- Unused sick leave  (only used to extend length of service for FERS

employees who transferred from CSRS and have a CSRS component to their

retirement annuity).