Creditable Service Q2
Active military service after 1956 (including active duty that interrupts federal civilian service) may be credited for title to and computation of federal retirement benefits, so long as it was not included in the computation of military retired pay (or if it was included in retired pay, the retired pay was awarded based on disability incurred in the line of duty during a period of war or certain other circumstances), you will receive retirement credit only if a deposit for the military service is made.

There is an exception if you transferred from CSRS to FERS and have a CSRS component to your annuity. In that case, for military service before the transfer:

If you were first employed under CSRS on or after October 1, 1982, you must make the deposit to receive service credit.

If you were first employed under CSRS before October 1, 1982, you may either make the deposit or receive service credit but have your annuity recomputed to eliminate post-1956 military service if you are eligible for Social Security at age 62 or at retirement, if later.

Any deposit normally must be made before retirement.

See Chapter 3, Section 3 of the Federal Employees Almanac for information about calculating and making these deposits.