Q: If I retire under FERS with 36 years of service prior to age 66 when I could receive the full Social Security amount, how is the supplement calculated or valued? Same as SS is calculated?
A: The supplement is payable up to age 62, when you first become eligible for Social Security on your own account, it is not payable until your Social Security Full Retirement Age.
If you had 36 full years of FERS civilian service, and were under the age of 62, your supplement would be 36/40 (90%) of your age 62 estimated benefit.