Anyone who got rehired after 1984, and had 5 years prior service under CSRS, falls into the CSRS offset category. Couldn't keep CSRS in full.
I hired on permanent in 1986, never had a choice, stuck automatically in FERS, less than 5 years prior CSRS service, so I didn't fall into the Offset category. But because my prior temporary-hire GS-time (<5yrs total service) occurred prior to 1989, I was allowed to buy back that time, so that it would count timewise towards retirement and the FERS annuity. The payback amount was minimal monetarily since I paid it back over 10 years ago, but it gave me half-year additional time towards retirement, which means I can retire half a year earlier than otherwise. It was worth it for that reason alone.
The people who fall into the Offset category (I have a friend who did), may need to go to extra effort to get their retirement calculated correctly, and it may take extra time to get it fully straightened out, even after they retire. My CSRS-offset friend went for over a year trying to get her retirement fully straightened out, and didn't receive full retirement pay until it was. She had more than 5 years CSRS time in prior to 1984, resigned to take critical time in her family life to raise kids, then was rehired after 1984, but before 1989. Because she was rehired during the CSRS-FERS transition years (1984-1989), she got full credit for her prior CSRS service once she repaid the CSRS retirement monies she had previously pulled out when she resigned to raise kids. So for her, her retirement consists of 5+years CSRS-retirement pay, and then x years of FERS/SS pay beyond those CSRS pay credits.
There were never a lot of people who fell into that Offset situation, so many HR specialists had a hard time figuring out the right amount of retirement credits and correct retirement pay due. If anyone here is in the Offset-boat, pay close attention when HR runs your retirement math. they may get it wrong the first time around.
