A GS-14 in Washington, D.C. retires at age 60 with 28 years of service.

Her neighbor, also a GS-14 with identical tenure, waits just two more years — to age 62 with 30 years. The second retiree collects roughly $6,200 more per year, every year, for the rest of her life. That gap compounds to over $150,000 by age 85 — all because of a single percentage-point shift in the FERS formula.

Understanding exactly where that shift kicks in, and how the underlying variables interact, is the difference between advising a federal client competently and leaving six figures on the table. FERS is a defined-benefit pension — one of three income legs available to federal civilians alongside Social Security and the TSP. Unlike a 401(k) balance that fluctuates with markets, the FERS annuity is a guaranteed monthly check for life, backed by the full faith and credit of the United States government.