Sources
Source library for FERS planning
The primary references used for educational FERS planning content and deterministic rule work.
We link to official references so you can review the underlying guidance yourself. This site remains independent and educational.
Last reviewed 2026-04-25
How sources are selected
FERS Planner prefers OPM pages, OPM FAQs, and OPM handbook material for retirement and benefit rules. Secondary explanations should not override official source language.
When a topic changes over time, such as earnings limits or benefit continuation details, the page should be reviewed before the calculator logic is updated.
How sources are used
Sources inform support content and deterministic rule tests. They are not copied into the calculator as loose text or estimated by an AI model.
Calculation behavior belongs in the deterministic rules engine. Support pages explain the concepts and point readers back to the calculator.