Methodology
How this FERS estimate is built
A plain-English walkthrough of how FERS Planner separates user inputs, deterministic rules, disclosures, and source review.
FERS Planner is independent and not affiliated with OPM. Results are educational estimates, not official benefit decisions.
Last reviewed 2026-04-25
What the calculator does
The calculator collects dates, salary estimates, and a selected V1 retirement scenario. Those inputs are validated before they reach the deterministic rules engine.
The engine decides whether the scenario is inside the current product scope and returns structured output for the result page. UI components do not decide eligibility or duplicate retirement rules.
What the calculator intentionally excludes
The current V1 estimate covers regular immediate, MRA+10 immediate, MRA+10 postponed, and deferred retirement paths for non-USPS FERS employees. It does not make official benefit determinations.
Unsupported cases are not estimated. USPS/PSHB, disability retirement, special provision retirement, and transferred-to-FERS with a CSRS component remain outside V1.
How we handle changes
Each result includes a last-updated date, methodology link, source link, and disclaimer language. When a rule changes, the engine version and support pages should be reviewed together.
Source-backed content is written in plain English first, then converted into deterministic tests before it becomes calculation behavior.