How it works

Every formula. Every assumption. Every source.

Six OPM-sourced formula modules — regression-tested before every release. Every assumption disclosed. Every output citable. This is how FedHorizon earns your trust.

Formula engine

Six OPM-sourced formula modules

The same engine powers every report FedHorizon ships. Tap any module to see the formula, plain-English explanation, and OPM source.

Built
FERS pension engine
Standard 1.0% multiplier, 1.1% at age 62 with 20+ years, MRA by birth year, High-3 calculation, and OPM's 80% cap. Every edge case tested against published OPM examples.
Plain English

Your pension is calculated by multiplying your years of service by a percentage of your highest 3-year average salary. If you retire at 62 or later with at least 20 years of service, that percentage bumps up from 1.0% to 1.1% — worth about $1,000–$2,000/year for a typical federal employee.

Formula
Edge cases
  • The 1.1% boost only applies when BOTH conditions are met — age 62+ AND 20+ years. Age 62 with 19 years gets 1.0%.
  • The 80% cap: no pension can exceed 80% of your High-3, regardless of years of service.
  • High-3 is the average of your 3 highest consecutive years of base pay — not your final salary.
  • Part-time service is prorated: a year at 50% time counts as 0.5 years.
OPM source

OPM FERS Handbook, Chapter 50 (Sections 50A–50B). Appendix A for MRA table.

Built
Special category engine
1.7% multiplier for first 20 covered years, 1.0% thereafter. LEO/FF mandatory retirement at 57, ATC at 56. VERA eligibility at 50+20. Supported at MVP launch.
Plain English

Law enforcement officers, firefighters, air traffic controllers, and border protection officers earn a higher pension rate for their first 20 years: 1.7% per year instead of 1.0%. This recognizes the physical demands of the job. After 20 covered years, additional years accrue at the standard 1.0%.

Formula
Edge cases
  • Mandatory retirement: LEO/FF must retire by 57; ATC by 56. Waivers are rare and must be requested annually.
  • VERA eligibility: special category employees can retire at age 50 with 20 covered years.
  • The 1.7% rate applies only to covered service — years in a non-special position don't qualify for the higher rate.
  • The 80% cap still applies — typically reached around 40+ covered years.
OPM source

OPM FERS Handbook, Chapter 50, Section 50C. 5 U.S.C. 8415(d).

Built
Supplement eligibility engine
MRA+30 and age 60+20 eligibility. Monthly supplement formula (SS62 × FERS years ÷ 40). Earned income reduction rule applied. Ineligibility correctly flagged.
Plain English

If you retire before age 62, you may receive the FERS Supplement — a bridge payment that approximates the Social Security benefit you've earned through federal service. It stops at 62 when Social Security can begin. The supplement is reduced if your earned income exceeds the annual limit (similar to Social Security's earnings test).

Formula
Edge cases
  • Not available under MRA+10 early retirement — only full-eligibility retirements qualify.
  • Disability retirees and special category retirees have different rules.
  • Investment income, rental income, and Social Security itself do NOT count toward the earnings limit.
  • The supplement is fully taxable as ordinary income.
OPM source

OPM FERS Handbook, Chapter 51 (FERS Annuity Supplement). 5 U.S.C. 8421.

Built
Survivor election engine
0%, 25%, and 50% election cost, spouse monthly income, and break-even age per election. Section 4 of every report.
Plain English

When you retire, you choose how much survivor benefit to leave your spouse. A larger election costs you more pension now, but protects your spouse if you die first. The engine calculates your cost, your spouse's monthly benefit, and the break-even age — how long you'd need to live for the reduced pension to cost more than the survivor benefit is worth.

Formula
Edge cases
  • If you elect no survivor benefit, your spouse must consent in writing — OPM requires notarized spousal waiver.
  • Former spouse court orders (QDRO equivalents) can override your election.
  • The survivor benefit is not just for death — it also continues through divorce if a court orders it.
  • FEHB coverage for a surviving spouse requires either the full or partial survivor election.
OPM source

OPM FERS Handbook, Chapter 70 (Survivor Benefits). 5 U.S.C. 8442.

Built
TSP projection engine
Balance at multiple retirement ages under conservative, moderate, and aggressive return assumptions. Traditional vs. Roth comparison. Agency match gap identification.
Plain English

Your TSP balance at retirement depends on how much you contribute, how long it compounds, and what the market returns. The engine projects your balance under three scenarios — conservative (4%), moderate (6%), and aggressive (8%) — and compares Traditional vs. Roth tax treatment. It also flags if you're leaving any agency match on the table.

Formula
Edge cases
  • Standard catch-up ($8,000 extra in 2026) available at age 50+ — the engine includes these.
  • Super catch-up ($11,250 extra in 2026) available for ages 60–63 under SECURE Act 2.0.
  • Agency match is always Traditional, even if your own contributions are Roth.
  • The engine uses nominal returns — inflation-adjusted comparisons are shown separately in the report.
  • TSP contribution limits: $24,500 employee + $8,000 catch-up (2026 limits, updated annually).
OPM source

TSP.gov Bulletin 25-3 (2026 limits). IRS Notice 2025-67. SECURE Act 2.0 109 (super catch-up).

Phase 2
Military buyback engine
Deposit calculation (3% of military pay + interest), pension uplift, payback period, and Special Category threshold interaction.
Plain English

If you served in the military before your federal civilian career, you can 'buy back' that service time to add it to your FERS years of service. The cost is 3% of your military base pay for those years, plus interest. In return, your pension increases — and you may cross key thresholds (like 20 years for the supplement, or 30 years for MRA+30 retirement).

Formula
Edge cases
  • You cannot count military years AND collect military retired pay simultaneously — you must waive one.
  • Reserve/National Guard retirement (20+ qualifying years) is treated differently than active duty.
  • Interest accrues from your federal hire date — earlier deposits cost significantly less.
  • Military years can push a standard employee over the 20-year threshold to qualify for the FERS Supplement.
OPM source

OPM FERS Handbook, Chapter 23 (Military Service). 5 U.S.C. 8332.

Design principles

How accuracy is maintained

Every release goes through the same verification process before anything ships.

OPM-sourced only
Every formula is built directly from published OPM documentation — CSRS/FERS Handbook, CFR citations, and official TSP guidance. No third-party assumptions, no interpolation.
Regression-tested before every release
All formula modules are tested against OPM's own published examples. A golden scenario test suite blocks any deployment that changes a verified output.
Deterministic outputs
The engine is stateless and deterministic. Identical inputs always produce identical outputs — no randomness, no variability. Every calculation is fully auditable.
Plain-English explanations. Every number traces to a formula.
Report explanations are generated from validated engine outputs only. They never modify, recalculate, or interpolate any number. Every figure has a formula source.
Annual data refresh
FEHB premium data is refreshed each October. TSP contribution limits updated each January. OPM rule changes monitored continuously via Federal Register.