Effective Tax Rate Explained - Methodology & Sources
Transparent explanation of formulas, constants, and IRS data sources used.
Data Sources
Primary data sourced from official IRS publications and annual inflation adjustments.
Calculation Formula
Calculations follow IRS-defined thresholds and phaseout formulas. When inside a phaseout range, contribution or deduction amounts are proportionally reduced according to IRS worksheets.
Constants Used
We use IRS-published annual limits, thresholds, and phaseout ranges for the relevant tax year. Values are updated when the IRS publishes new inflation adjustments.
Calculation Approach
Formulas are based on IRS-defined limits and thresholds. Employee limits, total caps, and catch-up contributions are applied per published guidance.
Assumptions
- No plan-specific employer restrictions included
- No state tax adjustments applied
- Assumes standard IRS rules