Standard Deduction Calculator 2026: methodology
Formulas, constants, and sources used for this calculator.
What this page is
This methodology page explains the formulas, constants, and assumptions used in this calculator.
We publish these details so you can verify how numbers are produced.
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.
Calculator constants (values used)
| Filing status | Value used | Notes |
|---|---|---|
| Single | $15,500 | 2026 statutory projection |
| MFJ | $31,000 | 2026 statutory projection |
| HOH | $23,250 | 2026 statutory projection |
How the calculation works
We select a base standard deduction using your filing status.
We add additional standard deduction amounts if you (or your spouse) are age 65+.
We then estimate taxable income by subtracting the deduction from the AGI you entered.
Rounding and formatting
We round to the nearest cent for dollar amounts.
This tool is designed for planning and education, not as a substitute for official IRS worksheets.
Sources
- IRS (irs.gov) annual inflation adjustment releases
- IRS publications and instructions (Form instructions)
- SSA.gov for Social Security related thresholds (when applicable)
Note: Values reflect projected inflation adjustments based on IRS statutory formulas. We update our models as new IRS bulletins are published.