Methodology & Editorial Policy

Formula sourcing

Every calculator implements the statute text of the OBBBA provisions (overtime, tips, auto loan interest, senior deduction, and the SALT cap) together with 2026 inflation adjustments published in IRS Rev. Proc. 2025-32 — including the 2026 ordinary income brackets and standard deductions used for the marginal-rate savings estimate.

Verification

Each formula is covered by automated unit tests against hand-computed examples (including the worked examples shown on each page). Tests must pass before any change ships. Figures were last verified against IRS guidance on September 30, 2026.

Simplifications we make

We estimate MAGI from a single income input, apply phase-outs per the statutory ladders (rounding each started $1,000 up), and estimate savings at your marginal federal bracket. We exclude state taxes, credits, AMT, and payroll taxes. These simplifications are noted on each calculator.

Corrections

Spotted an error? Tell us — substantive corrections are applied promptly and noted in the page’s “last updated” date.