Methodology

Each calculator page has its own "Methodology" and "Limitations" sections with formula-level detail. This page covers the shared data sources and how often they're updated.

Data sources

• Federal tax brackets, standard deduction (Single & MFJ): IRS Rev. Proc. 2025-32, tax year 2026.
• Head-of-Household bracket thresholds below the 24% band: currently estimated by scaling 2025 figures forward, pending direct verification against the full text of Rev. Proc. 2025-32. This is disclosed, not hidden, in the underlying data file.
• Social Security wage base ($184,500 for 2026): corroborated across multiple secondary sources; pending direct confirmation against the Social Security Administration's official 2026 fact sheet.
• Additional Medicare Tax thresholds: set by statute (IRC §3101(b)(2)), not inflation-adjusted, unchanged since 2013.
• State income tax: currently modeled for no-income-tax states plus a handful of flat-rate approximations. Most states with progressive tax brackets are not yet modeled — the calculators disclose this per state rather than silently guessing.

Update cadence

Federal figures are tied to a specific tax year and are reviewed each time the IRS publishes new inflation-adjusted figures (typically each autumn for the following tax year). State data is a work in progress — see the note on each calculator if your state isn't yet covered.

What these tools don't do

They don't file taxes, store any data (all calculations run in your browser and nothing is sent to a server), or account for every deduction, credit, or state-specific rule that could apply to your situation. They're planning estimates, not substitutes for a tax professional.