Methodology & Sources

Source authorities

All tax rules, brackets, and thresholds used across USTaxTools calculators come directly from the Internal Revenue Service (IRS), the Social Security Administration, and each state's department of revenue where state-level figures apply.

Update cadence

We review calculators each January for the new tax year and again when the IRS publishes mid-year inflation adjustments or rule changes. Every calculator page displays its own "Last updated" date, sourced from the file's last git commit.

Where the math lives

Calculation logic lives in tested TypeScript files under src/utils/, separated from UI, so every number shown can be traced back to a tested function.

Handling ambiguous rules

Where IRS guidance is ambiguous or depends on personal facts we can't observe (residency, dependents, credits eligibility), calculators use the most common interpretation and flag the assumption inline.

Not financial advice

USTaxTools provides general information only. It is not tax, legal, or financial advice. For a binding answer, speak to a licensed tax professional.