Sources & Citations

Every paycheck calculation in TakeHome IQ traces to a published authority. This page lists those authorities, grouped by jurisdiction, with the date each was last verified. If a citation goes stale or a URL changes, the dated entry below is what flagged it.

For a step-by-step walk-through of how these sources are used in the math, see How TakeHome IQ Calculates Your Paycheck.

Federal Authorities

Federal income tax withholding follows IRS Publication 15-T, Worksheet 1A. FICA rates and supplemental wage rules come from IRS Publication 15. The Social Security wage base is published annually by the SSA.

• IRS Publication 15-T — Federal Income Tax Withholding Methods
• IRS Publication 15 — Employer’s Tax Guide (Circular E)
• IRS Form W-4 — Employee’s Withholding Certificate
• IRS Form W-4 instructions
• IRS Publication 505 — Tax Withholding and Estimated Tax
• SSA Contribution and Benefit Base (Social Security wage base)

State Withholding Guides

Each state with an income tax publishes its own employer withholding guide. The list below covers the states with dedicated paycheck pages on this site. States with no income tax (Florida, Texas, etc.) follow federal-only withholding for income tax; FICA and state-specific add-ons (e.g., disability insurance) still apply where the state requires them.

Verification Cadence

Tax tables are reviewed each January when the IRS and state DORs publish updated withholding tables for the new tax year. URLs above are checked at the same time. State coverage is expanding — if a state isn’t listed yet, the calculator still runs federal withholding correctly and the state guide for that jurisdiction will be added with its citations when the page ships.

Last verified: 2026-05-08.

Spot a broken link, an outdated citation, or a missing source? Email me — corrections land in the next verification pass.