Data Sources

Every number in our calculators traces back to one of the sources below. We refresh annually after the IRS Revenue Procedure release.

• IRS Revenue Procedure 2025-32 (2026 inflation adjustments)
• IRS Publication 17 — Your Federal Income Tax
• IRS Publication 505 — Tax Withholding and Estimated Tax
• IRS Publication 590-A / 590-B — IRAs
• IRS Notice 2025 — Retirement contribution limits
• Social Security Administration — 2026 wage base
• Tax Foundation — State individual income tax rates and brackets
• Tax Foundation — State and Local Sales Tax Rates
• State Departments of Revenue (linked individually inside each state guide)

See our methodology for how these sources feed into each calculator, and the editorial policy for our review process.