Sources

We aim to ground every tax parameter in an authoritative source. The 2026 federal figures come from the IRS and SSA, and state income tax rates for all 50 states and Washington, D.C. are compiled primarily from the Tax Foundation's annual survey and cross-checked against state revenue departments where available. The references below are the authorities we rely on; results remain estimates and should be verified for your specific situation.

Last source review: August 19, 2026.

• IRS — 2026 tax brackets and standard deduction

  The IRS 2026 inflation-adjustment announcement links Revenue Procedure 2025-32 and lists the final bracket and standard-deduction amounts.

• IRS — FS-2026-13 and Schedule 1-A (qualified overtime deduction)

  The August 2026 IRS questions and answers on the deduction for qualified overtime compensation and the Schedule 1-A phase-out worksheet, used by the no tax on overtime calculator.

• IRS — Schedule 1-A Part II and tipped occupations (qualified tips deduction)

  The Schedule 1-A tips worksheet, the April 2026 final regulations listing tipped occupations (IR-2026-49), and the 2026 Form W-2 box 12 code TP instructions, used by the no tax on tips calculator.

• IRS — Form W-4 (2026) and Publication 15-T Worksheet 1A

  The 2026 Form W-4 steps and Deductions Worksheet, and the employer percentage-method tables, used by the W-4 calculator and guide.

• IRS — Publication 15 (2026), section 7

  Supplemental wage withholding: the 22% flat rate, 37% above $1 million, and the aggregate method, used by the bonus tax calculator.

• IRS — Publication 15-T (2026)

  Official federal payroll withholding methods. PaycheckSimple estimates annual tax liability and documents why an employer's withholding can differ.

• Social Security Administration (SSA)

  Official 2026 Social Security wage base ($184,500) and employee rate (6.2%), plus Medicare rate context.

• Tax Foundation — State Individual Income Tax Rates and Brackets

  Primary cross-state reference for 2026 rates, brackets, standard deductions, and documented model limitations.

• California Franchise Tax Board (FTB)

  California's 2026 estimated-tax instructions specify the deduction and direct taxpayers to the prior-year rate table used for 2026 estimates.

• Illinois Department of Revenue

  Illinois's current 4.95% individual income tax rate and annual personal-exemption updates.

• Florida Department of Revenue

  Official confirmation that Florida does not impose a personal income tax.

• Colorado Department of Revenue

  Colorado's official individual income tax guide and 4.4% rate.

• Georgia Department of Revenue

  Georgia Department of Revenue's 2026 flat-rate update to 4.99%.

• New York State Department of Taxation and Finance

  Official 2026 New York withholding instructions, cross-checked with the 2026 statewide rate table.

• Ohio Department of Taxation — The Finder

  Municipal income tax lookup used to document the local-tax limitation in the Ohio estimate.

• Pennsylvania Department of Revenue

  Pennsylvania's 3.07% personal income tax rate.

• Pennsylvania DCED — Local Income Tax

  Local Earned Income Tax and Local Services Tax rules that are not included in the calculator.

• Louisiana Department of Revenue

  Louisiana's 2025 move to a single flat income tax rate.

• Texas Comptroller

  Confirmation that Texas levies no state personal income tax.

If you spot an inaccuracy, contact us with the relevant IRS or state tax authority link so the estimate and its source can be reviewed together.