Publication 15-T (2026), Federal Income Tax Withholding Methods
Worksheet 1A, pay periods, W-4 Steps 2–4, annual percentage-method tables, standard annual adjustment, rounding boundary.
Open Internal Revenue Service source ↗Official sources
Every rate has a responsible authority
This page explains which calculation each source supports. A provider comparison is not used as legal authority.
Publication 15 (2026), Employer's Tax Guide
Social Security employee and employer rates, Medicare rates, Social Security wage base, Additional Medicare withholding threshold.
Open Internal Revenue Service source ↗Contribution and Benefit Base
$184,500 Social Security wage base, 6.2% employee and employer rates.
Open Social Security Administration source ↗Form W-4 (2026), Employee's Withholding Certificate
field labels and employee-election boundaries.
Open Internal Revenue Service source ↗