Paycheck withholding is an estimate, not the tax. Form W-4 tells the employer how to treat this employee in the payroll tables. Publication 15-T is the set of methods and tables the employer uses. The year’s actual income tax is figured later on Form 1040. Withholding that already went to the Treasury is a credit on that return.
The IRS puts the first half in one sentence. If you are an employee, your employer probably withholds income tax from your paycheck and pays it to the IRS in your name. The amount depends on the income you earn and the information on Form W-4, the Employee’s Withholding Certificate. You specify a filing status. You cannot hand the employer only a dollar amount and skip the rest of the form.
The certificate and the tables
Form W-4, as redesigned in 2020, no longer uses withholding allowances. Publication 15-T for 2026 states that employees now give amounts that raise or lower the tax withheld, and amounts that raise or lower the wage income subject to withholding. The form has five steps. Step 1 — name, address, Social Security number, and filing status — and a dated signature in Step 5 are required. Steps 2, 3, and 4 are adjustments: multiple jobs, dependents, other income, deductions, extra withholding. They affect the calculation only if the employee fills them in.
If those optional steps are blank, the employer withholds from the filing status, the wages, and the payroll period. The employer then uses the Percentage Method or the Wage Bracket Method in Pub. 15-T. A new employee who furnishes no Form W-4 is treated as Single or Married filing separately, with no entries in Steps 2 through 4.
None of that is a household instruction. It is the mechanical path from a certificate to a per-paycheck subtraction.
What the subtraction is not
Federal income tax withholding is not Social Security tax or Medicare tax. Those have their own wage bases and rates in Circular E, Publication 15. The W-4 does not set them. The Social Security wage base for 2026 is $184,500. That figure belongs to FICA, not to the income-tax tables.
Withholding is also not the tax due. Publication 505 explains that the amount withheld is paid to the IRS in the employee’s name, and that the employee takes credit for it on the return. If withholding plus any estimated tax is less than the tax, a balance due — and sometimes a penalty — can appear. If it is more, the difference can come back as a refund. Form W-2 reports the year’s wages and the federal income tax withheld. Form 1040 applies that credit.
The estimate can miss. The tables do not see a second job the W-4 never mentioned, a midyear raise, or a credit that exists only on the return. They see the certificate and the current publication. Self-employment income is a different pipe: estimated tax, not wage withholding.
The year-end ledger
The W-2 is the employer’s annual report of what was paid and what was withheld. The 1040 is the taxpayer’s annual arithmetic. Those two documents meet. The withheld dollars already sent in the employee’s name are applied. What remains is a refund or an amount owed. That meeting is the reconciliation. It is not a verdict on how any one Form W-4 should have been filled out.
Rules, tables, and form revisions change by calendar year. Confirm the current Form W-4 and Publication 15-T at the IRS.
