Federal paycheck withholding basics (Pub 15-T)

Last reviewed: 2026-10-02. Confirm figures against official IRS / DIR sources before filing or paying.

Every W-2 paycheck with federal income tax withheld is running a recipe from the IRS. The detailed cookbook for the methods is Publication 15-T, Federal Income Tax Withholding Methods. Pub 15 (Circular E) is the broader employer’s tax guide; Pub 15-T focuses on how to figure the federal income tax withholding amount itself.

This article translates the moving parts into plain English for workers and small-business readers—without pretending a blog post replaces the publication’s worksheets and tables.

What Pub 15-T is (and is not)

Is: The IRS publication that explains how employers (and certain pension payers) figure federal income tax withholding using the Percentage Method and Wage Bracket Method, including worksheets that work with modern Form W-4 entries.

Is not: A personal tax-return instruction booklet, a state withholding manual, or a promise of your final Form 1040 balance due. Withholding is a pay-as-you-go estimate toward annual income tax.

For the current edition, start at Publication 15-T on IRS.gov (2026 edition available as of this review).

Form W-4: the employee inputs that drive the machine

Since the 2020 redesign, Form W-4 no longer uses “allowances” the old way. In plain educational terms, employees complete steps that tell payroll:

Filing status (affects which table/column logic applies)
Multiple jobs / spouse works themes (Step 2)
Claim dependents / other credits (Step 3)
Other income, deductions, and extra withholding (Step 4)
Whether claiming exemption from withholding when eligible ( mechanices updated over time—2026 Form W-4 materials note a checkbox approach below Step 4(c) rather than writing “Exempt” in older fashion)

If your life changes—marriage, new job, side income, big deduction shift—file a new W-4. Pub 15-T methods can only be as good as the certificate on file.

Related reading on this site: Reading a paycheck: gross vs net.

Two headline methods employers use

Pub 15-T describes multiple approaches. Two dominate conversation:

1) Percentage Method (common in automated payroll)

Educational outline of the spirit of Worksheet 1A–style percentage method for wages:

Start from taxable wages for the pay period (after applicable pre-tax deductions).
Adjust using Form W-4 Step information (multiple jobs, dependents, other income, deductions, extra withholding).
Annualize or otherwise map wages into the publication’s percentage method tables for the filing status / pay frequency.
Compute tentative annual withholding, convert back to the pay period.
Apply Step 3 credit-dollar reductions and Step 4(c) additional withholding as directed by the worksheet.

Automated systems implement these steps in software. The publication’s tables change when Congress changes rates, standard deductions, or related law. The 2026 Pub 15-T “What’s New” notes updates tied to legislation commonly referenced as P.L. 119-21 (including permanent extension themes for individual rates and standard deduction, and personal exemption termination themes originally from TCJA). Always use the edition matching the pay date’s tax year.

2) Wage Bracket Method (manual-friendly tables)

The wage bracket method uses lookup tables: find the wage range for the pay period and filing status, then read the withholding amount, with adjustments for W-4 steps as the publication instructs. It is handy for manual payroll but has practical limits at higher wage levels—Pub 15-T tells employers when to switch to the percentage method.

Neither method is “your exact tax.” Both estimate withholding for the period.

Supplemental wages (bonus / OT paid separately) — awareness only

Employers sometimes pay bonuses or other supplemental wages using optional flat-rate withholding or aggregate methods described in Pub 15 / Pub 15-T cross-references. A bonus check that withholds at a flat percentage can feel like a huge tax hike even when annual tax is milder. That is a withholding-method effect, not automatically a permanent bracket change on all salary.

This article does not reproduce every supplemental-wage rule—see the current Pub 15 section on supplemental wages and Pub 15-T notes.

FICA is separate from Pub 15-T income tax withholding

Pub 15-T is about federal income tax withholding methods. Social Security and Medicare employee taxes are separate FICA computations:

Social Security employee share: 6.2% up to the annual wage base ($184,500 for 2026 per SSA)
Medicare employee share: 1.45% (Additional Medicare Tax may apply above thresholds)

Those lines can be correct even when income-tax withholding looks high or low relative to your annual plan. Do not use Pub 15-T tables to “check” FICA.

How withholding connects to estimated tax and side hustles

If you have a W-2 job and freelance income, paycheck withholding alone may not cover total tax—including self-employment tax on net freelance profit. Options include:

Extra withholding on Form W-4 Step 4(c)
Estimated quarterly payments via Form 1040-ES

See Estimated quarterly taxes for freelancers (intro) and 1099 vs W-2 paperwork differences.

Plain-English walkthrough (toy numbers)

Facts (fictional): Semi-monthly employee, single filing status, no Step 2 checkbox, no Step 3 dependents, no Step 4 adjustments. Taxable wages for federal income tax this period: $2,000 after pre-tax benefits.

What payroll does conceptually: Maps $2,000 semi-monthly wages into Pub 15-T’s method for “Single” / applicable table, producing a federal income tax withholding amount for the period—say $X from the official table (we intentionally do not paste copyrighted table rows here). Then Social Security and Medicare apply to FICA wages separately.

What you should do as a worker: Compare paystub federal withholding YTD against the IRS Tax Withholding Estimator mid-year. Adjust W-4 if you are wildly over- or under-withheld—not because a blog invented a number.

Pay frequency changes the table lookup—not your annual tax law

Weekly, biweekly, semimonthly, and monthly wages map into different rows or annualization factors inside Pub 15-T. Two employees with the same annual salary can see slightly different per-check withholding solely because one is paid biweekly (26 checks) and one semimonthly (24 checks). Over a full year, well-implemented methods aim at similar totals for the same W-4—but early-year stub comparisons across employers confuse people who ignore pay frequency.

For a current withholding estimate, match pay frequency and wages in Pub 15-T, payroll software, or the IRS Tax Withholding Estimator; changing pay frequency changes the period calculation.

Mid-year W-4 fixes (practical)

If you discover under-withholding in September, increasing Step 4(c) extra withholding on each remaining check can still help you avoid a spring balance due—sometimes more effectively than waiting for a single estimated payment if you prefer paycheck mechanics. Conversely, chronic over-withholding is an interest-free loan to the government; adjust thoughtfully using the IRS estimator rather than zeroing withholding casually.

Pub 15-T will happily withhold almost nothing if a W-4 claims exemption improperly—or withhold a lot if Step 4(c) is set high. The publication follows the form; it does not moralize.

Using withholding estimates responsibly

A withholding estimate is useful for planning, but it is not a tax bill. For current calculations, use Pub 15-T, payroll software, or the IRS Tax Withholding Estimator. Simplified estimates may omit worksheet details, pre-tax nuances, or state modules.

If an estimate and your stub disagree, trust payroll software running current Pub 15-T—or ask payroll—after checking your W-4 and pre-tax elections.

Common employee misunderstandings

“Withholding = tax bill.” Withholding is a prepayment. Form 1040 settles up.
“Changing jobs mid-year broke the tables.” Multiple jobs without Step 2 adjustments often under-withhold.
“A bonus taxed at a flat rate means I’m in that bracket forever.” Supplemental methods can differ from annual marginal rates.
“Pub 15-T sets my state tax.” State agencies publish their own methods (for example, California FTB withholding schedules).
“Exempt on W-4 means no FICA.” Exemption from income tax withholding is a narrow claim; FICA rules differ.

Employer checklist (educational)

Use the Pub 15-T edition for the correct year
Store the current Form W-4
Apply pre-tax deductions in the order your plan and IRS rules require
Separate income tax withholding from FICA
Treat California overtime gross-up correctly before withholding (earnings accuracy first)
Do not invent tables from memory after a law change

Related MileagePayTools guides and tools

Official sources

FAQ

Which method is “better,” percentage or wage bracket?

For eligible wages, both aim to implement IRS withholding rules. Automated payroll usually uses the percentage method worksheets. Accuracy depends on correct wages, W-4, and current tables—not on marketing language.

Does Pub 15-T tell me my refund?

No. Refunds depend on total payments vs total tax on the annual return.

Should I copy table percentages into a spreadsheet?

Prefer official publications or payroll software. Homemade tables go stale after law changes and are easy to mis-apply across pay frequencies.

Where do California employees look for state withholding?

California Franchise Tax Board publishes employer withholding schedules and guidance separate from Pub 15-T. Federal and state are parallel systems on one stub.

Bottom line

Pub 15-T is the IRS playbook for how employers figure federal income tax withholding from Form W-4 and period wages using percentage and wage-bracket methods. It does not compute FICA, state tax, or your final Form 1040 bill. Keep your W-4 current, read stubs with gross vs net literacy, and use the current Publication 15-T, payroll software, or the IRS Tax Withholding Estimator for withholding estimates.