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2026 Payroll Withholding Model: Federal and Illinois – Excel XLSX
Excel (XLSX) + Zip archive file (ZIP)
BENEFITS OF THIS DOWNLOADABLE EXCEL DOCUMENT
- Traces every figure back to the IRS table it came from, through a 4,375-row verification log that names the source document, page and date for each one.
- Calculates federal withholding, Social Security with the wage base prorated across the period in which it is crossed, Medicare with the 0.9% surcharge, FUTA, and Illinois state withholding.
- Leaves every formula visible and every cell unlocked, so a reviewer can check the arithmetic instead of taking it on trust.
COMPENSATION EXCEL DESCRIPTION
WHAT THIS IS
A payroll withholding model for US employers, built as a spreadsheet and shipped together with the calculation engine and the test suite that prove its figures. Nine tabs, 912 formulas, no macros and no add-ins. Every formula is visible and every cell is unlocked, so any figure can be traced back to the table it came from.
It implements the percentage method of IRS Publication 15-T (2026), Worksheet 1A, with rates from Publication 15 (2026) and from each state revenue department's own published schedules.
WHY A REVIEWER CAN TRUST THE NUMBERS
Most payroll templates ask you to take the tables on faith. This one ships the audit.
A verification log of 4,375 rows accompanies the model. Each row carries its input, the published value, the calculated value, the result, and the source document with page and date.
4,350 of those rows reproduce, to the dollar, the Wage Bracket Method Tables published by the IRS in Publication 15-T (2026) – 725 wage intervals across six combinations of filing status and Step 2 checkbox. A further 3 rows check Worksheet 1A itself, 7 check federal constants read in Publication 15 (2026), and 15 check state figures read on each state's own revenue site. Every row returns Match.
You do not have to take that on faith either. The Python engine that generated the log ships with the model, together with four test suites you can run yourself:
The federal suite reproduces all 4,350 IRS cells and checks the Worksheet 1A edge cases, the Social Security wage base crossed part-way through a pay period, the 0.9% Additional Medicare surcharge and FUTA.
The state suite checks both of the worked examples printed in Illinois Booklet IL-700-T (2026) and the states that withhold without levying an income tax.
The parity suite opens the workbook itself, recalculates it through LibreOffice and compares every figure against the engine, to the cent. It also rebuilds a full year of 26 payments and requires the annual Social Security total to land exactly on $184,500 x 6.2%.
The year-over-year suite holds a signed snapshot of every constant and fails deliberately when the tax year changes, listing everything that needs reconfirming.
The output of the last run of each suite is included, so you can compare your run against ours.
WHAT THE MODEL CALCULATES
Federal income tax by the percentage method, Publication 15-T (2026) Worksheet 1A, including the Step 2 checkbox and pre-2020 Forms W-4.
Social Security at 6.2% to the 2026 wage base, prorated across the pay period in which the base is crossed rather than applied all or nothing.
Medicare at 1.45%, plus the 0.9% Additional Medicare surcharge above $200,000 year to date.
FUTA at 6.0% on the first $7,000, with the state credit.
Illinois income tax, and nine states that levy none: Texas, Florida, Tennessee, Nevada, South Dakota, Wyoming, New Hampshire, Alaska and Washington.
A printable one-page pay stub carrying year-to-date figures.
A quarterly summary laid out for Form 941, employer share included.
SCOPE – READ BEFORE BUYING
This edition calculates state income tax for Illinois only. It does not calculate state income tax for California, New York, Pennsylvania, Ohio, or the other 36 states that levy one. It does not handle local or municipal payroll taxes. Where a state is not supported, the model says so rather than returning a figure.
"No state income tax" is not the same as "no state withholding". Washington withholds Paid Family and Medical Leave and WA Cares; Alaska withholds unemployment insurance from the employee. Both are handled. The State Rules tab carries the source for every rate.
WHAT IS IN THE DOWNLOAD
The workbook itself, nine tabs and 912 formulas. Alongside it, a verification pack holding the 4,375-row verification log, a four-page start guide, the Python engine with its four test suites, and the recorded output of the last run of each one.
The workbook works in Microsoft Excel 2016 or later, Microsoft 365, and LibreOffice Calc. No macros, no add-ins, no subscription. Google Sheets is not supported. Running the test suites needs Python 3, and the parity suite also needs LibreOffice.
INTENDED USER
Bookkeepers, accountants and finance teams running payroll for a small US employer in a supported state, and reviewers who need to see how a figure was reached rather than be told that it is correct.
NOT TAX ADVICE
This is a calculation tool sold by an independent software author – not a CPA, not an enrolled agent, not an attorney. It is not affiliated with, endorsed by, or approved by the IRS, the U.S. Department of the Treasury, or any state revenue department, and nothing in it is tax, legal or accounting advice.
Payroll rules change during the year and agencies issue corrections. Verify every figure against the current official publications before you deposit or file anything. You remain responsible for your filings. Rates were checked on 11 August 2026 and the sources are named in the Sources and Verification tab.
Got a question about the product? Email us at support@flevy.com or ask the author directly by using the "Ask the Author a Question" form. If you cannot view the preview above this document description, go here to view the large preview instead.
Source: Best Practices in Compensation, Tax Excel: 2026 Payroll Withholding Model: Federal and Illinois Excel (XLSX) Spreadsheet, g63071269e20
