What is Circular E?
Circular E, officially known as IRS Publication 15, is the federal guide employers use to understand and fulfil their tax withholding and payroll responsibilities. It provides step-by-step instructions on how to calculate and withhold federal income tax, Social Security, and Medicare taxes from employee wages, and how to deposit and report those taxes to the IRS.
If you're running a small business and managing payroll, Circular E is one of the most important IRS publications to keep in your toolbox. It gets updated annually and is especially helpful when onboarding new employees, adjusting for mid-year tax changes, or verifying your payroll system’s compliance.
Why Circular E matters for employers
As an employer, you're responsible for correctly withholding and submitting employment taxes. Circular E helps you:
- Determine how much federal income tax to withhold from each employee’s paycheck
- Apply the correct rates for Social Security and Medicare taxes
- Understand depositing schedules for federal tax payments
- File Form 941 (Employer’s Quarterly Federal Tax Return) accurately
- Stay compliant with IRS rules and avoid costly fines or penalties
The guide includes charts, tables, and examples to walk you through each step—even if you’re new to payroll.
What’s included in Circular E?
Here’s what you’ll find in a typical edition of Publication 15:
- Wage bracket and percentage method withholding tables
- Federal income tax withholding instructions
- Withholding rules for supplemental wages (like bonuses or commissions)
- Instructions for depositing taxes electronically using the Electronic Federal Tax Payment System (EFTPS)
- Form W-4 guidance for processing new hire information
- Rules for fringe benefits, sick pay, and employee tips
- Overview of penalties for late deposits or incorrect filings
It also explains how to treat different types of workers, like statutory employees or nonresident aliens, for tax purposes.
Where to find Circular E
You can access the most current version of Circular E on the IRS website. Make sure to download the version for the current tax year, as tables and rates are updated annually.
Circular E vs. other IRS publications
While Circular E (Publication 15) is the primary reference for most employers, the IRS also publishes:
- Publication 15-T – Includes detailed tax tables for more precise withholding calculations
- Publication 15-A – Offers more in-depth information on fringe benefits, sick pay, and employee classifications
- Publication 505 – Focused on individual tax withholding and estimated taxes
For most small businesses, Circular E is the go-to resource, but occasionally you’ll need to cross-reference these related guides.
How to use Circular E in everyday payroll
Here’s how a typical business owner or payroll manager might use Circular E:
- Onboard a new employee – Use the employee’s W-4 form and Circular E’s tax tables to determine the correct withholding.
- Run payroll – Calculate each employee’s federal income tax, Social Security, and Medicare deductions based on current guidance.
- Make tax deposits – Follow the deposit schedule outlined in Circular E to stay on time.
- Prepare quarterly filings – Use it as a reference when completing Form 941.
- Handle unique pay situations – Refer to the publication for handling bonuses, retro pay, or fringe benefits.
Using Circular E regularly helps ensure you're not over- or under-withholding and keeps your business in the IRS’s good graces.
How Homebase helps streamline payroll and compliance
While Circular E is essential for understanding the rules, interpreting IRS tables and filing tax forms manually can get complicated fast. That’s where Homebase payroll makes life easier.
Homebase automatically:
- Calculates federal, state, and local tax withholdings based on Circular E guidelines
- Generates pay stubs with clear tax breakdowns
- Files payroll taxes and forms like 941 and W-2s on your behalf
- Sends tax payments electronically through EFTPS
- Updates rates and rules as tax laws change, so you’re always in compliance
Explore Homebase payroll to take the guesswork out of tax withholding and keep your payroll process clean, compliant, and stress-free.