Illinois Payroll Taxes: 2026 Employer Guide
Quick Facts
Key payroll tax details at a glance.
State Income Tax
Flat (up to 4.95%)
SUI New Employer Rate
3.35% (3.45% for certain industries)
SUI Wage Base
$14,250 per employee
SUI Rate Range
0.75% to 7.05%
Employee SUI Contribution
No
Local Taxes
No
Overview: Illinois Payroll Landscape
Illinois keeps its income tax simple with a flat 4.95% rate, but the state's payroll environment has a few quirks. The SUI new employer rate varies by NAICS code, with certain industries like administrative support paying a higher starting rate. Illinois requires its own IL-W-4 withholding form and has a moderate SUI wage base of $14,250.
Illinois has reciprocity agreements with Iowa, Kentucky, Michigan, and Wisconsin. The state does not have local income taxes at the employee level. This guide covers everything you need to stay compliant.
Illinois State Income Tax
Withholding rates, brackets, and forms.
Tax Type
Flat
Top Rate
4.95%
Withholding Form
IL-W-4
Illinois Unemployment Insurance (SUI)
Employer rates, wage bases, and contribution details.
New Employer Rate
3.35% (3.45% for certain industries)
Wage Base
$14,250 per employee
Rate Range
0.75% to 7.05%
Employee Contribution
—
Illinois SUI (State Unemployment Insurance) is an employer-paid tax that funds unemployment benefits for workers who lose their jobs. It is administered by the Illinois Department of Employment Security (IDES). Registration: Employers must register with the Illinois Department of Employment Security (IDES) as soon as they hire their first Illinois employee. Registration can be completed online.
Illinois Compliance Checklist
Deadlines, filing requirements, and official resources.
Key Deadlines
Withholding deposits
Due Varies by liability
Quarterly returns (Q1)
Due April 30
Quarterly returns (Q2)
Due July 31
Quarterly returns (Q3)
Due October 31
Quarterly returns (Q4)
Due January 31
Annual reconciliation
Due February 28
W-2 state copies
Due January 31
New hire report
Due Within 20 days of start date
How Warp Handles Illinois Payroll
Warp is the only AI-native HR & Payroll platform built for ambitious companies. Instead of clicking through clunky dashboards or Illinois's .gov websites for taxes, Warp's AI agents open your Illinois tax accounts, file every payroll form, and resolve every tax notice automatically.
- Illinois tax account registration and setup
- Automated income tax withholding calculations and deposits
- SUI registration and quarterly filings
- Annual W-2 and reconciliation filing
- Tax notice resolution directly with Illinois agencies, so you never spend hours on hold
Every Warp customer gets a dedicated Account Manager and Benefits Advisor included to guide them through payroll setup, multi-state expansion, and benefits selection.
If you don't want to deal with navigating Illinois .gov portals, check out a demo of Warp to see how we can help you stop worrying about compliance and get back to building.
Tax data last verified: March 12, 2026