Illinois Quarterly Tax Calculator
Calculate your estimated quarterly tax payments for federal and Illinois state taxes. Designed for self-employed individuals, freelancers, and independent contractors.
IL State Tax: Flat 5.0%
Quarterly Payment Amount
$6,513
Per quarter (4 remaining)
Annual Tax Breakdown
2026 Payment Schedule
Jan 1 - Mar 31
Due: April 15, 2026
$6,513
Apr 1 - May 31
Due: June 15, 2026
$6,513
Jun 1 - Aug 31
Due: September 15, 2026
$6,513
Sep 1 - Dec 31
Due: January 15, 2027
$6,513
Don't miss your quarterly payments!
The IRS may charge penalties and interest if you underpay or pay late. Consider setting up automatic payments or calendar reminders.
Illinois Quarterly Tax Highlights
Illinois has a flat 4.95% income tax rate
Constitutional amendment requires flat rate
Use Form IL-1040-ES for quarterly payments
Simple flat rate for all income levels
Illinois Quarterly Tax FAQ
What is Illinois's income tax rate?
Illinois has a flat 4.95% income tax rate mandated by the state constitution. This applies equally to all income levels, making tax calculation straightforward.
Official References
This calculator uses current federal and Illinois tax rates and schedules:
- IRS Estimated Tax Guidelines
Federal quarterly tax requirements and Form 1040-ES
- Illinois Department of Revenue
Official Illinois tax authority
- IRS Self-Employment Tax
Social Security and Medicare tax information
This calculator provides estimates based on 2026 tax rates. Your actual tax liability may vary based on deductions, credits, and other factors. Consult a tax professional for personalized advice.