Illinois Sales Tax Due Dates — 2026
Exact Illinois sales tax filing deadlines for 2026 and 2027 — every period, already adjusted for weekends and holidays. Find your filing frequency, see the dates, and add them to your calendar.
Illinois Monthly Sales Tax Due Dates — 2026
| Filing period | Due date |
|---|---|
| December 2025 | Tue, January 20, 2026 |
| January 2026 | Fri, February 20, 2026 |
| February 2026 | Fri, March 20, 2026 |
| March 2026 | Mon, April 20, 2026 |
| April 2026 | Wed, May 20, 2026 |
| May 2026 | Mon, June 22, 2026moved off weekend/holiday |
| June 2026 | Mon, July 20, 2026 |
| July 2026 | Thu, August 20, 2026 |
| August 2026 | Mon, September 21, 2026moved off weekend/holiday |
| September 2026 | Tue, October 20, 2026 |
| October 2026 | Fri, November 20, 2026 |
| November 2026 | Mon, December 21, 2026moved off weekend/holiday |
Dates are adjusted for weekends and U.S. federal holidays. Some states observe additional state holidays — always confirm the exact date with the Illinois Department of Revenue.
How Illinois assigns your filing frequency
Your frequency is based on how much sales tax you collect. Illinois Department of Revenue notifies you of your assigned schedule.
Annual
Very small sellers (average liability of $50/month or less).
Quarterly
Sellers with average monthly liability between $50 and $200.
Monthly
Sellers with average monthly liability over $200.
Illinois sales tax filing rules
Good to know
Larger filers may also owe quarter-monthly (accelerated) payments.
Timely-filing discount
Retailer's discount of 1.75% of tax collected, for timely filers (capped at $1,000/year).
Filing Illinois sales tax late
Illinois charges a late-filing and late-payment penalty plus interest on any unpaid tax, and most states apply a minimum penalty even on a zero return. Filing late also forfeits the timely-filing discount described above. File on time — even a return with no tax due must be filed. Confirm current penalty amounts with the Illinois Department of Revenue.
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Frequently Asked Questions
Official sources
Last verified 2026-05-30 against state revenue references. This page is for general information, not tax advice — confirm your specific due dates with the Illinois Department of Revenue.
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