Illinois Sales Tax Hike Effective August 1, 2026: What Cook, DuPage, Kane, Lake, McHenry and Will County Businesses Need to Know

Maria Gordon

CPA | Tax Manager

Beginning August 1, 2026, local sales tax rates in some Illinois counties will increase by 0.25%. Retailers and servicepersons making taxable sales in Cook, DuPage, Kane, Lake, McHenry, or Will counties must increase their local sales tax rate by 0.25%. The increase is to the Northern Illinois Transit Authority (NITA) portion of sales tax collected in these counties.

How Will I Know My Updated Rate?

The new rate will appear on your Illinois sales/use tax Form ST-1 when your business electronically files on MyTax Illinois. You may also find your updated rate using the MyTax Illinois Tax Rate Finder. Select “August 2026” rates to look up the exact rate for your business address.

What to Do Before August 1, 2026

To stay compliant and avoid under-collecting sales tax, businesses in the affected counties should complete these steps before the effective date:

• Verify your new tax rate using the MyTax Illinois Tax Rate Finder
• Update your systems to reflect the new rate where applicable

How to Report Sales Made Before August 1, 2026

If a sale was made prior to August 1, 2026, and was properly taxed at the prior (lower) rate, report it on Line 8a of Form ST-1 or ST-2. Note – line 8a may only be used for sales properly subject to a different rate.

Need Help Preparing for This Change?

Getting ahead of this update now ensures your business collects the correct sales tax from day one. The new tax will be in effect August 1, regardless of whether your business makes the change in your system. Cray Kaiser is here to help if you have any questions about how this change affects your business or need assistance updating your systems.