Sellers often follow a short routine from the first sale to the filed return. The Till-to-Return Relay below is one general version, built from Illinois Department of Revenue (IDOR) material, and it is not advice for any one business. The overview and rules and numbers pages explain the details.
The Till-to-Return Relay
- Register with IDOR before selling, leasing or hiring.
- Look up the combined rate for each address in IDOR's Tax Rate Finder, and recheck after each 1 January, 1 July or mid-year change.
- Collect tax at that rate, and keep general merchandise, groceries and drugs apart in the books.
- For resale sales, take a Certificate of Resale (Form CRT-61), confirm the buyer's account ID is active and keep the certificate at least 3.5 years.
- File Form ST-1 by the 20th of the month after the period, electronically once annual gross receipts average $20,000 or more.
- Remote sellers retest the $100,000 mark at each quarter-end and keep destination location data.
- Report use tax on purchases made without Illinois tax (Form ST-44, or Form ST-1 for registered sellers), and tie ST-1 receipts to the general ledger.
Common mistakes
- Accepting a resale claim without checking that the buyer's Illinois account ID is active. IDOR will not accept a bare statement of resale.
- Treating Form CRT-61 as an all-purpose exemption certificate. It documents resale only.
- Letting blanket certificates go stale. IDOR says to update them at least every 3 years.
- Using an old combined rate after a 1 January, 1 July or 1 August change.
- Reporting groceries on pre-2026 lines of Form ST-1.
- Remote sellers assuming the 200-transaction test still applies, or skipping destination location data, which risks the 15% undetermined-location rate.
- Losing the vendor's discount by filing or paying late on an account that must e-file.
- Selling or leasing goods before registering.
When to talk to an attorney
A CPA cannot answer legal questions like these. They call for an attorney:
- A Notice of Tax Liability or personal-liability notice, or any petition to the Tax Tribunal or a circuit court.
- Possible criminal exposure, such as unfiled or false returns.
- A sale, purchase or restructuring of a retail business.
- A multi-state seller deciding whether to join the amnesty, which ends 31 October 2026, and how far back the exposure runs.
- Contract language that shifts sales tax between parties, or marketplace-facilitator agreements.
Frequently asked questions
Is there sales tax on groceries in Illinois in 2026?
The State 1% grocery tax ended on 1 January 2026. Local governments may charge their own 1% by ordinance, and the transit-district grocery tax continues. Candy, soft drinks and prepared food stay at the general rate. In IDOR's 1 August 2026 grocery file, Chicago and Cook show 1.50%, and Naperville and Aurora (Kane, Will and DuPage parts) show 2.00%. Address-level rates can differ.
Do out-of-state sellers have to collect Illinois sales tax?
A seller with a physical presence in Illinois is covered like an Illinois retailer. A remote seller or marketplace facilitator is covered from 1 January 2026 once Illinois gross receipts reach $100,000 in the look-back 12 months. The old 200-transaction test ended on 31 December 2025.
Is Form CRT-61 an exemption certificate?
No. It is a resale certificate. Exempt buyers such as qualifying nonprofits use an IDOR-issued exemption number instead.
Does Illinois tax services?
Illinois does not tax sales of service. It taxes the goods transferred during a service under the Service Occupation Tax, and it has taxed leases of goods since 1 January 2025.
A CPA can help with the payroll, tax and accounting side of these rules and works alongside the owner's attorney. Our sales tax service, the remote-retailer amnesty update, the Illinois Income Tax Act page and our Illinois state guide may also help.
Official sources
- Illinois Department of Revenue: Retailers' Occupation Tax
- Illinois Department of Revenue: Form CRT-61 instructions
- Illinois Department of Revenue: Bulletin FY 2026-03, grocery tax changes
- Illinois Department of Revenue: Questions and answers on service occupation tax
This page is a plain-language summary. The official source controls if there is any difference.