Sales Tax Nexus Rules in Illinois: Thresholds, Requirements, and CPA Action Steps

Economic nexus threshold (current, verified 2026-06-16): $100,000 in gross receipts; the 200-transaction prong was repealed effective Jan 1, 2026 (note destination-sourced State + local ROT for remote retailers).

Introduction

Illinois applies economic nexus rules alongside complex local tax administration and sourcing rules. For CPA firms, Illinois requires careful analysis of revenue thresholds, marketplace rules, and origin versus destination sourcing.

What Creates Sales Tax Nexus in Illinois?

Physical Nexus

• Offices, warehouses, inventory

• Employees or contractors

• Fulfillment centers

Economic Nexus

Remote sellers may establish nexus without physical presence.

Marketplace Nexus

Marketplace facilitators collect and remit tax for marketplace sales.

Economic Nexus Thresholds in Illinois

A seller establishes economic nexus with $100,000 or more in Illinois sales in the previous 12-month period. Illinois is revenue-only — there is no 200-transaction threshold. The 200-transaction prong was repealed effective January 1, 2026 (HB 2755). Illinois measures cumulative gross receipts over the prior 12 months, assessed quarterly.

Does Illinois Impose Sales Tax?

Yes. Illinois imposes:

• State sales tax

• Local sales taxes

Illinois uses destination-based sourcing for remote sellers.

Registration Requirements

Registration is completed with the Illinois Department of Revenue.

• Required once nexus is established

• Marketplace sellers may still need registration for direct sales

Filing Frequency and Due Dates

• Monthly filing is typical

• Returns due by the 20th of the following month

Penalties and Interest

• Late filing and late payment penalties

• Interest accrues from original due date

CPA Action Steps

1. Track rolling 12-month sales and transactions

2. Identify physical presence and inventory

3. Review marketplace coverage

4. Register promptly

5. Monitor sourcing and rate application

Common CPA Mistakes

• Misapplying sourcing rules

• Ignoring transaction thresholds

FAQs

Does Illinois use destination sourcing?
Yes, for remote sellers.

Are exempt sales included?
Yes.

Conclusion

Illinois nexus compliance demands disciplined threshold monitoring and accurate sourcing analysis.