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Illinois Income & Sales Tax for eCommerce Businesses

Illinois is the third-largest state economy in the U.S. and home to Chicago — one of the most significant consumer markets for eCommerce sellers. It also has one of the highest corporate income tax rates in the country and recently enacted sweeping tax changes that took effect January 1, 2026. If you sell into Illinois, this guide is essential reading. At Tall Oak Advisors, we've been tracking these legislative changes closely so our clients aren't caught off guard.

3 min

Table of contents

Illinois Income & Tax for eCommerce Businesses

💡 2026 UPDATE: Illinois eliminated its 200-transaction economic nexus threshold as of January 1, 2026 (H.B. 2755, signed June 2025). Economic nexus for sales tax is now based solely on the $100,000 gross receipts threshold. Low-volume, high-ticket sellers who previously avoided nexus because of the transaction count are now potentially exposed.

Part 1: Illinois Corporate Income Tax

Illinois imposes a flat 9.5% combined corporate income tax rate on C corporations — one of the highest in the nation. This breaks down as:

  • 7.0% Illinois Corporate Income Tax (IITA)

  • 2.5% Personal Property Replacement Tax (PPRT) — a separate levy that effectively adds to the total burden for corporations

For pass-through entities like S corporations and partnerships, the PPRT rate is 1.5%, and the income passes through to individual partners/shareholders who pay Illinois personal income tax at a flat rate of 4.95%.

Who Has Illinois Corporate Income Tax Nexus?

Nexus is established through physical presence or economic activity in Illinois:

  • Owning or leasing property in Illinois, including FBA inventory in Amazon fulfillment centers

  • Having employees, agents, or representatives performing services in Illinois

  • Maintaining an office, warehouse, or distribution center in the state

  • Remote employees working from an Illinois address create both employment tax nexus and potential income tax nexus

PL 86-272 Protections

Federal Public Law 86-272 protects C corporations from Illinois income tax if their only in-state activity is soliciting orders for tangible goods shipped from outside Illinois. However, any activity beyond pure order solicitation — including FBA inventory storage — can eliminate this protection. The law does not apply to sales tax obligations.

Part 2: Illinois Sales Tax — 2026 Threshold Changes

For most eCommerce sellers, Illinois's sales and use tax is the primary concern. Illinois uses a hybrid sourcing model: in-state sellers pay at the origin rate; remote sellers (those without physical presence) collect at the destination rate.

Economic Nexus — New 2026 Rule

Effective January 1, 2026, the economic nexus threshold is now:

  • $100,000 in gross receipts from Illinois customers in the prior 12-month period (rolling)

  • The 200-transaction threshold has been permanently eliminated as of January 1, 2026

  • Gross receipts include taxable and exempt sales; marketplace sales through certified facilitators are excluded from the individual seller's threshold

Illinois Sales Tax Rate

The state base rate is 6.25% on general merchandise. Local jurisdictions can add additional amounts, with combined rates reaching up to 11.0% in some areas of Chicago. This makes Illinois one of the most complex local tax environments in the country for remote sellers.

FBA Sellers: Immediate Physical Nexus

Amazon operates major fulfillment centers in the Chicago metropolitan area and elsewhere in Illinois. If you use FBA, your inventory is physically present in Illinois — creating immediate physical nexus regardless of your revenue level. This triggers both sales tax and, for C corporations, potential income tax exposure.

The 2025 Amnesty Program

Illinois offered a general tax amnesty program from October 1 to November 15, 2025, covering liabilities from July 1, 2018 through June 30, 2025. If you had unresolved prior-period exposure and did not take advantage of this program, a voluntary disclosure conversation with a tax advisor is still advisable to limit lookback periods and penalty exposure going forward.

What About Sales Tax?

Illinois's combined rates — up to 11% in Chicago — combined with its hybrid origin/destination sourcing rules, make it one of the most technically complex states for eCommerce sales tax compliance.

At Tall Oak Advisors, we put together this guide as a resource for our eCommerce community. Tax rules vary significantly from state to state, and we want sellers to have the information they need to make informed decisions. More info at talloakadvisors.com

Disclaimer: The information in this article is for general informational purposes only and does not constitute legal or tax advice. Tax laws change frequently. Consult a qualified tax advisor or CPA regarding your specific situation.

Sources: Illinois Income Tax Act (IITA); Illinois Retailers' Occupation Tax Act; H.B. 2755 (June 2025); IL Dept. of Revenue; Pub. L. No. 86-272; Tax Foundation 2026 State Tax Changes.

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