Illinois nexus rules determine when an out-of-state business owes Illinois taxes, and they turn on two ideas: physical presence in the state and enough economic activity to cross a dollar threshold. For sales tax, the trigger as of January 1, 2026 is $100,000 or more in gross receipts from sales to Illinois purchasers over the preceding 12 months. For corporate income tax, physical presence controls, though a federal law shields some sellers of tangible goods. The old 200-transaction sales tax test is gone, and the state’s franchise tax was fully repealed on January 1, 2026.
The $100,000 Sales Tax Threshold
A remote seller triggers Illinois sales tax nexus when cumulative gross receipts from sales of tangible personal property to Illinois purchasers reach $100,000 during the preceding 12-month period. That single dollar test is now the entire economic nexus rule. The 200-transaction alternative that applied before 2026 no longer exists.1Illinois Department of Revenue. FY 2026-12, Destination-Based Retailers’ Occupation Tax Changes
You check the threshold quarterly, at the end of March, June, September, and December, looking back 12 months each time. Once you cross the line, you register, collect, and remit state and local Retailers’ Occupation Tax for one year, then reassess at the end of that year.2Illinois Department of Revenue. Retailers’ Occupation Tax
The $100,000 count includes all gross receipts from retail sales to Illinois purchasers, taxable or exempt. The state rate is 6.25%, and destination-based local taxes stack on top based on the purchaser’s address, so accurate address data matters. If you accidentally collect destination-based tax before you’ve crossed the threshold, either refund the customer or remit the amount to the Illinois Department of Revenue as Use Tax on Form ST-1, reporting anything above the 6.25% state rate as excess tax.1Illinois Department of Revenue. FY 2026-12, Destination-Based Retailers’ Occupation Tax Changes
Physical Presence Triggers for Sales Tax
Physical presence creates sales tax nexus regardless of the $100,000 figure. Owning or leasing property in Illinois, storing inventory in an Illinois warehouse or fulfillment center, and having employees working in the state all qualify. Third-party fulfillment services holding your goods in Illinois count too, which catches many e-commerce sellers using marketplace logistics networks without realizing their inventory sits in the state.
Trade shows have a specific safe harbor. Under Illinois administrative regulations, you avoid establishing physical presence nexus if you attend no more than two Illinois trade shows and spend no more than eight days total at those shows within a 12-month period. Cross either limit and the safe harbor disappears.3Legal Information Institute. Illinois Admin Code tit 86 150.802 – Trade Show Appearances
Temporary activities can also establish presence: a repair technician visiting customers or an independent contractor regularly soliciting sales may be enough. Illinois takes an expansive view, so evaluate any recurring in-state activity, not just permanent operations.
Marketplace Facilitators
Amazon, eBay, and similar platforms must collect and remit Retailers’ Occupation Tax on sales they facilitate into Illinois. Starting January 1, 2026, a marketplace facilitator is treated as the retailer once its combined gross receipts from its own sales and third-party sales through its platform reach $100,000 in the preceding 12-month period, checked quarterly.4Illinois General Assembly. Illinois Compiled Statutes 35 ILCS 105/2d
If you sell exclusively through a registered facilitator, you’re generally relieved of the collection obligation for those sales. Direct sales channels are separate. If your own direct sales to Illinois customers independently cross $100,000, you have your own registration and collection duty for those transactions.
Corporate Income Tax Nexus
Illinois imposes a corporate income tax at 7% plus a 2.5% personal property replacement tax, for a combined 9.5% rate. Income tax nexus arises from physical presence: an office, warehouse, or employees in the state. Even a single employee working remotely from an Illinois home can create nexus for the employer.
Employees regularly soliciting orders, doing administrative work, performing maintenance, or installing products all create a connection. So does storing replacement parts or performing engineering work in the state.
Once income tax nexus exists, Illinois apportions income using a single-sales-factor formula, weighting sales at 100%. Services and intangibles are sourced to where the customer receives the benefit. The return is Form IL-1120.5Legal Information Institute. Illinois Admin Code tit 86 100.3370
The P.L. 86-272 Shield and What Breaks It
Public Law 86-272 is a federal law that prevents states from imposing a net income tax on an out-of-state company whose only in-state activity is soliciting orders for tangible personal property, provided orders are approved outside the state and filled by shipment from outside the state.6Office of the Law Revision Counsel. 15 USC 381 – Imposition of Net Income Tax
The protection is narrow. Solicitation covers activities tied directly to requesting an order, like providing company vehicles to sales reps or training salespeople. Collecting delinquent accounts in Illinois, installing or repairing products, maintaining any facility, or providing post-sale technical support all push a company outside the safe harbor.7Multistate Tax Commission. Statement of Information Concerning Practices Under Public Law 86-272
P.L. 86-272 also covers only tangible personal property. Services, software licenses, digital goods, and other intangibles fall outside it entirely. Companies selling a mix should evaluate whether the non-tangible sales activities independently create nexus.
Internet Activities That Defeat Protection
Illinois follows the Multistate Tax Commission’s 2021 guidance, which drew sharp lines around digital business practices. Placing cookies on Illinois customers’ devices that gather search data used to adjust production schedules, develop new products, or identify new items to sell defeats P.L. 86-272 immunity. So does providing post-sale customer assistance via live chat or email initiated from the company’s website.8Multistate Tax Commission. Statement of Information Concerning Practices Under Public Law 86-272 – Internet Activity
Cookies that only remember cart contents, store login information, or remind customers of previously viewed products are considered ancillary to solicitation and preserve the shield. A static FAQ page also stays protected. The test is whether the digital activity does more than help the customer place an order.8Multistate Tax Commission. Statement of Information Concerning Practices Under Public Law 86-272 – Internet Activity
Many e-commerce businesses lose protection here without realizing it. Running a chatbot that answers post-sale product questions for Illinois customers can be enough. If your website does anything interactive beyond facilitating the order itself, assume the protection is gone.
Software and Digital Goods
Illinois taxes retail sales of pre-written (canned) software regardless of delivery method, including electronic downloads. Packaged or downloadable software sold to Illinois customers is tangible personal property subject to the Retailers’ Occupation Tax.9Illinois Department of Revenue. Is Computer Software Taxable?
Software as a service is grayer. Illinois has generally treated true SaaS, where the customer accesses software remotely without downloading it, differently from canned software, and the classification depends on the transaction. Custom software written for a single customer is typically not taxable. Evaluate each cloud-based product individually, because the line between taxable canned software and non-taxable services shifts with delivery method and degree of customization.
Franchise Tax: No Longer Applies
Illinois fully repealed its corporate franchise tax effective January 1, 2026. No payments have been required since January 1, 2025, and there are no refunds or prorations for any franchise tax that would have been due on or after that date.10Illinois General Assembly. HB5490 103rd General Assembly – Franchise Tax Repeal
If you’re working from older Illinois compliance checklists, remove franchise tax from the list. The obligation based on paid-in capital apportioned to Illinois no longer exists.
Penalties and Interest
Illinois penalties escalate with time and with how the state finds out. Late-filing penalties come in two tiers. The initial penalty is the lesser of $250 or 2% of the tax due (reduced by timely payments). If you still haven’t filed within 30 days of an IDOR nonfiling notice, an additional penalty applies equal to the greater of $250 or 2% of the tax shown due, capped at $5,000.11Illinois Department of Revenue. Pub-103, Penalties and Interest for Illinois Taxes
Late-payment penalties are steeper. One to 30 days late is 2%. After 30 days it jumps to 10%. If IDOR finds the underpayment through an audit rather than your own correction, the penalty rises to 15%. If you don’t pay within 30 days after the audit’s final assessment, it goes to 20%.11Illinois Department of Revenue. Pub-103, Penalties and Interest for Illinois Taxes
Unpaid tax also accrues interest at 7% annually through at least June 30, 2026.12Illinois Department of Revenue. Interest Rates
Voluntary Disclosure If You’re Already Behind
If you’ve been selling into Illinois without registering, a voluntary disclosure agreement is the best way to limit exposure. Illinois’s Voluntary Disclosure Program caps the look-back at four years and waives all penalties if you pay the tax and interest within 60 days of being billed. Any audit is also limited to the approved four-year period.13Illinois Department of Revenue. Voluntary Disclosure Program
You apply by submitting Form BOA-2 to IDOR’s Problems Resolution Division and registering through MyTax Illinois or with a completed Form REG-1. If someone else is handling the process, include Form IL-2848 (Power of Attorney).13Illinois Department of Revenue. Voluntary Disclosure Program
There’s a hard disqualifier. If IDOR has already contacted you about the tax type in question, you cannot use the program for that tax type. Contact includes an inquiry, a filed return, or any payment of that tax. That’s the reason to act before a notice arrives.14Multistate Tax Commission. Multistate Voluntary Disclosure Program
The gap between disclosure and audit is large. With a voluntary agreement you pay four years of back tax plus interest and no penalties. Without one you face the full statute of limitations, penalties up to 20%, and the same interest.
Registering and Buying an Illinois Business
Registration runs through MyTax Illinois at mytax.illinois.gov. Select “Register a New Business (Form REG-1)” to set up Retailers’ Occupation Tax, corporate income tax, and other accounts. Electronic submissions process in roughly one to two business days.15Illinois Department of Revenue. Business Registration
Have your legal name, organizational structure, Federal Employer Identification Number, and the date nexus was first established. Registration generates an Illinois Account ID along with your filing frequency and due dates. Sales tax accounts are assigned monthly, quarterly, or annual schedules based on anticipated liability.16Illinois Department of Revenue. What Is MyTax Illinois and How Do I Access It?
If you’re acquiring an Illinois business or its assets, unpaid tax liabilities can follow the sale. Illinois requires buyers to file Form CBS-1 (Notice of Sale, Purchase, or Transfer of Business Assets) before closing. Failing to file makes the purchaser personally liable for the seller’s unpaid taxes up to the reasonable value of the acquired property. IDOR issues a bulk sales release only after all taxes, penalties, and interest are cleared.17Illinois Department of Revenue. Instructions for Form CBS-1, Notice of Sale, Purchase, or Transfer of Business Assets
This applies to asset purchases and stock acquisitions, and contractual language between buyer and seller doesn’t override the state’s claim. Request a tax clearance before closing to avoid inheriting the seller’s tax debt.