You cannot register, buy from, or partner with an Illinois company until you confirm it exists and sits in good standing. The free Illinois Business Entity Search, run by the Illinois Secretary of State (SOS), returns that answer in seconds for every registered corporation, LLC, and partnership in the state.
This guide shows you how to run the search, read the results, check name availability, and order the documents banks and states ask for. Every fee and label below is verified against the SOS’s own pages.
What Is the Illinois Business Entity Search?
The Illinois Business Entity Search is a free public lookup inside the Illinois Secretary of State’s Business Services department, often called the Illinois Business Services database. It confirms whether a business is registered in Illinois and shows its legal status, formation date, and registered agent. The database covers corporations, not-for-profit corporations, limited liability companies (LLCs), limited partnerships (LPs), and limited liability partnerships (LLPs).
| Detail | What the search offers | Source |
|---|---|---|
| Operator | Illinois Secretary of State, Business Services Department | ilsos.gov |
| Cost | Free | Illinois SOS Business Services |
| Entities covered | Corporations, not-for-profits, LPs, LLCs, LLPs | Illinois SOS Business Services |
| Search by | Name, keyword, partial word, file number, registered agent, officer, manager | apps.ilsos.gov search tool |
| Certificate of Good Standing | $25 (corporation or LLC), $5 (not-for-profit) | Illinois SOS Business Search page |
How Do I Search the Illinois Secretary of State Business Database?
Open the SOS Business Entity Search tool, enter a business name or file number, and review the matching records. The tool is free and needs no account. Illinois lets you search by name, keyword, partial word, file number, and even a registered agent or officer name. Results appear instantly on screen.
- Open the search tool at apps.ilsos.gov/businessentitysearch/.
- Choose a search method: business name, partial word, keyword, or file number.
- Type your term and run the search.
- Review the results list, which shows name, entity type, status, and file number.
- Click a record for detail: formation date, registered agent, and filing history.
Searches are limited to individual, non-bulk lookups, per the SOS tool.
How Do I Check If a Business Name Is Taken in Illinois?
Search the database for your exact and partial name. If no identical or confusingly similar entity appears, the name is likely available, subject to the SOS’s distinguishability rules. A clear search is not a guarantee, because the Secretary of State makes the final call at filing.
Illinois requires a name to be “distinguishable upon the records” from existing corporation and LLC names, per 805 ILCS 5/4.05. Adding “corporation,” “company,” or “limited” does not by itself make a name distinguishable. To hold a name, file a name reservation (Form LLC-1.15) for $25, which reserves it for 90 days, per the SOS LLC fee schedule. Assumed names (doing-business-as, or DBA) register at the county level for sole proprietors and with the SOS for entities. You can also run a quick company name check before you file.
How Do I Search for an Illinois LLC or Corporation?
Use the same Business Entity Search for both. LLCs and corporations sit in one database but carry different compliance markers. Search by name or file number, then open the record to see status and filings.
What does an Illinois LLC search show?
An LLC record shows status, formation date, registered agent, and annual report standing. Every Illinois LLC owes a $75 annual report fee, and series LLCs add $50 per active series, per the SOS LLC fee schedule. Records also flag professional limited liability companies (PLLCs) and series designations, which matter for liability review.
What does an Illinois corporation search show?
A corporation record shows status, annual report standing, and franchise tax standing, which Illinois corporations remit with their annual report. Since January 1, 2026 the first $10,000 of franchise tax liability stays exempt, effective for reports due on or after January 1, 2025, per 805 ILCS 5/15.35. Corporation and LLC file numbers use distinct formats.
What Is an Illinois File Number (Entity ID)?
A file number is the unique ID the Illinois SOS assigns each corporation and LLC at formation. People call it the “entity ID,” but Illinois’s official term is “file number.” Corporations and LLCs use distinct number formats. Searching by file number returns a single exact-match record, which makes it the fastest way to confirm a specific entity.
What Does Active vs. Inactive Status Mean in Illinois?
Active, or good standing, means the entity is current on all required filings and fees. Any other status signals a lapse or a closure, from a missed annual report to voluntary or state-ordered dissolution. The table below maps each label the database returns and its usual cause.
| Status | What it means | Typical cause | Source |
|---|---|---|---|
| Active / Good Standing | Entity is current on all filings and fees | Reports filed, fees paid | Illinois SOS |
| Not in Good Standing | Behind on annual report or franchise tax, not yet dissolved | Missed report or fee | Illinois SOS |
| Dissolved (voluntary) | Owners closed the entity | Articles of dissolution filed | Illinois SOS |
| Administratively / Involuntarily Dissolved | State dissolved a domestic entity | Unfiled annual report or unpaid fee | 805 ILCS 180/35-25 |
| Revoked / Forfeited (foreign) | Foreign entity lost authority to transact | Non-filing or non-payment | Illinois SOS |
| Withdrawn | Foreign entity ceased operating in Illinois | Withdrawal filed | Illinois SOS |
What Does a Forfeited Business Status Mean in Illinois?
A forfeited status means the entity lost its authority to do business, usually for unfiled annual reports or unpaid fees. Illinois labels domestic entities “administratively dissolved” and foreign entities “revoked” or “forfeited.” The entity loses good standing, name protection, and standing to sue in Illinois courts until it is reinstated.
The SOS may administratively dissolve an LLC for failing to file its annual report and fee before its anniversary month, per 805 ILCS 180/35-25. For corporations, the SOS must mail a Notice of Delinquency and allow 90 days, or 30 days for certain grounds, to cure before dissolving, per 805 ILCS 5/12.40. Reinstatement requires filing all delinquent reports plus a $200 reinstatement fee, per the SOS fee schedule.
Can You Search by Registered Agent Name in Illinois?
Yes. The free Illinois Business Entity Search lets you search by registered agent name, plus president, secretary, and manager names, alongside business name and file number. Searches stay limited to individual, non-bulk lookups. Every Illinois entity must keep a registered agent with a physical Illinois address, and no P.O. boxes are allowed.
The record shows the current registered agent and office address, useful for service of process and due diligence. The search reflects only the current agent, not past ones.
What Does the Filing History Show in an Illinois Entity Search?
The record lists filed documents with dates: formation, amendments, annual reports, mergers, reinstatements, and dissolutions. The free view is a list. Certified or actual document copies require a paid order through the Business Services portal. Gaps in annual reports flag compliance risk during due diligence on a partner or acquisition target.
How Do I Get an Illinois Certificate of Good Standing?
Order it online through the SOS Business Services portal for a fee. A Certificate of Good Standing costs $25 for a corporation or LLC and $5 for a not-for-profit, per the SOS Business Search page. The free search shows status on screen. The certificate is the official document banks, lenders, and other states require for financing or foreign qualification.
How Much Do Illinois Business Search and Filing Fees Cost?
The search itself is free. Forming an entity, filing reports, and ordering documents carry fees set by the Illinois SOS. The table below lists current fees from the SOS LLC fee schedule and the corporation fee schedule.
| Item | Fee | Source |
|---|---|---|
| Business entity search | $0 (free) | Illinois SOS Business Services |
| Certificate of Good Standing (corporation or LLC) | $25 | Illinois SOS Business Search page |
| Certificate of Good Standing (not-for-profit) | $5 | Illinois SOS Business Search page |
| LLC Articles of Organization (Form LLC-5.5) | $150 | Illinois SOS LLC fee schedule |
| Series LLC Articles of Organization (Form LLC-5.5(S)) | $400 | Illinois SOS LLC fee schedule |
| Certificate of Designation, per series (Form LLC-37.40) | $50 | Illinois SOS LLC fee schedule |
| LLC annual report | $75 | Illinois SOS LLC fee schedule |
| LLC name reservation (Form LLC-1.15) | $25 (90 days) | Illinois SOS LLC fee schedule |
| LLC reinstatement (Form LLC-35.40) | $200 | Illinois SOS LLC fee schedule |
| Corporation Articles of Incorporation | $150 | Illinois SOS corporation instructions |
| Corporation annual report | $75 | Illinois SOS corporation fee schedule |
| Corporation reinstatement | $200 | Illinois SOS corporation fee schedule |
| Expedited 24-hour processing | +$100 | Illinois SOS LLC fee schedule |
How Do You Form a Series LLC in Illinois?
File Articles of Organization for a series LLC (Form LLC-5.5(S)) with the Illinois SOS for $400, more than double the $150 standard LLC fee, per the SOS LLC fee schedule. Illinois is one of a limited number of states that permit series LLCs, where each series holds separate assets, members, and its own liability shield.
Each individual series needs a Certificate of Designation (Form LLC-37.40) for $50, and each active series carries a $50 annual report surcharge, per the SOS fee schedule. Expedited 24-hour filing adds $100, bringing the series formation total to $500, per the SOS LLC instructions. Give each series its own operating agreement to keep the liability shields clean.
What Doesn’t the Illinois Business Entity Search Show?
The search does not show sole proprietorships, county-registered DBAs, trademarks, or pending filings. Sole proprietors and general partnerships register assumed names at the county level, so they never appear. Recently filed records may lag before showing, and a Certificate of Incorporation returned by the search holds no shareholder or ownership records.
If a search returns nothing for a business you expect to find, check spelling, drop special characters, and try a partial-word or keyword search. Remember that DBAs and sole proprietorships are not in the database at all.
What Should You Do After Your Illinois Entity Search?
Once your name clears, move to formation and compliance. Register the entity, reserve the name if you are not ready to file, run a trademark check, and calendar your recurring deadlines. These steps keep your new entity in good standing from day one.
- Register the entity by filing Articles of Organization or Articles of Incorporation.
- Reserve the name for 90 days ($25) if you plan to file later.
- Search the United States Patent and Trademark Office (USPTO) for federal trademark conflicts.
- Track your annual report and franchise tax dates with a compliance calendar.
How Commenda Simplifies Illinois Entity Management
An Illinois business entity search is a one-time snapshot. Keeping your entity in good standing is continuous work. Commenda’s entity management platform handles that from formation through fully managed entities, tracking every annual report, franchise tax filing, and registered agent update in one dashboard.
Forming a new company? Commenda’s incorporation service files your Illinois LLC or corporation correctly the first time. Check a name with the company name checker, and never miss a deadline with the compliance calendar. Book a demo for a walkthrough of keeping your Illinois entity in good standing automatically.
