How to Check Business Name Availability in Illinois

To check business name availability in Illinois, run your proposed name through the Secretary of State’s free Business Entity Search at apps.ilsos.gov. The search takes about 30 seconds and covers corporations, not-for-profit corporations, limited partnerships, LLCs, and LLPs in a single database.¹ A clean result there is the first hurdle, not the last one: federal trademarks and domain names are separate checks, and skipping them is how people end up rebranding a year in.

Running the Secretary of State Search

Open the Business Entity Search page, enter your proposed name, and select “Business Name” as the search method. The tool also supports keyword and partial-word searches, which help catch similar names you might not think to look for.¹

Search several variations, not just your exact preferred name. If you’re set on “Lakeside Brewing Company,” also try “Lakeside Brew” and “Lakeside Beer.” Illinois applies a “distinguishable upon the records” standard that reaches beyond identical matches, so catching a near-conflict now is easier than arguing about it after you’ve paid a filing fee.

If the search returns no matching records, the name is likely available to register. If it returns active entities with the same or a similar name, move on to your backup options.

What “Distinguishable” Actually Means

Every name filed in Illinois must be distinguishable from all other names already on the Secretary of State’s records. For corporations, the standard comes from 805 ILCS 5/4.05, which measures a proposed name against all existing domestic and foreign corporations, LLCs, and reserved names.² LLCs face the same standard under 805 ILCS 180/1-10, checked against every entity type on record.³

The Secretary of State makes the final call, and the statute is clear that superficial tweaks won’t get you past an existing name. Under 805 ILCS 5/4.05(b), a proposed name is not distinguishable from an existing one solely because it differs in these ways:²

Swapping or adding entity designators such as “Corporation,” “Company,” “Incorporated,” “Limited,” or “Limited Liability.” “Midwest Supply LLC” and “Midwest Supply Inc.” conflict.
Changing articles or conjunctions (“the” to “a”), switching singular to plural, using a contraction, or changing verb tense. “The Green Door” and “Green Doors” are treated as the same name.

The list is not exhaustive. The Secretary of State can reject other cosmetic variations that don’t meaningfully set two names apart. If the only difference between your name and an existing one is a minor grammatical change, plan on a rejection.

Words That Trigger Extra Approvals

Some words are restricted regardless of whether the name is otherwise available. For corporations, the name cannot suggest the business conducts insurance, assurance, indemnity, or savings deposit activities. “Bank,” “banker,” and “banking” can appear only if the corporation has complied with Section 46 of the Illinois Banking Act. Words implying a corporate fiduciary role require permission from the Secretary of Financial and Professional Regulation under the Corporate Fiduciary Act.²

LLCs face the same category of restrictions. “Trust,” “trustee,” and “fiduciary” require compliance with the Corporate Fiduciary Act. Any LLC name using a word restricted by another Illinois statute has to satisfy that statute before the Secretary of State will accept the filing.³ If any of these words appear in your name, build time for the outside approval into your schedule before you file.

Reserving the Name Once You Find One

If the name is available but you’re not ready to file formation documents, you can reserve it. Corporations file Form BCA 4.10 with a $25 fee.⁴ LLCs file Form LLC-1.15.⁵ Either can be filed online or mailed to Springfield.

A reservation locks the name for 90 days. During that window, no one else can register a name that isn’t distinguishable from yours.⁶ Neither the corporate nor the LLC statute allows renewal. If the 90 days lapse before you file, the name goes back into the pool. If you’re waiting on a lease, financing, or a partner agreement and there’s real risk of missing the deadline, filing bare-bones formation documents and amending later is often safer than losing the name.

The State Search Doesn’t Cover Federal Trademarks

A clean result in the Illinois database says nothing about whether someone holds a federal trademark on the same name. State business registration and federal trademark registration are legally independent. A state trade name identifies your business in the state’s records; a federal trademark protects a brand nationwide.⁷

You can register a valid Illinois LLC name and still receive a cease-and-desist from a federal trademark holder. The names don’t even have to be identical. If they’re close enough in sound, appearance, or meaning that consumers might confuse the two businesses, you could face an infringement claim.⁸ The USPTO’s Trademark Search tool at tmsearch.uspto.gov is free. Run your name through it before you commit.

Domain Availability

Your legal business name and your website domain are separate registrations with no legal connection.⁹ Nothing stops you from operating as “Springfield Electronic Accessories LLC” while running your site at an unrelated address. Most owners still want the two to match, so it’s worth checking domain availability through any registrar before you file. If the .com is taken, decide whether you’d accept a different extension or a variation now, rather than after your paperwork is on record.

1
Illinois Secretary of State. Business Entity Search
2
Illinois General Assembly. Illinois Compiled Statutes 805 ILCS 5 Business Corporation Act of 1983 – Article 4 Name
3
Illinois General Assembly. Illinois Compiled Statutes 805 ILCS 180/1-10
4
Illinois Secretary of State. Application to Reserve a Corporate Name – Form BCA 4.10
5
Illinois Secretary of State. Application for Reservation of Name – Form LLC-1.15
6
Illinois General Assembly. Illinois Compiled Statutes 805 ILCS 5/4.10 – Reserved Name
7
United States Patent and Trademark Office. How Trademarks and Trade Names Differ
8
United States Patent and Trademark Office. Likelihood of Confusion
9
U.S. Small Business Administration. Choose Your Business Name