Illinois Business Name Checker
Check if your business name is available in Illinois. Validate IL naming rules instantly, then search the Illinois Secretary of State's Business Entity Search free on ilsos.gov — including assumed and reserved names that block yours.
Validate the name format, then search the official Illinois Secretary of State — Corporation/LLC Search records.
1.Search the state registry (Illinois Secretary of State — Corporation/LLC Search) for existing LLCs, corporations, and reserved names
2.Check federal trademarks at USPTO.gov — state approval does not protect you from trademark claims
3.Verify the .com domain is available for your name
4.Grab matching social media handles (Instagram, X, LinkedIn, Facebook)
5.Lock the name in by filing your formation documents — or reserve it first (details below)
Fee
$25
Holds the name for
90 days
How to file
Form LLC-1.15 by mail (corporations use Form BCA 4.10, also $25 for 90 days)
Renewable by filing a new Form LLC-1.15 with another $25 — the fee is not credited toward your formation filing. Cancelling a reservation costs $5 and transferring it costs $25.
How Business Name Availability Works in Illinois
Illinois names are checked through the Secretary of State's Business Entity Search on ilsos.gov, run by the Department of Business Services. The search is free and shows each entity's status, file number, and agent details. Illinois casts a wide net on conflicts: your name must be distinguishable not just from active LLCs and corporations, but also from assumed names and reserved or registered names already on file.
The designator rules come from 805 ILCS 180/1-10: an LLC name must contain "Limited Liability Company," "L.L.C.," or "LLC," and a low-profit L3C must use the "L3C" designator. Corporations follow 805 ILCS 5/4.05 with the usual "corporation," "company," "incorporated," or "limited" options. Words like "bank" or "trust" need sign-off from the IDFPR — the Illinois Department of Financial and Professional Regulation.
Illinois has two fee quirks worth knowing before you file. A series LLC costs $400 to form versus $150 for a standard LLC. And the assumed-name (DBA) fee is prorated by calendar year in a way no other state uses: $150 in years ending in 0 or 5, sliding down to $30 in years ending in 4 or 9, because all assumed names renew on the same 5-year cycle.
Illinois Business Name Requirements
✓ Name Requirements
- • LLCs must include "LLC", "L.L.C." or "Limited Liability Company"
- • Corporations must include "Inc.", "Corp.", "Co." or "Ltd."
- • Must be distinguishable from every domestic or foreign LLC or corporation name, assumed name, and reserved or registered name on file with the Illinois Secretary of State
- • Cannot suggest a government affiliation
- • Cannot be misleading about business purpose
- • Governed by 805 ILCS 180/1-10 (LLCs) and 805 ILCS 5/4.05 (corporations)
✗ Restricted Words
- • "Bank" — requires sign-off from the Illinois Department of Financial and Professional Regulation (IDFPR)
- • "Trust" — implies fiduciary powers — IDFPR approval needed
- • "Insurance" — requires clearance from the Illinois Department of Insurance
- • "Engineer" — implies licensed professional practice — IDFPR licensure required
- • "University" — words implying an educational institution can require approval from Illinois education authorities
- • "College" — words implying an educational institution can require approval from Illinois education authorities
- • "Olympic" — federally protected under the Ted Stevens Olympic and Amateur Sports Act
How to Check Name Availability in Illinois
Use the tool above to open the Illinois Secretary of State — Corporation/LLC Search search and look up existing LLCs, corporations, and reserved names. Illinois prorates the LLC assumed-name fee by calendar year — anywhere from $150 down to $30 depending on where you are in the 5-year cycle — and charges $400 to form a series LLC versus $150 standard.
Search the USPTO database at uspto.gov — clearing the Illinois registry does not protect you from a federal trademark claim.
Check that the matching .com domain is available before you commit — renaming an LLC later means an amendment filing and new bank paperwork.
Confirm your name is free on Instagram, X, Facebook, and LinkedIn so your branding stays consistent everywhere.
Illinois lets you reserve a name for 90 days for $25 — Form LLC-1.15 by mail (corporations use Form BCA 4.10, also $25 for 90 days).
What Registering a Name Costs in Illinois
| Filing | State Fee | Frequency |
|---|---|---|
| LLC formation filing | $150 | One-time |
| Annual report / recurring fee | $75 | Yearly |
| Name reservation | $25 | Holds the name 90 days |
| Assumed Name (Form LLC-1.20) | LLCs file an Application to Adopt an Assumed Name with the Secretary of State; the fee is prorated by where the calendar year falls in a 5-year cycle — $150, $120, $90, $60, or $30 — with a $150 renewal every five years. Sole proprietors register at the county clerk under the Assumed Business Name Act. | |
State filing fees as of 2026. See the Illinois LLC tax and fee calculator for the full annual cost picture.
Frequently Asked Questions
How do I check if a business name is taken in Illinois for free?
Use the Illinois Secretary of State's Business Entity Search on ilsos.gov — it is free and shows entity status, file numbers, and agent information. Remember that Illinois checks your proposed name against more than active companies: assumed names and reserved or registered names also block a filing, so search partial matches of your key words, not just the exact name you plan to use.
How much does it cost to reserve a business name in Illinois?
An Illinois name reservation costs $25 and holds the name for 90 days. LLCs file Form LLC-1.15 by mail; corporations use Form BCA 4.10 on the same terms. You can renew by filing a new application with another $25, cancel for $5, or transfer the reservation for $25. Note that the reservation fee is not credited toward your $150 Articles of Organization when you eventually form the LLC.
What suffix does an Illinois LLC name need?
Under 805 ILCS 180/1-10, an Illinois LLC name must contain "Limited Liability Company," "L.L.C.," or "LLC." If you form a low-profit limited liability company, the name must use the "L3C" designator instead. Corporations follow 805 ILCS 5/4.05 and need "corporation," "company," "incorporated," or "limited" or an abbreviation such as Inc., Corp., Co., or Ltd.
Why does the Illinois assumed name (DBA) fee change every year?
Because all Illinois LLC assumed names renew on the same statewide 5-year cycle, the initial fee for Form LLC-1.20 is prorated by calendar year: $150 in years ending in 0 or 5, then $120, $90, $60, and $30 in years ending in 4 or 9. After that, renewal costs a flat $150 for each five-year period. Filing late in the cycle is cheaper up front but brings the renewal date closer.
How much does a series LLC cost in Illinois?
Illinois charges $400 to form a series LLC, compared with $150 for a standard LLC. The series structure lets one master LLC establish internal series with separate assets, members, and liabilities. Each designated series also involves its own certificate filing, so budget beyond the formation fee. For most single-business founders, the standard $150 LLC is the simpler and cheaper choice; the series form mainly suits real-estate portfolios and similar multi-asset setups.
What are the ongoing costs for an Illinois LLC?
After the $150 formation fee (or $400 for a series LLC), Illinois charges a $75 annual report to keep the LLC in good standing. If you operate under an assumed name, add the prorated Form LLC-1.20 fee and its $150 five-year renewals. Miss the annual report and the Secretary of State assesses penalties and can eventually dissolve the LLC administratively, which puts your name back in play for others.
Related Tools
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Business Entity Search Directory
Official Secretary of State search portals for all 50 states — look up any registered company.
Checking a Name in Another State?
Searching Illinois Business Names on ilsos.gov
Start with the Secretary of State's free Business Entity Search. Search the distinctive words of your proposed name and review both exact and partial matches — Illinois checks your name against domestic and foreign LLCs and corporations, plus assumed names and reserved or registered names, so a conflict can hide in places a casual search misses.
If your name is clear and you are not ready to form, reserve it: Form LLC-1.15, filed by mail with a $25 fee, holds the name for 90 days. Corporations use Form BCA 4.10 on the same terms. The reservation is renewable by repeating the process, a cancellation costs $5, and a transfer to another person costs $25 — but note the $25 is not credited against your formation fee.
Formation itself is $150 for a standard LLC's Articles of Organization, and Illinois follows up with a $75 annual report. If you want a series LLC — separate internal cells with their own assets and members — the formation fee jumps to $400.
Illinois Naming Rules, L3Cs, and Restricted Words
Under 805 ILCS 180/1-10, an Illinois LLC name must contain "Limited Liability Company," "L.L.C.," or "LLC." Illinois also recognizes the low-profit limited liability company, and an L3C must carry the "L3C" designator in its name. Corporations need "corporation," "company," "incorporated," or "limited" (or an abbreviation) under 805 ILCS 5/4.05.
Illinois's distinguishability test is broad: the name must differ from every domestic or foreign LLC or corporation name, every assumed name, and every reserved or registered name on the Secretary of State's records. A brand someone registered as a DBA can block your LLC filing even though no entity carries that exact legal name.
Financial words get extra scrutiny. "Bank" and "trust" require sign-off from the Illinois Department of Financial and Professional Regulation (IDFPR), and "insurance" runs through the Department of Insurance. Professional titles like "engineer" also imply IDFPR licensure — plan an approval step into your timeline if your name touches any regulated field.
The Prorated Assumed-Name Fee: Illinois's Oddest Rule
If your Illinois LLC will operate under a different brand, you file an Application to Adopt an Assumed Name (Form LLC-1.20) with the Secretary of State. Here is the odd part: all Illinois assumed names expire on the same statewide 5-year cycle, so your fee is prorated by the calendar year you file — $150 in years ending in 0 or 5, then $120, $90, $60, and just $30 in years ending in 4 or 9. Renewal is a flat $150 for each new five-year period.
The practical takeaway: filing an assumed name late in the cycle is dramatically cheaper, but you will hit the $150 renewal sooner. Either way the registration must be kept current, and the assumed name is checked for conflicts — unlike many states, Illinois will not register an assumed name that collides with an existing entity or assumed name.
Sole proprietors and general partnerships do not use Form LLC-1.20. They register under the Assumed Business Name Act at the county clerk in each county where they do business, with fees and publication requirements that vary by county.
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