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Before going into the details, here is a quick checklist for registering a DBA in Illinois.
| Official Term | Assumed name (also called an assumed business name or DBA) [1] |
|---|---|
| Filing Agency | Illinois Secretary of State for LLCs and corporations [1]; the county clerk for sole proprietors and general partnerships [2] |
| Form | LLC Form LLC-1.20 at the Secretary of State; a county assumed business name application at the county clerk [4] |
| State Fee | Secretary of State assumed LLC name fee is prorated on a 5-year cycle ($30 to $150); [1] Cook County charges $50 [2] |
| Processing Time | Varies by office; county filings add a newspaper publication period |
| Renewal Required | Secretary of State assumed names renew every 5 years; county rules vary [1] |
| Cancellation | Withdraw or cancel through the office where you filed [2] |
A DBA stands for "Doing Business As." It is an alternative name your business uses instead of its registered legal name. In Illinois, the official term is "assumed name," and where you file depends on your business structure.
LLCs and corporations register an assumed name with the Illinois Secretary of State. sole proprietors and general partnerships register an assumed business name with the county clerk under the Assumed Business Name Act. [5]
A DBA does not create a new legal entity. It does not change your tax status, your liability protection, or your ownership. It is only a name your business is authorized to operate under.
| Brand Fit | Commercial Banking | Multi-Entity Branding | Privacy & Trust |
|---|---|---|---|
| Sole proprietors operate under their personal names by default. An assumed name lets you do business under a professional brand instead. | Illinois banks generally require a registered assumed name before opening a business account in a name other than your legal name. | One business can run several brands or product lines under separate assumed names without forming a new company for each. | An assumed name keeps your personal identity off public branding and signals to customers that you are an established business. |
How you register an assumed name in Illinois depends on your business type. LLCs and corporations file with the Illinois Secretary of State. Sole proprietors and general partnerships file with the county clerk and must publish a notice in a local newspaper. [2]
Before you file, confirm the name you want is available. LLCs and corporations search the Secretary of State business database; sole proprietors search the county clerk index. [1]
Because no single office checks every name across the state and for trademark conflicts, a careful search protects your brand before you commit to it.
Illinois assumed name rules are light, but a few hard limits apply.
| Your assumed name should be distinguishable | Match designators to your real structure | Conflicts are your responsibility |
|---|---|---|
| The Secretary of State will reject an assumed LLC name that is not distinguishable from an existing name on file. [1] | A sole proprietor should not use "LLC," "Inc.," or "Corp" in an assumed name. An organizational identifier must match your actual business structure. | Neither the state nor the county screens for trademark conflicts, so run a federal trademark search to avoid infringing a protected mark. [3] |
Run a trademark search at the U.S. Patent and Trademark Office (USPTO) as well. Registering an assumed name in Illinois gives you no trademark rights and does not stop a federal trademark holder from challenging your use of the name. [3]
LLCs and corporations file an application to adopt an assumed name with the Illinois Secretary of State (LLCs use Form LLC-1.20). Sole proprietors and general partnerships file an assumed business name application with the county clerk. [4]
| Situation | Fee |
|---|---|
| LLC assumed name at the Secretary of State | Prorated on a 5-year cycle, $30 to $150 [1] |
| Assumed business name at the county clerk | Varies by county; $50 in Cook County [2] |
| Newspaper publication (county filings) | Publish once a week for 3 consecutive weeks, then file proof [2] |
Secretary of State (LLCs and corporations): File the assumed name application with the Illinois Secretary of State Business Services [1]
County clerk (sole proprietors and partnerships): File with your county clerk and complete the required newspaper publication [2]
Note: Filing fees and publication fees are generally non-refundable. If your application is rejected or incomplete, you must correct and re-file it.
After you file, the Secretary of State or the county clerk records your assumed name. County filings are not complete until the newspaper publication runs and you file proof of publication.
Keep your file-stamped registration and any Certificate of Publication. Banks, vendors, and payment processors will ask for proof before they let you operate or accept funds under the assumed name.
A Secretary of State assumed name must be renewed every 5 years. County assumed business name rules vary, so confirm the renewal and cancellation steps with your county clerk. [1]
A DBA and an LLC are not the same thing. This is one of the most common points of confusion for new business owners, and getting it wrong can be costly.
A DBA is only a name. It does not create a legal entity. It does not protect your personal assets. If someone sues your business, your personal finances are exposed.
Forming an LLC means you are creating a separate legal entity. That separation generally protects your personal finances, home, and savings from business debts and lawsuits.
If you are a sole proprietor who wants a business name without incorporating, an assumed name is a fast, affordable option. If you want liability protection, you need an LLC or a corporation.
Many businesses do both: they form an LLC and then apply for a DBA to run a brand under a name different from the LLC legal name.
| Feature | DBA (Assumed Name) | LLC |
|---|---|---|
| Creates a legal entity | No | Yes |
| Personal asset protection | No | Yes |
| Changes the tax treatment | No | Can elect a different tax status |
| Required to operate under a different name | Yes, if the name differs from your legal name | No, the LLC name is its legal name |
| Cost to register | State or county fee + Swyft service fee | State filing fee + Swyft service fee |
Most Illinois assumed name problems come down to the same handful of errors. Here is what to watch out for before you file.
LLCs and corporations file with the Secretary of State, while sole proprietors and general partnerships file with the county clerk. Filing in the wrong place wastes time and money. [1]
The county assumed business name filings require publication once a week for 3 consecutive weeks, plus a Certificate of Publication. Skipping it leaves your registration incomplete. [2]
A sole proprietor cannot include "LLC," "Inc.," or "Corp" in an assumed name unless the business is actually organized that way. The designator must match your real structure.
A Secretary of State assumed name must be renewed every 5 years. Calendar the renewal so your right to the name does not lapse. [1]
An assumed name is only a name. It does not create a legal entity and does not shield your personal finances. If you want protection, form an LLC.
State or county approval is not trademark clearance. A federal trademark holder could still force you to stop using the name. [3]
[1] Illinois Secretary of State. Business Filings. Accessed on June 4, 2026.
[2] Cook County Clerk. Assumed Business Name Registration. Accessed on June 4, 2026.
[3] U.S. Patent and Trademark Office (USPTO). Trademarks. Accessed on June 4, 2026.
[4] Illinois General Assembly. 805 ILCS 180/1-20, Adoption of Assumed Name. Accessed on June 4, 2026.
[5] Justia. 805 ILCS 405, Assumed Business Name Act. Accessed on June 4, 2026.