How to Register a DBA (Assumed Business Name) in Illinois

To register a DBA in Illinois, you file an assumed name certificate with either your County Clerk or the Illinois Secretary of State, depending on how your business is organized. Sole proprietors, general partnerships, and professional corporations file at the county level and then publish a newspaper notice. LLCs and corporations file directly with the Secretary of State. Fees start at a $5 statutory minimum for county filings and run to $120 for LLC registrations.

Where You File Depends on Your Business Type

Illinois law requires any business operating under a name other than the owner’s full legal name to register that name as an “assumed name.” Even minor additions trigger the requirement. Adding “Services” or “Company” to your personal name creates an assumed name that must be registered.

Your filing destination follows your entity type:

Sole proprietorships, general partnerships, and professional corporations file with the County Clerk in each county where the business operates. Operating in multiple counties means a separate certificate in each one.¹
LLCs file an assumed name application with the Illinois Secretary of State.²
Domestic and foreign corporations file with the Secretary of State under Section 4.15 of the Business Corporation Act.³

Filing at the County Clerk’s Office

Before you fill out the form, gather what the statute requires: the name you want to use, the full legal name of every owner, each owner’s mailing address, and every business address you’ll operate from in that county.¹

Search the name before you commit to it. The Illinois Secretary of State maintains a statewide business name database, but you also need to check your County Clerk’s records. A name that’s clear at the state level may already be taken in your county.

Pick up the assumed name application from your County Clerk’s office, either online or in person. Some counties require every owner’s signature to be notarized before they’ll accept the filing.⁴ Most offices accept filings in person, by mail, and in some cases online.

Fees vary by county. The statutory floor is $5, but counties routinely charge more.¹ Cook County charges $50,⁵ and Will County charges $10.⁶ Confirm the current fee and accepted payment methods with your county before you go.

Filing With the Secretary of State

LLCs and corporations skip the County Clerk entirely and file directly with the Secretary of State. The LLC filing fee is $120.² Corporations file under Section 4.15 of the Business Corporation Act, which requires a board resolution authorizing the assumed name and an application listing the corporation’s true name, its state of organization, and the proposed assumed name.³

State-level registrations expire. For corporations, the right to use an assumed name lasts until the first day of the corporation’s anniversary month in the next calendar year divisible by five. Renewal has to happen within the 60 days before that expiration date, or you lose the right to operate under the name until you refile.

Publishing the Newspaper Notice

County filers have one more step. After the certificate is filed, you must publish a notice in a newspaper of general circulation in the same county. The first publication has to run within 15 days of filing, and the notice must appear once a week for three consecutive weeks.¹

Publication costs vary. Community papers tend to charge less than larger metro publications, so call a few before you choose one.

After the final notice runs, the newspaper will provide a notarized certificate of publication and an original clipping. File that proof with the County Clerk within 50 days of your original filing date. Miss this deadline and the registration is void, meaning you start over.¹

After the Registration Is On File

If ownership, addresses, or partners change, file a supplemental certificate with the County Clerk to update the record.⁴ County registrations for sole proprietorships and general partnerships do not appear to carry a set expiration under the Assumed Business Name Act. Corporate filings with the Secretary of State, by contrast, must be renewed on the five-year cycle described above.

A DBA does not, by itself, change your taxes. A sole proprietor with a new assumed name still reports income on Schedule C using the same Social Security number or EIN. The IRS notes that certain business name changes may call for a new EIN, but that generally applies to structural changes like forming a new entity, not to simply adopting a trade name.⁷

Banks typically want to see the stamped certificate from the County Clerk or the Secretary of State’s confirmation before they’ll open an account in the DBA name. Bring it with you.

What Happens if You Don’t Register

Operating under an unregistered assumed name in Illinois is a Class C misdemeanor, and every day of unregistered operation counts as a separate offense. Penalties add up quickly. Beyond criminal exposure, an unregistered name can weaken your ability to enforce contracts under it, and banks will refuse to open accounts without the certificate.

What a DBA Does Not Give You

Registering an assumed name is not the same as trademarking it. Another business could use the same name in a different Illinois county, and your registration will not stop them. If you want exclusive rights to a business name, look at federal or state trademark registration as a separate process.

1
Illinois General Assembly. Illinois Compiled Statutes 805 ILCS 405 – Assumed Business Name Act
2
Illinois Secretary of State. Adopting an Assumed LLC Name
3
Illinois General Assembly. Illinois Compiled Statutes 805 ILCS 5/4.15 – Assumed Corporate Name
4
Adams County, IL. Assumed Name/DBA
5
Cook County Clerk. Assumed Business Name Registration
6
Will County Clerk. Register a Business Name
7
Internal Revenue Service. Business Name Change