The Assumed Business Name Act requires anyone operating a business in Illinois to register a "doing business as" name if it is different from owner's legal name. For example, if your name is Alexander Great, but you named your automotive repair business Candy's Repair Service, you must register it under this statute Depending on the structure of your business, you will be required to register at either the county or state level. Registering a DBA name in Illinois, also known as an alias or assumed name, requires submitting an application and paying a filing fee.

Register the Name 

If your business is a sole proprietorship, general partnership or professional services corporation, you must register the business' assumed name in the county where it operates. If Candy's Repair Service operates in Chicago, for instance, you must register the assumed name with the Cook County Clerk's office. On the other hand, if your business is a limited liability company or corporation, you must register the assumed name with the Secretary of State.

File the Application 

Obtain assumed name application from county clerk's office or Secretary of State. Many county clerks make applications available online. You can electronically file corporation assumed name and LLC assumed name application on the Illinois SOS website. Some counties, such as Cook County, also permit electronic filing. Provide the business' assumed name and address, owner's name and address, sign and date the application, and pay the filing fee. Applications filed at the county level must be signed in front of a notary public.

Publicize the Filing

For DBAs filed at the county level, you also must publish legal notice of the filing in a newspaper of general circulation within 15 days of filing. It must appear at least once per week for three consecutive weeks. After three-week run, the newspaper will provide you with a notarized Certificate of Publication and a clipping of original ad. Provide both documents within 50 days of file date. This serves as proof of publication. The clerk will record the assumed name and issue you an assumed name certificate.