Illinois: Assumed-Name (DBA) Registration Requirements

Requirements one by one

Which track you're on

Illinois splits assumed-name registration by the kind of business you are:

• Individuals and general partnerships register under the Assumed Business
  Name Act (805 ILCS 405/1): you file with a county clerk and publish notice
  in a newspaper.
• Corporations, LLCs, limited partnerships, and limited liability
  partnerships are expressly outside that Act — it "shall in no way affect or
  apply to" them (§ 4). A registered entity that wants to operate under a name
  other than its true registered name instead adopts an assumed name with the
  Secretary of State under its own act (for a corporation, the Business
  Corporation Act, 805 ILCS 5/4.15).

An entity using its exact registered name files nothing at all.

The county-clerk track: file, then publish

If you are an individual or general partnership, you "file in the office of the
County Clerk of the County in which [you] conduct or transact ... business" a
certificate giving the assumed name and the owners' real names and addresses
(§ 1). Filing is required before you do business under the name.

Publication is not optional. You must publish notice of the filing "in a
newspaper of general circulation published within the county ... once a week for
3 consecutive weeks," with the first insertion "within 15 days after the
certificate is filed," and then file proof of publication with the clerk "within
50 days" (§ 1). The stakes are real: "Unless proof of publication is made to the
clerk, the certificate of registration of the assumed name is void."

Two wrinkles follow from this:

• Multi-county. If you later move or add a business location in another
  county, you file a fresh certificate there and republish (§ 1).
• A safety exception for home businesses. A person running the business from
  their residence who "reasonably believes that publishing his or her home
  address would put his or her safety at risk" may name the county clerk as the
  agent for service of process instead of publishing the home address, provided
  the request is backed by "a court order or police report" and the residence
  address is given to the clerk confidentially (§ 1a).

The Secretary of State track: registered entities

A corporation adopting an assumed corporate name files an application with the
Secretary of State before transacting business under it (805 ILCS 5/4.15(c)).
That right runs "until the first day of the anniversary month of the corporation
that falls within the next calendar year evenly divisible by 5," and is renewable
"for a period of 5 years" with the annual report (§ 4.15(d)–(e)). The assumed
corporate name must be distinguishable from existing names (§ 4.15(a)), so unlike
the county certificate it carries limited name priority. LLCs, LPs, and LLPs
register their assumed names with the Secretary of State under their own acts in
the same way.

Fees

On the county track, the clerk's statutory "indexing and filing" fee is $5.00
(§ 3), and you separately pay the newspaper for the three-week publication. On the
entity track, the Secretary of State's assumed-name filing and renewal fees are
set by the entity's governing act (§ 4.15(e)).

If you skip it

On the county track, conducting business without complying "shall be guilty of a
Class C misdemeanor, and each day ... shall be deemed a separate offense" (§ 5).
And because a certificate is "void" without proof of publication (§ 1), skipping
the newspaper step leaves you with no valid registration at all. The Act does not
add a general bar on suing.

What trips people up

• Publication is mandatory, and the registration is void without proof of it.
  Filing the certificate is only half the job; if you never publish and file the
  affidavit within 50 days, the certificate "is void" (§ 1).
• Corporations and LLCs do not use the county clerk. The Assumed Business Name
  Act "shall in no way affect or apply to" them (§ 4); a registered entity
  registers its assumed name with the Secretary of State (805 ILCS 5/4.15).
  Filing a county certificate for an LLC is the wrong route.
• A home-based owner can keep their address private. If publishing your home
  address would endanger you, § 1a lets you name the county clerk as service agent
  with a court order or police report instead of publishing the address.
• The county certificate does not lock up the name. It is an indexed public
  record and presumptive evidence of the facts (§ 3), not a property right in the
  name. Brand protection is a trademark question.

Common questions

I'm a sole proprietor in one county — what exactly do I do? File the assumed
business name certificate with your county clerk, then run a newspaper notice once
a week for three weeks (first within 15 days of filing) and file the proof within
50 days (§ 1). Budget the $5 clerk fee plus the paper's charge.

I formed an LLC — do I file with the county too? No. The Act excludes LLCs
(§ 4); you register any assumed name for the LLC with the Secretary of State.

What happens if I forget the newspaper step? Your certificate is void (§ 1),
so you are treated as unregistered — and operating unregistered on the county
track is a Class C misdemeanor, with each day a separate offense (§ 5).

I work from home and don't want my address in the paper — any options? Yes.
Section 1a lets a home-based owner who reasonably fears for their safety list the
county clerk as agent for service of process, backed by a court order or police
report, keeping the residence address confidential.

Statutes and sources

• 805 ILCS 405/1 — county-clerk filing, mandatory three-week publication, and
  the void-without-proof rule. Official text (accessed 2026-07-23).
• 805 ILCS 405/1a — home-based-business confidentiality option for the
  publication requirement. Official text (accessed 2026-07-23).
• 805 ILCS 405/3 — $5 county-clerk indexing/filing fee; certificate as
  presumptive evidence. Official text (accessed 2026-07-23).
• 805 ILCS 405/4 — the Act does not apply to corporations, LLCs, LPs, or LLPs.
  Official text (accessed 2026-07-23).
• 805 ILCS 405/5 — Class C misdemeanor for noncompliance, each day a separate
  offense. Official text (accessed 2026-07-23).
• 805 ILCS 5/4.15 — assumed corporate name: Secretary of State filing, term to
  the anniversary month in a year divisible by 5, and 5-year renewal. Official text (accessed 2026-07-23).