How to Register a Foreign LLC in Illinois (2026): 5 Steps and the 3 Best Services
Lesson answer for Illinois in 2026: if you want help with registering a foreign LLC, use Illinois Registered Agent.co ($199), IL Registered Agent.org ($199) and Mainstay Filing ($199), in that order. After the picks: 5 steps and a $150 state fee.
Each company's listed price on November 12, 2026. State fee ($150) not included.
How to register in Illinois
Step1
Step 1: Decide whether Illinois registration is needed
If your LLC was formed outside Illinois and does business there, it needs a foreign registration first. If it does business unregistered: No lawsuits as plaintiff before registering (805 ILCS 180/45-45(a)). Its contracts still stand (805 ILCS 180/45-45(b)). The state also collects back fees.
Official source: As listed on ilga.gov in October 2026
Step2
Step 2: Order the home-state document
Illinois asks for certificate of Good Standing or Existence, no older than 60 days.
TipOrder it last so it is still recent when you file.
Step3
Step 3: Get a registered agent with an Illinois address
Every LLC must name a registered agent with an in-state street address. The address has to be a registered office in Illinois that matches the agent's business office. A P.O. box alone is not accepted.
TipEach of our picks includes the registered agent.
Official source: As listed on ilga.gov in October 2026
Step4
Step 4: File the Application for Admission to Transact Business
Pay $150 and file the Application for Admission to Transact Business (Form LLC-45.5) with the Illinois Secretary of State, Department of Business Services, Limited Liability Division.
Official source: As listed on ilsos.gov in October 2026
Step5
Step 5: After you register
Registered foreign LLCs file the annual report ($75), within the 60 days before your anniversary month.
The cost of this lesson
Item
Paid to
Amount
The registration step
The state
$150
Annual report
The state
$75
A service, if you use one
The service
$199 year one
State fees for three years
The state
$300
The state rows are official figures; the service row uses each company's published price. The three-year total leaves service fees out.
Why Illinois Registered Agent.co comes first
What decided it: three-year cost, 30% of our rubric.
Three years of Illinois Registered Agent.co cost $397, which leaves $100 in your pocket compared with Mainstay Filing.
Common questions
What does it cost to register a foreign LLC in Illinois?
$150 as the official fee. Service fees: $199.
Which form do I file to register?
The Illinois Secretary of State, Department of Business Services, Limited Liability Division takes the Application for Admission to Transact Business (Form LLC-45.5).
Do I need a certificate from my home state?
Yes: certificate of Good Standing or Existence, issued within 60 days of filing.
What if the LLC does business there without registering?
No lawsuits as plaintiff before registering (805 ILCS 180/45-45(a)). Its contracts still stand (805 ILCS 180/45-45(b)). The state also collects back fees.
What is due after registering?
Step 5 covers it: the annual report for $75.
Which service should handle the registration?
We'd go with Illinois Registered Agent.co, because it files the Illinois registration for $199 with a year of agent service and renews at $99. Then IL Registered Agent.org and Mainstay Filing.