3 Best Foreign Registration Services in Illinois (2026)
LLC Review Desk's 2026 picks for foreign registration services in Illinois, favorite first, are Illinois Registered Agent.co ($199), IL Registered Agent.org ($199) and Mainstay Filing ($199). Illinois Registered Agent.co is our favorite, because it's $199 plus the state fee, with your first registered agent year included, then $99 a year for the agent.
By the LLC Review Desk editorial team
Position 1
Best here
1. Illinois Registered Agent.co: best for companies adding only Illinois
Service fee $199, state fee extra; $99 a year for the agent from year two
Our score
9.1out of 10
9.1 out of 10
Our favorite is Illinois Registered Agent.co, because registering in Illinois costs $199 and covers year one as your agent, then $99 a year.
You get a street address in the state for your registered office, and any papers served on the company are scanned into your online account.
Its three-year total is lower than Mainstay Filing's, and that matters a lot in our scoring.
In the price
The registration filing
A first year as your registered agent
What we like
Covers your first year of registered agent service
Keeping the agent costs $99 yearly
$199 covers the registration work; fees are extra
Trade-offs
Illinois only; your home state needs its own agent
LLC Review Desk gives each score out of 10 itself, based on the criteria on How we rank. No customer ratings are involved.
What Illinois foreign registration services cost in 2026: year one, renewals and three years
Service
First year
Second year
Third year
Three-year total
Agent covered in year one
Illinois Registered Agent.co
$199
$99
$99
$397
Included
IL Registered Agent.org
$199
$99
$99
$397
Included
Mainstay Filing
$199
$149
$149
$497
Free
We took each price from the company's own pages on November 12, 2026. On top of every row, Illinois charges a $150 registration fee, which isn't in these totals.
How we scored these
Here's how we scored it: three-year cost and filings in the price are worth 29% each, and renewal price, state fit and up-front totals split the other 42%. In Illinois, three-year cost made the difference.
Illinois Registered Agent.co comes to $397 over three years, which is $100 less than Mainstay Filing. Both include the first year, so the renewal price decided it.
You can read every criterion and weight on How we rank.
Registering a foreign LLC in Illinois: fee, form and who to send it to
You register through the Illinois Secretary of State, Department of Business Services, Limited Liability Division, using the Application for Admission to Transact Business (Form LLC-45.5). The state charges $150. Illinois also wants certificate of Good Standing or Existence that is no more than 60 days old.
After that, plan on the annual report each cycle ($75) by within the 60 days before your anniversary month.
Get these ready first
Certificate of Good Standing or Existence, issued within 60 days of when you file.
Your company's full legal name, exactly as registered at home, and the date it was formed there.
A registered agent with a street address in the state. Any service on this page can do it.
The $150 state fee to pay with the filing.
A reminder for yourself about the annual report and its $75 fee.
What happens if you skip Illinois registration
Until it registers, an out-of-state LLC can't sue in Illinois courts (805 ILCS 180/45-45(a)). Its contracts still stand (805 ILCS 180/45-45(b)). You may also owe fees for the time you were unregistered.
Your questions about Illinois foreign registration services
Do I have to register my out-of-state LLC in Illinois?
If it does business there, yes. Until it registers, it can't sue in the state's courts.
What does registering a foreign LLC in Illinois come to?
The state charges $150, and services charge $199.
What form does Illinois use for foreign LLCs?
The state's form is the Application for Admission to Transact Business (Form LLC-45.5), and it goes to the Illinois Secretary of State, Department of Business Services, Limited Liability Division.
Does Illinois want paperwork from my home state?
It does: certificate of Good Standing or Existence, no more than 60 days old.
Do I still need a registered agent after I register?
Yes. You keep a registered agent with a street address in the state as long as the company stays registered.
Who's the best choice for foreign registration in Illinois?
Illinois Registered Agent.co, because $199 beyond the state fee gets you registered in Illinois, and the agent renews at $99.