What an Illinois LLC has to file, what it pays, and where to look it up. An LLC is a state entity, so every figure on this page is specific to Illinois.

Verified against the Illinois Limited Liability Company Act, the Illinois Department of Revenue and the Illinois Department of Employment Security, August 2026.

LLC rules, taxes, details Illinois

Formation

You form an Illinois LLC by filing Articles of Organization with the Illinois Secretary of State, Department of Business Services. Filing is done online at ilsos.gov.

It costs $150. An out-of-state LLC that wants to do business in Illinois files an Application for Admission, which also costs $150. A series LLC costs $400 either way.

The Articles of Organization must set out:

• The LLC name and the address of its principal place of business
• The purposes for which it is organised, which can be any lawful business
• The name of the registered agent and the address of the registered office
• Confirmation that there is at least one member at the time of filing
• The name and business address of every manager, and of any member with the authority of a manager
• The duration, which is perpetual unless you say otherwise
• The name and address of each organiser

Naming rules

• The name must contain Limited Liability Company, L.L.C. or LLC.
• The name has to be distinguishable from every other entity already on the Secretary of State register.
• Some words need consent from another agency before they can be used, including words suggesting banking or insurance.

Registered agent

Every Illinois LLC must keep a registered agent and a registered office on file.

• The agent is either an individual resident of Illinois, or an entity authorised to do business in Illinois.
• The registered office must be an Illinois street address, not a PO Box.
• Changing the registered agent or the registered office address costs $25.

Annual report

• The annual report costs $75.
• It is due within the 60 days immediately before the first day of the anniversary month of formation. If the LLC was formed in June, the window is roughly 1 April to 31 May.
• Miss it and the penalty is $100, charged once the report is still unfiled on the first day of the second month after the anniversary month. A further $100 is added for each year, or part of a year, from the second year of delinquency.
• A delinquent LLC is noted as such on the public record and is blocked from making other filings until it is put right.
• Reinstatement costs $200 on top of the outstanding reports and penalties.

Full fee schedule

Articles of Organization:	$150.00
Articles of Organization for a series LLC:	$400.00
Application for Admission, foreign LLC:	$150.00
Application for Admission, foreign series LLC:	$400.00
Articles of Amendment, domestic or foreign:	$50.00
Statement of change of registered agent or registered office:	$25.00
Annual report:	$75.00
Annual report for each series with an active certificate of designation:	$50.00
Penalty for a delinquent annual report:	$100.00
for each year or part year from the second year	$100.00
Application for reinstatement:	$200.00
Copy, certified copy or certificate:	$25.00

Two details people get wrong

The annual report deadline is a window, not a date. Illinois wants it in the 60 days before your anniversary month starts, which means the deadline moves with the month you formed in rather than sitting on a fixed calendar date like most states. People who diarise “the end of the year” miss it.

Illinois taxes the LLC itself, even though it is a pass-through. The Personal Property Replacement Tax is charged at 1.5% of net income on LLCs treated as partnerships. It is easy to miss because most people expect a pass-through entity to owe nothing at state level, and it is a genuine entity-level tax on top of what the members pay personally.

LLC tax information Illinois

Illinois has a flat personal income tax, and a replacement tax that catches pass-through entities other states leave alone.

Federal classification

• A single-member LLC is disregarded by default. The income reports on the member’s personal return.
• A multi-member LLC is a partnership by default. It files Form 1065, with a K-1 to each member, due 15 March.
• An LLC can elect corporate treatment instead. Form 8832 gives C corp treatment, Form 2553 gives S corp treatment. An S corp files 1120-S by 15 March, a C corp files 1120 by 15 April.

Illinois state taxes

• Personal income tax: yes, at a flat 4.95% of net income. Illinois does not use graduated brackets.
• Personal Property Replacement Tax: 1.5% of net income for an LLC treated as a partnership, and for S corporations and trusts. Corporations pay 2.5% replacement tax on top of 7% corporate income tax.
• LLC return: Form IL-1065, the Partnership Replacement Tax Return, including Schedule B. It is due on or before the 15th day of the 4th month after the close of the tax year, with an automatic six-month extension available.
• Pass-through entity tax election: optional, at 4.95% of net income, with a matching credit to the members on their share.
• Sales tax: Illinois charges Retailers’ Occupation Tax at state level, with a lower rate for qualifying food, drugs and medical appliances. Home rule, mass transit, park district, county public safety and school facility taxes then stack on top, so the real rate at any given address is materially higher than the state rate, and Chicago’s combined rate is among the highest of any major American city. Use the MyTax Illinois Tax Rate Finder for the address you actually sell from.
• Unemployment insurance: for 2026 a new employer pays 3.350%, or 3.450% in administrative support and waste management, on the first $14,250 of each employee’s wages. Experience rates run from 0.750% to 7.050%.

LLC lookup Illinois

Illinois records are public and free to search. The record shows status, formation date, registered agent and whether the annual report is current.

Search the register

The business entity search sits at ilsos.gov.

• By entity name. The one most people need. It confirms whether a name is taken and whether the entity is in Good Standing or shown as delinquent.
• By file number. Goes straight to one record when you already hold the number.
• By registered agent. Useful for diligence on a counterparty.

A status other than Good Standing usually means an annual report is outstanding, which is a quick and reliable tell about how a company is being run.

File and register

• Secretary of State, at ilsos.gov. Form the LLC, file the annual report, amend, change the registered agent, or reinstate.
• Department of Revenue, at mytax.illinois.gov. Register for the replacement tax, sales tax and withholding. This is separate from the Secretary of State.

Getting help with an Illinois LLC

indinero handles the accounting, tax and CFO work behind all of this for Illinois LLCs. If you would rather not track the anniversary month window and the replacement tax yourself, talk to an expert.

Fees and rates are taken from the Illinois Limited Liability Company Act, the Illinois Department of Revenue and the Illinois Department of Employment Security, and were verified in August 2026. They change. This page is general information, not tax or legal advice for your situation.

LLC information by state: California, Texas, Florida, New York, Pennsylvania, Illinois, Ohio, Georgia, North Carolina, Michigan.