Can a sole proprietorship become an LLC in Illinois?

Yes. A sole proprietorship is not a legal entity separate from its owner, so you convert by forming a new Illinois LLC and moving the business into it. File Articles of Organization (Form LLC-5.5) with the Illinois Secretary of State and pay the $150 filing fee. On the EIN, the IRS says a single-member LLC can keep using your sole proprietor EIN if it does not choose corporate or S-Corporation tax treatment, has no employees and owes no excise tax; otherwise it needs its own EIN, which you apply for on Form SS-4. Update your business licenses with the city or county where you operate, and check whether any state tax registrations must be reissued in the LLC's name. Forming the LLC gives you limited liability protection that a sole proprietorship lacks. Confirm current fees and submission requirements with the Secretary of State before filing.

Does forming an LLC in Illinois reduce self-employment tax?

No, forming an Illinois LLC doesn't by itself reduce self-employment tax. By default, a single-member LLC is taxed like a sole proprietorship and a multi-member LLC like a partnership, and the owners generally owe 15.3% self-employment tax on net self-employment earnings. Self-employment tax is a federal tax paid to the IRS, not to a state agency: it is 12.4% for Social Security, which applies only up to an annual earnings cap, plus 2.9% for Medicare. However, an eligible LLC can file Form 2553 (Election by a Small Business Corporation) with the IRS to be taxed as an S-Corporation. You then pay yourself a reasonable salary, which is subject to Social Security and Medicare payroll taxes, and take remaining profits as distributions, which are not. The trade-off: an S-Corporation must run payroll, file payroll tax returns and a separate federal return (Form 1120-S), and pay for the accounting that requires. In Illinois, an LLC taxed as an S-Corporation also pays the 1.5% Personal Property Replacement Tax on its net Illinois income, so include it in the model. Whether the tax savings exceed those costs depends on your profits. Next step: consult an Illinois CPA to model the savings based on your projected income before filing Form 2553.

Does an Illinois LLC protect personal assets?

Yes. Under Illinois law, the debts, obligations and liabilities of an Illinois LLC, whether arising in contract, tort or otherwise, are solely the company's, and a member or manager is not personally liable for them solely by reason of being or acting as a member or manager. That protection has limits. It does not cover, for example, a debt you personally guarantee, and the same law says it does not limit liability imposed by other law, including the law of agency, contracts and torts, or court-imposed remedies such as piercing the LLC veil, so you remain liable for your own wrongful acts. Illinois law also says that an LLC's failure to observe the usual company formalities is not a ground for imposing personal liability on its members or managers, so skipping meetings or minutes is not, by itself, a ground for losing your protection. Keeping a separate business bank account and never mixing personal and business funds are still sensible practices, because courts can in some cases disregard an LLC and reach its owners ("piercing the veil"), and commingled funds invite that argument. If a creditor wins a judgment against your LLC for a company obligation you did not guarantee, it generally collects from the LLC's assets, not your personal home and savings. To secure this protection, file your Articles of Organization with the Illinois Secretary of State and open a dedicated business bank account from day one.

Can one person own an LLC in Illinois?

Yes, Illinois allows single-member LLCs owned and controlled by one person, who can also manage the company. For federal tax purposes, the IRS treats a single-member LLC as a disregarded entity by default, so the LLC's income is reported on your personal return, just as with a sole proprietorship. An eligible LLC can instead elect S-Corporation tax treatment by filing Form 2553 with the IRS, which can reduce self-employment taxes on profits taken as distributions. The practical benefit: you gain personal liability protection for business debts while keeping tax filing simple. Illinois charges $150 to file Articles of Organization with the Illinois Secretary of State, and a $75 annual report each year. Next step: file your Articles of Organization with the Secretary of State, then open a business bank account to keep business and personal finances separate. The IRS says a single-member LLC with no employees, no excise tax and no corporate tax election can use your sole proprietor EIN instead of getting a new one.

Is a sole proprietorship legal in Illinois without registration?

Yes, sole proprietorships don't require a formation filing in Illinois. You become a sole proprietor the moment you start conducting business, with no filing at the Secretary of State. There are still caveats. If you operate under a name other than your own legal name, check whether Illinois or your city or county requires you to register it as an assumed or trade name before you use it. Check with your city or county whether your type of business needs a local license, since local requirements and fees vary. Certain professions, such as real estate agents and health practitioners, require specific state licenses from their licensing boards. The practical implication: while you avoid the LLC filing fee and any LLC reports, you remain personally liable for all business debts and legal judgments, unlike an LLC owner. Your next step: contact your city or county to confirm licensing requirements and fees for your specific business type and location.

Illinois LLC vs Sole Proprietorship: Complete 2026 Comparison

Compare an LLC and a sole proprietorship in Illinois: liability, taxes, costs and paperwork.

By Edmond Hui · Last updated: October 2026

In Illinois, an LLC fits when you have personal assets to protect from business liabilities and lawsuits; a sole proprietorship fits when you're testing a low-risk business idea with minimal startup costs. Compare both structures in detail below.

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Comparison chart for Illinois LLC versus Sole Proprietorship, contrasting liability, taxation and ongoing filing burden across 8 factors. — Side-by-side on the factors that decide the choice, for Illinois. Source: Illinois Secretary of State.

LLC vs Sole Proprietorship: Side-by-Side

Factor	LLC	Sole Proprietorship
Personal liability protection	Limited liability: members are not personally liable for the LLC's debts and obligations solely because they are members	No protection: you're personally liable for all business debts and legal claims
Formation cost & paperwork	$150 filing fee for Articles of Organization (Form LLC-5.5) with the Illinois Secretary of State ($400 for a series LLC)	No formation filing required, just start doing business
Taxation	Pass-through for federal income tax by default, with a corporate or S-Corp election available; partnership or S-Corp status adds Illinois' 1.5% replacement tax	Pass-through only: all business income is reported on your personal return (Schedule C)
Self-employment tax	15.3% self-employment tax on net self-employment earnings by default (Social Security part capped yearly); an S-Corp election may reduce it at higher profits	15.3% self-employment tax on net self-employment earnings (Social Security part capped yearly); a sole proprietorship cannot elect S-Corp status
Business credibility	Professional appearance with 'LLC' designation can help with customers, vendors, and lenders	May appear less established: operates under your personal name or a trade name
Banking & contracts	Separate business bank account recommended to keep LLC and personal funds apart; easier to get business credit cards and loans	Can use personal accounts, though a separate account makes business records and taxes easier to track
State fees in Illinois	$150 one-time filing fee, plus a $75 annual report each year	$0 to form: no formation filing (an assumed or trade name filing may apply if you use a business name)
Conversion path to LLC	Already an LLC: can elect different tax treatments as the business grows	You can form an Illinois LLC later by filing Articles of Organization

When an LLC Makes More Sense

You have personal assets to protect from business liabilities and lawsuits
You want professional credibility and easier access to business banking and credit
Your profits are high enough that an S-Corp election's self-employment tax savings would outweigh the added payroll and accounting costs
You plan to have business partners or investors in the future

When a Sole Proprietorship Makes More Sense

You're testing a low-risk business idea with minimal startup costs
Your business has low liability risk (like freelance writing)
You want to avoid the $150 Illinois filing fee, the $75 annual report and LLC filing paperwork
Your income is modest and you want maximum tax simplicity

Tax Deep Dive

Sole Proprietorship Tax

Sole proprietorships report business income on Schedule C of your personal federal return. You pay regular income tax plus 15.3% self-employment tax on net self-employment earnings, with the 12.4% Social Security part applying only up to an annual earnings cap, and a sole proprietorship cannot elect S-Corporation tax treatment.

LLC Default Tax

By default, a single-member LLC is a 'disregarded entity' for federal tax purposes, taxed like a sole proprietorship, and a multi-member LLC is taxed as a partnership. Either way, you generally still owe self-employment tax on net self-employment earnings, but an LLC can elect a different tax treatment as your business grows. In Illinois, an LLC taxed as a partnership also pays the state's Personal Property Replacement Tax of 1.5% of its net Illinois income.

LLC S-Corp Election

Illinois LLCs can elect S-Corporation tax status to split income into a reasonable salary (subject to Social Security and Medicare payroll taxes) and distributions (not subject to those taxes). Whether it saves money depends on your profits and the added payroll and accounting costs, so have a CPA model it before electing. In Illinois, an LLC taxed as an S-Corporation also pays the 1.5% Personal Property Replacement Tax on its net Illinois income, so include it in the model.

This guide is general information, not legal or tax advice, and reading it does not create an attorney-client relationship. It reports published tax rates and statutory attributes, with the sources this page cites. It cannot tell you which structure is better for you: that turns on your profit, the salary you could defend as reasonable compensation, every state you owe tax in, and plans for owners, investors and exit that no figure on this page measures. Confirm your own position with a CPA or tax attorney licensed in your state before you elect anything, because some elections are slow or costly to reverse.

Frequently Asked Questions

: Yes. A sole proprietorship is not a legal entity separate from its owner, so you convert by forming a new Illinois LLC and moving the business into it. File Articles of Organization (Form LLC-5.5) with the Illinois Secretary of State and pay the $150 filing fee. On the EIN, the IRS says a single-member LLC can keep using your sole proprietor EIN if it does not choose corporate or S-Corporation tax treatment, has no employees and owes no excise tax; otherwise it needs its own EIN, which you apply for on Form SS-4. Update your business licenses with the city or county where you operate, and check whether any state tax registrations must be reissued in the LLC's name. Forming the LLC gives you limited liability protection that a sole proprietorship lacks. Confirm current fees and submission requirements with the Secretary of State before filing.
: No, forming an Illinois LLC doesn't by itself reduce self-employment tax. By default, a single-member LLC is taxed like a sole proprietorship and a multi-member LLC like a partnership, and the owners generally owe 15.3% self-employment tax on net self-employment earnings. Self-employment tax is a federal tax paid to the IRS, not to a state agency: it is 12.4% for Social Security, which applies only up to an annual earnings cap, plus 2.9% for Medicare. However, an eligible LLC can file Form 2553 (Election by a Small Business Corporation) with the IRS to be taxed as an S-Corporation. You then pay yourself a reasonable salary, which is subject to Social Security and Medicare payroll taxes, and take remaining profits as distributions, which are not. The trade-off: an S-Corporation must run payroll, file payroll tax returns and a separate federal return (Form 1120-S), and pay for the accounting that requires. In Illinois, an LLC taxed as an S-Corporation also pays the 1.5% Personal Property Replacement Tax on its net Illinois income, so include it in the model. Whether the tax savings exceed those costs depends on your profits. Next step: consult an Illinois CPA to model the savings based on your projected income before filing Form 2553.
: Illinois charges $150 to file Articles of Organization (Form LLC-5.5) with the Illinois Secretary of State, or $400 if the LLC is organized with the ability to establish series. Expedited handling of the articles costs $100 more. An Illinois LLC then files a $75 annual report each year, due before the first day of its anniversary month, and a report not filed before the first day of the second month after the anniversary month triggers a $100 penalty. Illinois has no LLC franchise tax, but an LLC taxed as a partnership or S-Corporation pays the state's Personal Property Replacement Tax of 1.5% of its net Illinois income. Every Illinois LLC must name a registered agent: an individual Illinois resident or another person, such as a business entity, authorized to transact business in Illinois. If you use a paid service, Northwest Registered Agent charges $39 plus the state fee with a year of registered agent service included, then $125 a year, and ZenBusiness charges $0 plus the state fee, with registered agent service at $99 for the first year when you form with them, then $199 a year. File your Articles of Organization with the Illinois Secretary of State to get started.
: Yes. Under Illinois law, the debts, obligations and liabilities of an Illinois LLC, whether arising in contract, tort or otherwise, are solely the company's, and a member or manager is not personally liable for them solely by reason of being or acting as a member or manager. That protection has limits. It does not cover, for example, a debt you personally guarantee, and the same law says it does not limit liability imposed by other law, including the law of agency, contracts and torts, or court-imposed remedies such as piercing the LLC veil, so you remain liable for your own wrongful acts. Illinois law also says that an LLC's failure to observe the usual company formalities is not a ground for imposing personal liability on its members or managers, so skipping meetings or minutes is not, by itself, a ground for losing your protection. Keeping a separate business bank account and never mixing personal and business funds are still sensible practices, because courts can in some cases disregard an LLC and reach its owners ("piercing the veil"), and commingled funds invite that argument. If a creditor wins a judgment against your LLC for a company obligation you did not guarantee, it generally collects from the LLC's assets, not your personal home and savings. To secure this protection, file your Articles of Organization with the Illinois Secretary of State and open a dedicated business bank account from day one.
: Yes, Illinois allows single-member LLCs owned and controlled by one person, who can also manage the company. For federal tax purposes, the IRS treats a single-member LLC as a disregarded entity by default, so the LLC's income is reported on your personal return, just as with a sole proprietorship. An eligible LLC can instead elect S-Corporation tax treatment by filing Form 2553 with the IRS, which can reduce self-employment taxes on profits taken as distributions. The practical benefit: you gain personal liability protection for business debts while keeping tax filing simple. Illinois charges $150 to file Articles of Organization with the Illinois Secretary of State, and a $75 annual report each year. Next step: file your Articles of Organization with the Secretary of State, then open a business bank account to keep business and personal finances separate. The IRS says a single-member LLC with no employees, no excise tax and no corporate tax election can use your sole proprietor EIN instead of getting a new one.
: Yes, sole proprietorships don't require a formation filing in Illinois. You become a sole proprietor the moment you start conducting business, with no filing at the Secretary of State. There are still caveats. If you operate under a name other than your own legal name, check whether Illinois or your city or county requires you to register it as an assumed or trade name before you use it. Check with your city or county whether your type of business needs a local license, since local requirements and fees vary. Certain professions, such as real estate agents and health practitioners, require specific state licenses from their licensing boards. The practical implication: while you avoid the LLC filing fee and any LLC reports, you remain personally liable for all business debts and legal judgments, unlike an LLC owner. Your next step: contact your city or county to confirm licensing requirements and fees for your specific business type and location.

Sources

6 documents

Each entry below is a document recorded in our verified Illinois sources, and each entry says what the document is. Some statutory text is read from an accurate mirror rather than from the state's own host, and those say so. Where we hold the citation but no stable public link, the citation is printed on its own rather than pointed at a guessed address.

Illinois statute: 805 ILCS 180/50-10 (filing fees)
Illinois statute: 805 ILCS 180/10-10(a) (member liability shield)
Illinois statute: 805 ILCS 180/10-10, subsection (a-5) (liability under other law)
Illinois statute: 805 ILCS 180/10-10(c) (company formalities)
ilsos.gov/departments/business-services/limited-liability-companies.htmlIllinois Secretary of State: business entity filings
ilga.gov/legislation/ILCS/details?ActName=Limited+Liability+Company+Act.&ActID=2290&ChapterID=65&ChapAct=805+ILCS+180%2F&SeqStart=14450000&SeqEnd=15800000Illinois LLC filing fees

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Edmond Hui · Founder, MyStateLLC

Edmond Hui is a software engineer and serial entrepreneur based in New York who has founded multiple online businesses across e-commerce, media, and information publishing. Before transitioning into tech, he spent years as a commercial real estate professional closing deals totaling over 100,000 square feet, giving him firsthand experience with business formation and entity structuring. He built MyStateLLC to provide the free, state-specific LLC guidance he wished existed when forming his own companies.

How we check facts

LLC vs Sole Proprietorship: Side-by-Side

When an LLC Makes More Sense

When a Sole Proprietorship Makes More Sense

Tax Deep Dive

Sole Proprietorship Tax

LLC Default Tax

LLC S-Corp Election

Frequently Asked Questions

Sources

More for Illinois LLCs

Start and set up

Taxes, money and growth

Stay compliant

Operate in other states

Compare structures

By owner type

By profession

Ready to Form Your Illinois LLC?

More Illinois LLC Guides

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