LLC vs. S-Corp vs. C-Corp in Illinois: Choosing the Right Business Entity
The choice of entity determines how your business is taxed, how you are protected from personal liability, how ownership can be transferred, and how the business can be financed and eventually sold. In Illinois, the main choices are the limited liability company (LLC), the S-corporation (S-corp), and the C-corporation (C-corp). Each has real advantages and real limitations — the right choice depends on the specific facts of your situation.
The Limited Liability Company (LLC)
The Illinois LLC (805 ILCS 180) is the most popular entity form for small and mid-size businesses, for good reason. It provides limited liability protection for members, is highly flexible in management structure and profit allocation, and avoids corporate formality requirements. By default, a single-member LLC is taxed as a disregarded entity (income on Schedule C) and a multi-member LLC as a partnership (income on Schedule K-1). In both cases, income is taxed once — at the individual level.
The main limitation for active business owners is self-employment tax. An LLC owner pays self-employment tax (15.3% on the first $184,500 in 2026, 2.9% above that) on all net business income. For an LLC earning $200,000 in net profit, the self-employment tax liability is approximately $28,200 — a cost the S-corporation structure can reduce.
The S-Corporation
An S-corporation passes income through to shareholders without entity-level federal income tax. The key difference from an LLC is how compensation to active owner-employees is handled. An S-corp owner who works in the business must pay themselves a “reasonable salary,” which is subject to payroll taxes. Only the remaining profit distributed above the salary avoids self-employment and payroll taxes.
Example: S-corp generates $200,000 net income. Owner pays themselves $80,000 salary — subject to payroll taxes (~$12,200 combined). Remaining $120,000 distributed as shareholder distribution: no self-employment or payroll taxes. Net payroll tax saving versus an LLC: roughly $16,000 per year — often enough to justify the additional administrative cost of running an S-corp.
S-corp limitations: no more than 100 shareholders, all must be US citizens or resident aliens, only one class of stock, corporations and most trusts cannot be shareholders. In Illinois, S-corporations are also subject to the Illinois Personal Property Replacement Tax (1.5% of net income), which partially offsets the federal payroll tax savings.
The C-Corporation
A C-corporation is taxed as a separate entity at 21% federal corporate income tax, plus Illinois corporate income tax of 9.5%. Unlike an LLC or S-corp, a C-corp’s income is potentially taxed twice: at the corporate level and again when profits are distributed to shareholders as dividends. This double taxation makes the C-corp generally unattractive for small closely held businesses that distribute most profits to owners.
The C-corp becomes more attractive when: the business is retaining and reinvesting earnings at a 21% rate (rather than passing through at individual rates up to 37%); the business is seeking venture capital or institutional investment; the founders plan to take the company public or sell to a strategic buyer; or the Qualified Small Business Stock (QSBS) exclusion under IRC Section 1202 is relevant (up to $10 million of gain from C-corp stock excluded from federal capital gains tax if held more than five years).
Choosing the Right Structure: Quick Reference
| Factor | LLC (default) | S-Corp | C-Corp |
|---|---|---|---|
| Liability protection | Yes | Yes | Yes |
| Double taxation risk | No | No | Yes (if dividends paid) |
| Self-employment tax savings | No | Yes (via salary split) | Yes (via salary split) |
| Ownership flexibility | High | Limited | High |
| Institutional investment | Often yes | No | Yes |
| Administrative complexity | Low | Medium | High |
The Right Choice Requires Both Legal and Tax Analysis
Entity selection is one of the few decisions in business planning requiring simultaneous legal and tax analysis. The legal structure determines liability exposure, governance rights, and transfer restrictions. The tax structure determines annual tax cost, treatment of compensation, and tax consequences of an eventual sale. Making the legal choice without the tax analysis — or the tax analysis without the legal drafting — produces an incomplete picture. This is the practical advantage of working with an advisor who holds both credentials.